Cisco Systems Ios Xr Users Manual
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2015-01-05
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Cisco IOS XR Routing Configuration Guide Cisco IOS XR Software Release 3.2 Corporate Headquarters Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134-1706 USA http://www.cisco.com Tel: 408 526-4000 800 553-NETS (6387) Fax: 408 526-4100 Text Part Number: OL-5554-05 THE SPECIFICATIONS AND INFORMATION REGARDING THE PRODUCTS IN THIS MANUAL ARE SUBJECT TO CHANGE WITHOUT NOTICE. ALL STATEMENTS, INFORMATION, AND RECOMMENDATIONS IN THIS MANUAL ARE BELIEVED TO BE ACCURATE BUT ARE PRESENTED WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED. USERS MUST TAKE FULL RESPONSIBILITY FOR THEIR APPLICATION OF ANY PRODUCTS. THE SOFTWARE LICENSE AND LIMITED WARRANTY FOR THE ACCOMPANYING PRODUCT ARE SET FORTH IN THE INFORMATION PACKET THAT SHIPPED WITH THE PRODUCT AND ARE INCORPORATED HEREIN BY THIS REFERENCE. IF YOU ARE UNABLE TO LOCATE THE SOFTWARE LICENSE OR LIMITED WARRANTY, CONTACT YOUR CISCO REPRESENTATIVE FOR A COPY. The Cisco implementation of TCP header compression is an adaptation of a program developed by the University of California, Berkeley (UCB) as part of UCB’s public domain version of the UNIX operating system. All rights reserved. Copyright © 1981, Regents of the University of California. NOTWITHSTANDING ANY OTHER WARRANTY HEREIN, ALL DOCUMENT FILES AND SOFTWARE OF THESE SUPPLIERS ARE PROVIDED “AS IS” WITH ALL FAULTS. CISCO AND THE ABOVE-NAMED SUPPLIERS DISCLAIM ALL WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING, WITHOUT LIMITATION, THOSE OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OR ARISING FROM A COURSE OF DEALING, USAGE, OR TRADE PRACTICE. IN NO EVENT SHALL CISCO OR ITS SUPPLIERS BE LIABLE FOR ANY INDIRECT, SPECIAL, CONSEQUENTIAL, OR INCIDENTAL DAMAGES, INCLUDING, WITHOUT LIMITATION, LOST PROFITS OR LOSS OR DAMAGE TO DATA ARISING OUT OF THE USE OR INABILITY TO USE THIS MANUAL, EVEN IF CISCO OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. q g g g y g g y y iQuick Study are service marks of Cisco Systems, Inc.; and Access Registrar, Aironet, ASIST, BPX, Catalyst, CCDA, CCDP, CCIE, CCIP, CCNA, CCNP, Cisco, the Cisco Certified Internetwork Expert logo, Cisco IOS, Cisco Press, Cisco Systems, Cisco Systems Capital, the Cisco Systems logo, Cisco Unity, Empowering the Internet Generation, Enterprise/Solver, EtherChannel, EtherFast, EtherSwitch, Fast Step, FormShare, GigaDrive, GigaStack, HomeLink, Internet Quotient, IOS, IP/TV, iQ Expertise, the iQ logo, iQ Net Readiness Scorecard, LightStream, Linksys, MeetingPlace, MGX, the Networkers logo, Networking Academy, Network Registrar, Packet, PIX, Post-Routing, Pre-Routing, ProConnect, RateMUX, ScriptShare, SlideCast, SMARTnet, StrataView Plus, TeleRouter, The Fastest Way to Increase Your Internet Quotient, and TransPath are registered trademarks of Cisco Systems, Inc. and/or its affiliates in the United States and certain other countries. All other trademarks mentioned in this document or Website are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (0502R) Cisco IOS XR Routing Configuration Guide Copyright © 2005 Cisco Systems, Inc. All rights reserved. C O N T E N T S Preface xi Document Revision History xi Obtaining Documentation xii Cisco.com xii Product Documentation DVD xii Ordering Documentation xii Documentation Feedback xiii Cisco Product Security Overview xiii Reporting Security Problems in Cisco Products xiii Obtaining Technical Assistance xiv Cisco Technical Support & Documentation Website Submitting a Service Request xv Definitions of Service Request Severity xv Obtaining Additional Publications and Information Implementing BGP on Cisco IOS XR Software Contents xiv xv RC-1 RC-1 Prerequisites for Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software BGP Functional Overview RC-2 BGP Router Identifier RC-3 BGP Default Limits RC-3 BGP Validation of Local Next-Hop Addresses RC-4 BGP Configuration RC-4 No Default Address Family RC-15 Routing Policy Enforcement RC-16 Table Policy RC-18 Update Groups RC-18 BGP Best Path Algorithm RC-18 Multiprotocol BGP RC-21 Route Dampening RC-23 BGP Routing Domain Confederation RC-24 BGP Route Reflectors RC-24 Default Address Family for show Commands RC-27 RC-2 RC-2 Cisco IOS XR Routing Configuration Guide RC-iii Contents How to Implement BGP on Cisco IOS XR Software RC-27 Enabling BGP Routing RC-28 Configuring a Routing Domain Confederation for BGP RC-31 Resetting eBGP Session Immediately Upon Link Failure RC-33 Logging Neighbor Changes RC-34 Adjusting BGP Timers RC-34 Changing the BGP Default Local Preference Value RC-35 Configuring the MED Metric for BGP RC-36 Configuring BGP Weights RC-38 Tuning the BGP Best Path Calculation RC-39 Indicating BGP Backdoor Routes RC-41 Configuring Aggregate Addresses RC-43 Redistributing iBGP Routes into IGP RC-44 Redistributing Prefixes into Multiprotocol BGP RC-46 Configuring BGP Route Dampening RC-48 Applying Policy When Updating the Routing Table RC-52 Setting BGP Administrative Distance RC-53 Configuring a BGP Neighbor Group RC-55 Configuring a BGP Neighbor RC-58 Configuring a Route Reflector for BGP RC-60 Configuring BGP Route Filtering by Route Policy RC-62 Disabling Next Hop Processing on BGP Updates RC-64 Configuring BGP Community and Extended-Community Filtering RC-65 Configuring Software to Store Updates from a Neighbor RC-67 Disabling a BGP Neighbor RC-69 Resetting Neighbors Using BGP Dynamic Inbound Soft Reset RC-71 Resetting Neighbors Using BGP Outbound Soft Reset RC-71 Resetting Neighbors Using BGP Hard Reset RC-72 Clearing Caches, Tables and Databases RC-73 Displaying System and Network Statistics RC-73 Monitoring BGP Update Groups RC-75 Configuration Examples for Implementing BGP on Cisco IOS XR Software Enabling BGP: Example RC-76 Displaying BGP Update Groups: Example RC-77 BGP Neighbor Configuration: Example RC-78 BGP Confederation: Example RC-78 BGP Route Reflector: Example RC-79 Where to Go Next RC-79 Additional References Cisco IOS XR Routing Configuration Guide RC-iv RC-80 RC-76 Contents Related Documents RC-80 Standards RC-80 MIBs RC-80 RFCs RC-80 Technical Assistance RC-81 Implementing IS-IS on Cisco IOS XR Software Contents RC-83 RC-83 Prerequisites for Implementing IS-IS on Cisco IOS XR Software Restrictions for Implementing IS-IS on Cisco IOS XR Software RC-84 RC-84 Information About Implementing IS-IS on Cisco IOS XR Software RC-84 IS-IS Functional Overview RC-85 Key Features Supported in the Cisco IOS XR IS-IS Implementation RC-85 IS-IS Configuration Grouping RC-85 IS-IS Interfaces RC-86 Multitopology Configuration RC-86 IPv6 Routing and Configuring IPv6 Addressing RC-86 Limit LSP Flooding RC-86 Maximum LSP Lifetime and Refresh Interval RC-87 Overload Bit Configuration During Multitopology Operation RC-87 Single-Topology IPv6 Support RC-87 Multitopology IPv6 Support RC-88 Nonstop Forwarding RC-88 Multi-Instance IS-IS RC-89 Multiprotocol Label Switching Traffic Engineering RC-89 Overload Bit on Router RC-89 Default Routes RC-90 Attached Bit on an IS-IS Instance RC-90 Multicast-Intact Feature RC-90 How to Implement IS-IS on Cisco IOS XR Software RC-91 Enabling IS-IS and Configuring Level 1 or Level 2 Routing RC-91 Configuring Single Topology for IS-IS RC-93 Configuring Multitopology for IS-IS RC-98 Controlling LSP Flooding for IS-IS RC-102 Configuring Nonstop Forwarding for IS-IS RC-106 Configuring Authentication for IS-IS RC-108 Configuring MPLS Traffic Engineering for IS-IS RC-110 Tuning Adjacencies for IS-IS on Point-to-Point Interfaces RC-113 Setting SPF Interval for a Single-Topology IPv4 and IPv6 Configuration Enabling Multicast-Intact for IS-IS RC-118 RC-116 Cisco IOS XR Routing Configuration Guide RC-v Contents Customizing Routes for IS-IS RC-119 Configuration Examples for Implementing IS-IS on Cisco IOS XR Software RC-122 Configuring Single-Topology IS-IS for IPv6: Example RC-122 Configuring Multitopology IS-IS for IPv6: Example RC-123 Redistributing IS-IS Routes Between Multiple Instances: Example RC-123 Where to Go Next RC-124 Additional References RC-124 Related Documents RC-124 Standards RC-124 MIBs RC-124 RFCs RC-125 Technical Assistance RC-125 Implementing OSPF on Cisco IOS XR Software Contents RC-127 RC-127 Prerequisites for Implementing OSPF on Cisco IOS XR Software RC-128 Information About Implementing OSPF on Cisco IOS XR Software RC-128 OSPF Functional Overview RC-129 Key Features Supported in the Cisco IOS XR OSPF Implementation RC-130 Comparison of Cisco IOS XR OSPFv3 and OSPFv2 RC-131 Importing Addresses into OSPFv3 RC-131 OSPF Hierarchical CLI and CLI Inheritance RC-131 OSPF Routing Components RC-132 OSPF Process and Router ID RC-134 Supported OSPF Network Types RC-135 Route Authentication Methods for OSPF Version 2 RC-135 Neighbors and Adjacency for OSPF RC-136 Designated Router (DR) for OSPF RC-136 Default Route for OSPF RC-137 Link-State Advertisement Types for OSPF Version 2 RC-137 Link-State Advertisement Types for OSPFv3 RC-137 Virtual Link and Transit Area for OSPF RC-138 Route Redistribution for OSPF RC-139 OSPF Shortest Path First Throttling RC-139 Nonstop Forwarding for OSPF Version 2 RC-140 Load Balancing in OSPF Version 2 and OSPFv3 RC-141 Graceful Restart for OSPFv3 RC-141 Multicast-Intact Feature RC-144 How to Implement OSPF on Cisco IOS XR Software Cisco IOS XR Routing Configuration Guide RC-vi RC-144 Contents Enabling OSPF RC-145 Configuring Stub and Not-so-Stubby Area Types RC-147 Configuring Neighbors for Nonbroadcast Networks RC-150 Configuring Authentication at Different Hierarchical Levels for OSPF Version 2 RC-155 Controlling the Frequency that the Same LSA Is Originated or Accepted for OSPF RC-158 Creating a Virtual Link with MD5 Authentication to Area 0 for OSPF RC-160 Summarizing Subnetwork LSAs on an OSPF ABR RC-164 Redistributing Routes from One IGP into OSPF RC-166 Configuring OSPF Shortest Path First Throttling RC-170 Configuring Nonstop Forwarding for OSPF Version 2 RC-173 Configuring OSPF Version 2 for MPLS Traffic Engineering RC-175 Verifying OSPF Configuration and Operation RC-180 Configuring OSPFv3 Graceful Restart RC-181 Enabling Multicast-Intact for OSPFv2 RC-186 Configuration Examples for Implementing OSPF on Cisco IOS XR Software RC-187 Cisco IOS XR for OSPF Version 2 Configuration: Example RC-188 CLI Inheritance and Precedence for OSPF Version 2: Example RC-189 MPLS TE for OSPF Version 2: Example RC-190 ABR with Summarization for OSPFv3: Example RC-190 ABR Stub Area for OSPFv3: Example RC-190 ABR Totally Stub Area for OSPFv3: Example RC-191 Route Redistribution for OSPFv3: Example RC-191 Virtual Link Configured Through Area 1 for OSPFv3: Example RC-191 Virtual Link Configured with MD5 Authentication for OSPF Version 2: Example RC-192 Where to Go Next RC-192 Additional References RC-193 Related Documents RC-193 Standards RC-193 MIBs RC-193 RFCs RC-193 Technical Assistance RC-194 Implementing and Monitoring RIB on Cisco IOS XR Software Contents RC-195 RC-195 Prerequisites for Implementing RIB on Cisco IOS XR Software Information About RIB Configuration RC-196 Overview of RIB RC-196 RIB Data Structures in BGP and Other Protocols RIB Administrative Distance RC-197 RC-196 RC-196 Cisco IOS XR Routing Configuration Guide RC-vii Contents RIB Support for IPv4 and IPv6 RC-197 How to Deploy and Monitor RIB RC-198 Verifying RIB Configuration Using the Routing Table RC-198 Verifying Networking and Routing Problems RC-198 Configuration Examples for RIB Monitoring RC-200 Output of show route Command: Example RC-200 Output of show route backup Command: Example RC-201 Output of show route best-local Command: Example RC-201 Output of show route connected Command: Example RC-201 Output of show route local Command: Example RC-201 Output of show route longer-prefixes Command: Example RC-202 Output of show route next-hop Command: Example RC-202 Where to Go Next RC-202 Additional References RC-203 Related Documents RC-203 Standards RC-203 MIBs RC-203 RFCs RC-204 Technical Assistance RC-204 Implementing Routing Policy on Cisco IOS XR Software Contents RC-205 RC-205 Prerequisites for Implementing Routing Policy RC-206 Information About Implementing Routing Policy RC-206 Routing Policy Language RC-206 Routing Policy Configuration Basics RC-213 Policy Definitions RC-213 Parameterization RC-214 Semantics of Policy Application RC-215 Policy Statements RC-219 Attach Points RC-223 Attached Policy Modification RC-235 Nonattached Policy Modification RC-235 How to Implement Routing Policy RC-237 Defining a Route Policy RC-237 Attaching a Routing Policy to a BGP Neighbor RC-238 Modifying a Routing Policy Using the Microemacs Editor Configuration Examples for Implementing Routing Policy Routing Policy Definition: Example RC-241 Cisco IOS XR Routing Configuration Guide RC-viii RC-240 RC-241 Contents Simple Inbound Policy: Example RC-242 Modular Inbound Policy: Example RC-243 Translating Cisco IOS Route Maps to Cisco IOS XR Routing Policy Language: Example RC-244 Additional References RC-244 Related Documents RC-244 Standards RC-244 MIBs RC-245 RFCs RC-245 Technical Assistance RC-245 Implementing Static Routes on Cisco IOS XR Software Contents RC-247 RC-247 Prerequisites for Implementing Static Routes on Cisco IOS XR Software Information About Implementing Static Routes on Cisco IOS XR Software Static Route Functional Overview RC-248 Default Administrative Distance RC-248 Directly Connected Routes RC-249 Recursive Static Routes RC-249 Fully Specified Static Routes RC-250 Floating Static Routes RC-250 RC-248 RC-248 How to Implement Static Routes on Cisco IOS XR Software RC-250 Configuring a Static Route RC-250 Configuring a Floating Static Route RC-251 Changing the Maximum Number of Allowable Static Routes RC-253 Configuration Examples RC-255 Configuring Traffic Discard: Example RC-255 Configuring a Fixed Default Route: Example RC-255 Configuring a Floating Static Route: Example RC-255 Where to Go Next RC-255 Additional References RC-256 Related Documents RC-256 Standards RC-256 MIBs RC-256 RFCs RC-256 Technical Assistance RC-256 Cisco IOS XR Routing Configuration Guide RC-ix Contents Cisco IOS XR Routing Configuration Guide RC-x Preface This is the preface for the Cisco IOS XR Routing Configuration Guide. The preface contains the following sections: • Document Revision History, page xi • Obtaining Documentation, page xii • Documentation Feedback, page xiii • Cisco Product Security Overview, page xiii • Obtaining Technical Assistance, page xiv • Obtaining Additional Publications and Information, page xv Document Revision History The Document Revision History table records technical changes to this document. Table 1 shows the document revision number for the change, the date of the change, and a brief summary of the change. Note that not all Cisco documents use a Document Revision History table. Table 1 Document Revision History Revision Date Change Summary OL-5554-05 November 2005 Added description for the OSPFv3 Graceful Restart feature. August 31, 2005 Implementing IS-IS on Cisco IOS XR Software changes: October 31, 2004 Implementing IS-IS on Cisco IOS XR Software changes: OL-5554-04 OL-5554-02 OL-5554-01 Added descriptions for the multicast-intact option in IS-IS and OSPFv2. Updated the IS-IS module to include the ability to configure a broadcast medium connecting two networking devices as a point-to-point link. Changes to lsp-gen-interval, spf-interval, and show isis spf-log information. July 30, 2004 Initial release of this document. Cisco IOS XR Routing Configuration Guide xi Preface Obtaining Documentation Obtaining Documentation Cisco documentation and additional literature are available on Cisco.com. Cisco also provides several ways to obtain technical assistance and other technical resources. These sections explain how to obtain technical information from Cisco Systems. Cisco.com You can access the most current Cisco documentation at this URL: http://www.cisco.com/techsupport You can access the Cisco website at this URL: http://www.cisco.com You can access international Cisco websites at this URL: http://www.cisco.com/public/countries_languages.shtml Product Documentation DVD Cisco documentation and additional literature are available in the Product Documentation DVD package, which may have shipped with your product. The Product Documentation DVD is updated regularly and may be more current than printed documentation. The Product Documentation DVD is a comprehensive library of technical product documentation on portable media. The DVD enables you to access multiple versions of hardware and software installation, configuration, and command guides for Cisco products and to view technical documentation in HTML. With the DVD, you have access to the same documentation that is found on the Cisco website without being connected to the Internet. Certain products also have .pdf versions of the documentation available. The Product Documentation DVD is available as a single unit or as a subscription. Registered Cisco.com users (Cisco direct customers) can order a Product Documentation DVD (product number DOC-DOCDVD=) from Cisco Marketplace at this URL: http://www.cisco.com/go/marketplace/ Ordering Documentation Beginning June 30, 2005, registered Cisco.com users may order Cisco documentation at the Product Documentation Store in the Cisco Marketplace at this URL: http://www.cisco.com/go/marketplace/ Nonregistered Cisco.com users can order technical documentation from 8:00 a.m. to 5:00 p.m. (0800 to 1700) PDT by calling 1 866 463-3487 in the United States and Canada, or elsewhere by calling 011 408 519-5055. You can also order documentation by e-mail at tech-doc-store-mkpl@external.cisco.com or by fax at 1 408 519-5001 in the United States and Canada, or elsewhere at 011 408 519-5001. Cisco IOS XR Routing Configuration Guide xii Preface Documentation Feedback Documentation Feedback You can rate and provide feedback about Cisco technical documents by completing the online feedback form that appears with the technical documents on Cisco.com. You can send comments about Cisco documentation to bug-doc@cisco.com. You can submit comments by using the response card (if present) behind the front cover of your document or by writing to the following address: Cisco Systems Attn: Customer Document Ordering 170 West Tasman Drive San Jose, CA 95134-9883 We appreciate your comments. Cisco Product Security Overview Cisco provides a free online Security Vulnerability Policy portal at this URL: http://www.cisco.com/en/US/products/products_security_vulnerability_policy.html From this site, you can perform these tasks: • Report security vulnerabilities in Cisco products. • Obtain assistance with security incidents that involve Cisco products. • Register to receive security information from Cisco. A current list of security advisories and notices for Cisco products is available at this URL: http://www.cisco.com/go/psirt If you prefer to see advisories and notices as they are updated in real time, you can access a Product Security Incident Response Team Really Simple Syndication (PSIRT RSS) feed from this URL: http://www.cisco.com/en/US/products/products_psirt_rss_feed.html Reporting Security Problems in Cisco Products Cisco is committed to delivering secure products. We test our products internally before we release them, and we strive to correct all vulnerabilities quickly. If you think that you might have identified a vulnerability in a Cisco product, contact PSIRT: • Emergencies — security-alert@cisco.com An emergency is either a condition in which a system is under active attack or a condition for which a severe and urgent security vulnerability should be reported. All other conditions are considered nonemergencies. • Nonemergencies — psirt@cisco.com In an emergency, you can also reach PSIRT by telephone: • 1 877 228-7302 • 1 408 525-6532 Cisco IOS XR Routing Configuration Guide xiii Preface Obtaining Technical Assistance Tip We encourage you to use Pretty Good Privacy (PGP) or a compatible product to encrypt any sensitive information that you send to Cisco. PSIRT can work from encrypted information that is compatible with PGP versions 2.x through 8.x. Never use a revoked or an expired encryption key. The correct public key to use in your correspondence with PSIRT is the one linked in the Contact Summary section of the Security Vulnerability Policy page at this URL: http://www.cisco.com/en/US/products/products_security_vulnerability_policy.html The link on this page has the current PGP key ID in use. Obtaining Technical Assistance Cisco Technical Support provides 24-hour-a-day award-winning technical assistance. The Cisco Technical Support & Documentation website on Cisco.com features extensive online support resources. In addition, if you have a valid Cisco service contract, Cisco Technical Assistance Center (TAC) engineers provide telephone support. If you do not have a valid Cisco service contract, contact your reseller. Cisco Technical Support & Documentation Website The Cisco Technical Support & Documentation website provides online documents and tools for troubleshooting and resolving technical issues with Cisco products and technologies. The website is available 24 hours a day, at this URL: http://www.cisco.com/techsupport Access to all tools on the Cisco Technical Support & Documentation website requires a Cisco.com user ID and password. If you have a valid service contract but do not have a user ID or password, you can register at this URL: http://tools.cisco.com/RPF/register/register.do Note Use the Cisco Product Identification (CPI) tool to locate your product serial number before submitting a web or phone request for service. You can access the CPI tool from the Cisco Technical Support & Documentation website by clicking the Tools & Resources link under Documentation & Tools. Choose Cisco Product Identification Tool from the Alphabetical Index drop-down list, or click the Cisco Product Identification Tool link under Alerts & RMAs. The CPI tool offers three search options: by product ID or model name; by tree view; or for certain products, by copying and pasting show command output. Search results show an illustration of your product with the serial number label location highlighted. Locate the serial number label on your product and record the information before placing a service call. Cisco IOS XR Routing Configuration Guide xiv Preface Obtaining Additional Publications and Information Submitting a Service Request Using the online TAC Service Request Tool is the fastest way to open S3 and S4 service requests. (S3 and S4 service requests are those in which your network is minimally impaired or for which you require product information.) After you describe your situation, the TAC Service Request Tool provides recommended solutions. If your issue is not resolved using the recommended resources, your service request is assigned to a Cisco engineer. The TAC Service Request Tool is located at this URL: http://www.cisco.com/techsupport/servicerequest For S1 or S2 service requests or if you do not have Internet access, contact the Cisco TAC by telephone. (S1 or S2 service requests are those in which your production network is down or severely degraded.) Cisco engineers are assigned immediately to S1 and S2 service requests to help keep your business operations running smoothly. To open a service request by telephone, use one of the following numbers: Asia-Pacific: +61 2 8446 7411 (Australia: 1 800 805 227) EMEA: +32 2 704 55 55 USA: 1 800 553-2447 For a complete list of Cisco TAC contacts, go to this URL: http://www.cisco.com/techsupport/contacts Definitions of Service Request Severity To ensure that all service requests are reported in a standard format, Cisco has established severity definitions. Severity 1 (S1)—Your network is “down,” or there is a critical impact to your business operations. You and Cisco will commit all necessary resources around the clock to resolve the situation. Severity 2 (S2)—Operation of an existing network is severely degraded, or significant aspects of your business operation are negatively affected by inadequate performance of Cisco products. You and Cisco will commit full-time resources during normal business hours to resolve the situation. Severity 3 (S3)—Operational performance of your network is impaired, but most business operations remain functional. You and Cisco will commit resources during normal business hours to restore service to satisfactory levels. Severity 4 (S4)—You require information or assistance with Cisco product capabilities, installation, or configuration. There is little or no effect on your business operations. Obtaining Additional Publications and Information Information about Cisco products, technologies, and network solutions is available from various online and printed sources. • Cisco Marketplace provides a variety of Cisco books, reference guides, documentation, and logo merchandise. Visit Cisco Marketplace, the company store, at this URL: http://www.cisco.com/go/marketplace/ Cisco IOS XR Routing Configuration Guide xv Preface Obtaining Additional Publications and Information • Cisco Press publishes a wide range of general networking, training and certification titles. Both new and experienced users will benefit from these publications. For current Cisco Press titles and other information, go to Cisco Press at this URL: http://www.ciscopress.com • Packet magazine is the Cisco Systems technical user magazine for maximizing Internet and networking investments. Each quarter, Packet delivers coverage of the latest industry trends, technology breakthroughs, and Cisco products and solutions, as well as network deployment and troubleshooting tips, configuration examples, customer case studies, certification and training information, and links to scores of in-depth online resources. You can access Packet magazine at this URL: http://www.cisco.com/packet • iQ Magazine is the quarterly publication from Cisco Systems designed to help growing companies learn how they can use technology to increase revenue, streamline their business, and expand services. The publication identifies the challenges facing these companies and the technologies to help solve them, using real-world case studies and business strategies to help readers make sound technology investment decisions. You can access iQ Magazine at this URL: http://www.cisco.com/go/iqmagazine or view the digital edition at this URL: http://ciscoiq.texterity.com/ciscoiq/sample/ • Internet Protocol Journal is a quarterly journal published by Cisco Systems for engineering professionals involved in designing, developing, and operating public and private internets and intranets. You can access the Internet Protocol Journal at this URL: http://www.cisco.com/ipj • Networking products offered by Cisco Systems, as well as customer support services, can be obtained at this URL: http://www.cisco.com/en/US/products/index.html • Networking Professionals Connection is an interactive website for networking professionals to share questions, suggestions, and information about networking products and technologies with Cisco experts and other networking professionals. Join a discussion at this URL: http://www.cisco.com/discuss/networking • World-class networking training is available from Cisco. You can view current offerings at this URL: http://www.cisco.com/en/US/learning/index.html Cisco IOS XR Routing Configuration Guide xvi Implementing BGP on Cisco IOS XR Software The Border Gateway Protocol (BGP) is an Exterior Gateway Protocol (EGP) that allows you to create loop-free interdomain routing between autonomous systems. An autonomous system is a set of routers under a single technical administration. Routers in an autonomous system can use multiple Interior Gateway Protocols (IGP) to exchange routing information inside the autonomous system and an EGP to route packets outside the autonomous system. This module describes information that is unique to BGP for IP Version 4 (IPv4) and IP Version 6 (IPv6) implementation in Cisco IOS XR Software. Note For more information about BGP on the Cisco IOS XR software and complete descriptions of the BGP commands listed in this module, you can see the “Related Documents” section of this module. To locate documentation for other commands that might appear while executing a configuration task, search online in the Cisco IOS XR software master command index. Feature History for Implementing BGP on Cisco IOS XR Configuration Module Release Modification Release 2.0 This feature was introduced on the Cisco CRS-1. Release 3.0 No modification. Release 3.2 Support was added for the Cisco XR 12000 Series Router. Contents • Prerequisites for Implementing BGP on Cisco IOS XR Software, page RC-2 • Information About Implementing BGP on Cisco IOS XR Software, page RC-2 • How to Implement BGP on Cisco IOS XR Software, page RC-27 • Configuration Examples for Implementing BGP on Cisco IOS XR Software, page RC-76 • Where to Go Next, page RC-79 • Additional References, page RC-80 Cisco IOS XR Routing Configuration Guide RC-1 Implementing BGP on Cisco IOS XR Software Prerequisites for Implementing BGP on Cisco IOS XR Software Prerequisites for Implementing BGP on Cisco IOS XR Software To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide. Information About Implementing BGP on Cisco IOS XR Software To implement BGP, you need to understand the following concepts: • BGP Functional Overview, page RC-2 • BGP Router Identifier, page RC-3 • BGP Default Limits, page RC-3 • BGP Validation of Local Next-Hop Addresses, page RC-4 • BGP Configuration, page RC-4 • No Default Address Family, page RC-15 • Routing Policy Enforcement, page RC-16 • Update Groups, page RC-18 • BGP Best Path Algorithm, page RC-18 • Multiprotocol BGP, page RC-21 • Route Dampening, page RC-23 • BGP Routing Domain Confederation, page RC-24 • BGP Route Reflectors, page RC-24 • Default Address Family for show Commands, page RC-27 BGP Functional Overview BGP uses TCP as its transport protocol. Two BGP routers form a TCP connection between one another (peer routers) and exchange messages to open and confirm the connection parameters. BGP routers exchange network reachability information. This information is mainly an indication of the full paths (BGP autonomous system numbers) that a route should take to reach the destination network. This information helps construct a graph that shows which autonomous systems are loop free and where routing policies can be applied to enforce restrictions on routing behavior. Any two routers forming a TCP connection to exchange BGP routing information are called peers or neighbors. BGP peers initially exchange their full BGP routing tables. After this exchange, incremental updates are sent as the routing table changes. BGP keeps a version number of the BGP table, which is the same for all of its BGP peers. The version number changes whenever BGP updates the table due to routing information changes. Keepalive packets are sent to ensure that the connection is alive between the BGP peers and notification packets are sent in response to error or special conditions. Cisco IOS XR Routing Configuration Guide RC-2 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software BGP Router Identifier For BGP sessions between neighbors to be established, BGP must be assigned a router ID. The router ID is sent to BGP peers in the OPEN message when a BGP session is established. BGP attempts to obtain a router ID in the following ways (in order of preference): Note • By means of the address configured using the bgp router-id command in router configuration mode. • By assigning a primary IPv4 address to the interface specified using the bgp router-id command in router configuration mode. If the specified interface does not have an IPv4 address, or is not up, BGP will fail to obtain a router ID. • By using the address specified with the router-id command in global configuration mode if the router is booted with the saved router-id command and if the ID from this command is available when the last saved loopback configuration is applied. • By using the primary IPv4 address on the interface specified with the router-id command in global configuration mode if the box is booted with the saved router-id command in global configuration mode and if the router ID is up by the time all saved loopback configurations are applied. • By using the highest IPv4 address on a loopback interface in the system if the router is booted with saved loopback address configuration. • By using the primary IPv4 address of the first loopback address that gets configured if there are not any in the saved configuration. If none of these methods for obtaining a router ID succeeds, BGP does not have a router ID and cannot establish any peering sessions with BGP neighbors. In such an instance, an error message is entered in the system log, and the show bgp summary command displays a router ID of 0.0.0.0. After BGP has obtained a router ID, it continues to use it even if a better router ID becomes available. This usage avoids unnecessary flapping for all BGP sessions. However, if the router ID currently in use becomes invalid (because the interface goes down or its configuration is changed), BGP selects a new router ID (using the rules described) and all established peering sessions are reset. We strongly recommend that the bgp router-id command is configured to prevent unnecessary changes to the router ID (and consequent flapping of BGP sessions). BGP Default Limits Cisco IOS XR BGP imposes maximum limits on the number of neighbors that can be configured on the router and on the maximum number of prefixes that are accepted from a peer for a given address family. This limitation safeguards the router from resource depletion caused by misconfiguration, either locally or on the remote neighbor. The following limits apply to BGP configurations: • The default maximum number of peers that can be configured is 1024. The default can be changed using the bgp maximum neighbor command. The limit range is 1 to 1500. Any attempt to configure additional peers beyond the maximum limit or set the maximum limit to a number that is less than the number of peers currently configured will fail. • To prevent a peer from flooding BGP with advertisements, a limit is placed on the number of prefixes that are accepted from a peer for each supported address family. The default limits can be overridden through configuration of the maximum-prefix limit command for the peer for the appropriate address family. The following default limits are used if the user does not configure the maximum number of prefixes for the address family: Cisco IOS XR Routing Configuration Guide RC-3 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software – 512K (524,288) prefixes for IPv4 unicast. – 128K (131,072) prefixes for IPv4 multicast. – 128K (131,072) prefixes for IPv6 unicast. A cease notification message is sent to the neighbor and the peering with the neighbor is terminated when the number of prefixes received from the peer for a given address family exceeds the maximum limit (either set by default or configured by the user) for that address family. It is possible that the maximum number of prefixes for a neighbor for a given address family has been configured after the peering with the neighbor has been established and a certain number of prefixes have already been received from the neighbor for that address family. A cease notification message is sent to the neighbor and peering with the neighbor is terminated immediately after the configuration if the configured maximum number of prefixes is fewer than the number of prefixes that have already been received from the neighbor for the address family. BGP Validation of Local Next-Hop Addresses When Cisco IOS XR BGP receives a route advertisement from a neighbor, it validates the next-hop address contained in the route by verifying that the next-hop address is not the same as an IP address assigned to an interface on this router (for example, a local address). If the received next-hop address is a local address, the update is dropped. However, if the next-hop address is set to a local address by the configured inbound policy, the update is not dropped, is treated as a valid next-hop address, and is processed normally in Cisco IOS XR BGP. This verification means that the router advertises to its neighbors that it has a route to the prefix, but any traffic received for that prefix is dropped. This “blackholing” effect is often used to automatically protect against Denial of Service (DOS) attacks on user hosts. An inbound policy is configured that sets the next hop to a local address (for example, the address of a loopback interface) when a route with a particular community is received. When a user finds that a host is under a DOS attack, a BGP advertisement is sent to the address of the attacked host with the special community attached. The advertisement causes the Internet service provider (ISP) router to install a route with a local next hop for that address that drops all traffic destined for it. BGP Configuration Cisco IOS XR BGP follows a neighbor-based configuration model that requires that all configurations for a particular neighbor be grouped in one place under the neighbor configuration. Peer groups are not supported for either sharing configuration between neighbors or for sharing update messages. The concept of peer group has been replaced by a set of configuration groups to be used as templates in BGP configuration and automatically generated update groups to share update messages between neighbors. BGP configurations are grouped into four major categories: – Router Configuration Mode – Global Address Family Configuration Mode – Neighbor Configuration Mode – Neighbor Address Family Configuration Mode Configuration Modes The following sections show how to enter each of the configuration modes. From a mode, you can enter the ? command to display the commands available in that mode. Cisco IOS XR Routing Configuration Guide RC-4 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software Router Configuration Mode The following example shows how to enter router configuration mode: RP/0/RP0/CPU0:router# configuration RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# Global Address Family Configuration Mode The following example shows how to enter global address family configuration mode: RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 multicast RP/0/RP0/CPU0:router(config-bgp-af)# Neighbor Configuration Mode The following example shows how to enter neighbor configuration mode: RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.0.1 RP/0/RP0/CPU0:router(config-bgp-nbr)# Neighbor Address Family Configuration Mode The following example shows how to enter neighbor address family configuration mode: RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.0.1 RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicast RP/0/RP0/CPU0:router(config-bgp-nbr-af)# Neighbor Submode Cisco IOS XR BGP uses a neighbor submode to make it possible to enter configurations without having to prefix every configuration with the neighbor keyword and the neighbor address: • Cisco IOS XR software has a submode available for neighbors in which it is not necessary for every command to have a “neighbor x.x.x.x” prefix. In Cisco IOS XR software, the configuration is as follows: Router(config-bgp-af)# neighbor 192.23.1.2 Router(config-bgp-nbr)# remote-as 2002 Router(config-bgp-nbr)# address-family ipv4 multicast • An address family configuration submode inside the neighbor configuration submode is available for entering address family-specific neighbor configurations. In Cisco IOS XR, the configuration is as follows: Router(config-bgp-af)# neighbor 2002::2 Router(config-bgp-nbr)# remote-as 2002 Router(config-bgp-nbr)# address-family ipv6 unicast Router(config-bgp-nbr-af)# next-hop-self Router(config-bgp-nbr-af)# route-policy one in • You must enter neighbor-specific IPv4 or IPv6 commands in neighbor address-family configuration submode. In Cisco IOS XR software, the configuration is as follows: Router(config-bgp)# router bgp 109 Router(config-bgp)# neighbor 192.168.40.24 Cisco IOS XR Routing Configuration Guide RC-5 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software Router(config-bgp-nbr)# remote-as 1 Router(config-bgp-nbr)# address-family ipv4 unicast Router(config-bgp-nbr-af)# maximum-prefix 1000 Configuration Templates The af-group, session-group, and neighbor-group configuration commands provide template support for the neighbor configuration in Cisco IOS XR software: The af-group command is used to group address family-specific neighbor commands within an IPv4 or IPv6 address family. Neighbors that have the same address family configuration are able to use the address family group (af-group) name for their address family-specific configuration. A neighbor inherits the configuration from an address family group by way of the use command. If a neighbor is configured to use an address family group, the neighbor (by default) inherits the entire configuration from the address family group. However, a neighbor does not inherit all of the configuration from the address family group if items are explicitly configured for the neighbor. The address family group configuration is entered under the BGP router configuration mode. The following example shows how to enter address family group configuration mode. RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# af-group afmcast1 address-family ipv4 multicast RP/0/RP0/CPU0:router(config-bgp-afgrp)# The session-group command allows you to create a session group from which neighbors can inherit address family-independent configuration. A neighbor inherits the configuration from a session group by way of the use command. If a neighbor is configured to use a session group, the neighbor (by default) inherits the entire configuration of the session group. A neighbor does not inherit all of the configuration from a session group if a configuration is done directly on that neighbor. The following example shows how to enter session group configuration mode: RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# session-group session1 RP/0/RP0/CPU0:router(config-bgp-sngrp)# The neighbor-group command helps you apply the same configuration to one or more neighbors. Neighbor groups can include session groups and address family groups and can comprise the complete configuration for a neighbor. After a neighbor group is configured, a neighbor can inherit the configuration of the group using the use command. If a neighbor is configured to use a neighbor group, the neighbor inherits the entire BGP configuration of the neighbor group. The following example shows how to enter neighbor group configuration mode: RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# neighbor-group nbrgroup1 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# The following example shows how to enter neighbor group address family configuration mode: RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# neighbor-group nbrgroup1 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# address-family ipv4 unicast RP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# • However, a neighbor does not inherit all of the configuration from the neighbor group if items are explicitly configured for the neighbor. In addition, some part of the configuration of the neighbor group could be hidden if a session group or address family group was also being used. Configuration grouping has the following effects in Cisco IOS XR software: Cisco IOS XR Routing Configuration Guide RC-6 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software • Commands entered at the session group level define address family-independent commands (the same commands as in the neighbor submode). • Commands entered at the address family group level define address family-dependent commands for a specified address family (the same commands as in the neighbor-address family configuration submode). • Commands entered at the neighbor group level define address family-independent commands and address family-dependent commands for each address family (the same as all available neighbor commands), and define the use command for the address family group and session group commands. Template Inheritance Rules In Cisco IOS XR software, BGP neighbors or groups inherit configuration from other configuration groups. For address family-independent configurations: • Neighbors can inherit from session groups and neighbor groups. • Neighbor groups can inherit from session groups and other neighbor groups. • Session groups can inherit from other session groups. • If a neighbor uses a session group and a neighbor group, the configurations in the session group are preferred over the global address family configurations in the neighbor group. For address family-dependent configurations: • Address family groups can inherit from other address family groups. • Neighbor groups can inherit from address family groups and other neighbor groups. • Neighbors can inherit from address family groups and neighbor groups. Configuration group inheritance rules are numbered in order of precedence as follows: 1. If the item is configured directly on the neighbor, that value is used. In the example that follows, the advertisement interval is configured both on the neighbor group and neighbor configuration and the advertisement interval being used is from the neighbor configuration: RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# neighbor-group AS_1 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# advertisement-interval 15 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# exit RP/0/RP0/CPU0:router(config-bgp)# neighbor 10.1.1.1 RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1 RP/0/RP0/CPU0:router(config-bgp-nbr)# use neighbor-group AS_1 RP/0/RP0/CPU0:router(config-bgp-nbr)# advertisement-interval 20 The following output from the show bgp neighbors command shows that the advertisement interval used is 20 seconds: RP/0/RP0/CPU0:router# show bgp neighbors 10.1.1.1 BGP neighbor is 10.1.1.1, remote AS 1, local AS 140, external link Remote router ID 0.0.0.0 BGP state = Idle Last read 00:00:00, hold time is 180, keepalive interval is 60 seconds Received 0 messages, 0 notifications, 0 in queue Sent 0 messages, 0 notifications, 0 in queue Minimum time between advertisement runs is 20 seconds For Address Family: IPv4 Unicast BGP neighbor version 0 Cisco IOS XR Routing Configuration Guide RC-7 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software Update group: 0.1 eBGP neighbor with no inbound or outbound policy; defaults to 'drop' Route refresh request: received 0, sent 0 0 accepted prefixes Prefix advertised 0, suppressed 0, withdrawn 0, maximum limit 524288 Threshold for warning message 75% Connections established 0; dropped 0 Last reset 00:00:14, due to BGP neighbor initialized External BGP neighbor not directly connected. 2. Otherwise, if the neighbor uses a session group or address family group, the configuration value is obtained from the session group or address family group. If the address family group or session group has a parent and an item is configured on the parent, the parent configuration is used. If the item is not configured on the parent, but is configured on the parent ‘s parent, the configuration of the parent’s parent is used, and so on. In the example that follows, the advertisement interval is configured on a neighbor group and a session group and the advertisement interval value being used is from the session group: RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# session-group AS_2 RP/0/RP0/CPU0:router(config-bgp-sngrp)# advertisement-interval 15 RP/0/RP0/CPU0:router(config-bgp-sngrp)# exit RP/0/RP0/CPU0:router(config-bgp)# neighbor-group AS_1 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# advertisement-interval 20 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# exit RP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.0.1 RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1 RP/0/RP0/CPU0:router(config-bgp-nbr)# use session-group AS_2 RP/0/RP0/CPU0:router(config-bgp-nbr)# use neighbor-group AS_1 The following output from the show bgp neighbors command shows that the advertisement interval used is 15 seconds: RP/0/RP0/CPU0:router# show bgp neighbors 192.168.0.1 BGP neighbor is 192.168.0.1, remote AS 1, local AS 140, external link Remote router ID 0.0.0.0 BGP state = Idle Last read 00:00:00, hold time is 180, keepalive interval is 60 seconds Received 0 messages, 0 notifications, 0 in queue Sent 0 messages, 0 notifications, 0 in queue Minimum time between advertisement runs is 15 seconds For Address Family: IPv4 Unicast BGP neighbor version 0 Update group: 0.1 eBGP neighbor with no inbound or outbound policy; defaults to 'drop' Route refresh request: received 0, sent 0 0 accepted prefixes Prefix advertised 0, suppressed 0, withdrawn 0, maximum limit 524288 Threshold for warning message 75% Connections established 0; dropped 0 Last reset 00:03:23, due to BGP neighbor initialized External BGP neighbor not directly connected. 3. Otherwise, if the neighbor uses a neighbor group and does not use a session group or address family group, the configuration value can be obtained from the neighbor group either directly or through inheritance. In the example that follows, the advertisement interval from the neighbor group is used because it is not configured directly on the neighbor and no session group is used: Cisco IOS XR Routing Configuration Guide RC-8 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software RP/0/RP0/CPU0:router(config)# router bgp 150 RP/0/RP0/CPU0:router(config-bgp)# session-group AS_2 RP/0/RP0/CPU0:router(config-bgp-sngrp)# advertisement-interval 20 RP/0/RP0/CPU0:router(config-bgp-sngrp)# exit RP/0/RP0/CPU0:router(config-bgp)# neighbor-group AS_1 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# advertisement-interval 15 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# exit RP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.1.1 RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1 RP/0/RP0/CPU0:router(config-bgp-nbr)# use neighbor-group AS_1 The following output from the show bgp neighbors command shows that the advertisement interval used is 15 seconds: RP/0/RP0/CPU0:router# show bgp neighbors 192.168.1.1 BGP neighbor is 192.168.2.2, remote AS 1, local AS 140, external link Remote router ID 0.0.0.0 BGP state = Idle Last read 00:00:00, hold time is 180, keepalive interval is 60 seconds Received 0 messages, 0 notifications, 0 in queue Sent 0 messages, 0 notifications, 0 in queue Minimum time between advertisement runs is 15 seconds For Address Family: IPv4 Unicast BGP neighbor version 0 Update group: 0.1 eBGP neighbor with no outbound policy; defaults to 'drop' Route refresh request: received 0, sent 0 Inbound path policy configured Policy for incoming advertisements is POLICY_1 0 accepted prefixes Prefix advertised 0, suppressed 0, withdrawn 0, maximum limit 524288 Threshold for warning message 75% Connections established 0; dropped 0 Last reset 00:01:14, due to BGP neighbor initialized External BGP neighbor not directly connected. To illustrate the same rule, the following example shows how to set the advertisement interval to 15 (from the session group). The timers are set to the default (60/180) because the neighbor uses a session group, thus hiding the timers command in the neighbor group. The inbound policy is set to POLICY_1 from the neighbor group. RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# session-group ADV RP/0/RP0/CPU0:router(config-bgp-sngrp)# advertisement-interval 15 RP/0/RP0/CPU0:router(config-bgp-sngrp)# exit RP/0/RP0/CPU0:router(config-bgp)# neighbor-group TIMER RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# timers 10 30 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# address-family ipv4 unicast RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# route-policy POLICY_1 in RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# exit RP/0/RP0/CPU0:router(config-bgp)# exit RP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.2.2 RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1 RP/0/RP0/CPU0:router(config-bgp-nbr)# use session-group ADV RP/0/RP0/CPU0:router(config-bgp-nbr)# use neighbor-group TIMER The following output from the show bgp neighbors command shows that the advertisement interval used is 15 seconds: Cisco IOS XR Routing Configuration Guide RC-9 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software RP/0/RP0/CPU0:router# show bgp neighbors 192.168.2.2 BGP neighbor is 192.168.2.2, remote AS 1, local AS 140, external link Remote router ID 0.0.0.0 BGP state = Idle Last read 00:00:00, hold time is 180, keepalive interval is 60 seconds Received 0 messages, 0 notifications, 0 in queue Sent 0 messages, 0 notifications, 0 in queue Minimum time between advertisement runs is 15 seconds For Address Family: IPv4 Unicast BGP neighbor version 0 Update group: 0.1 eBGP neighbor with no inbound or outbound policy; defaults to 'drop' Route refresh request: received 0, sent 0 0 accepted prefixes Prefix advertised 0, suppressed 0, withdrawn 0, maximum limit 524288 Threshold for warning message 75% Connections established 0; dropped 0 Last reset 00:02:03, due to BGP neighbor initialized External BGP neighbor not directly connected. 4. Otherwise, the default value is used. In the example that follows, neighbor 10.0.101.5 has the minimum time between advertisement runs set to 30 seconds (default) because the neighbor is not configured to use the neighbor configuration or the neighbor group configuration: RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# neighbor-group AS_1 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# remote-as 1 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# exit RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# neighbor-group adv_15 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# remote-as 10 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# advertisement-interval 15 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# exit RP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.101.5 RP/0/RP0/CPU0:router(config-bgp-nbr)# use neighbor-group AS_1 RP/0/RP0/CPU0:router(config-bgp-nbr)# exit RP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.101.10 RP/0/RP0/CPU0:router(config-bgp-nbr)# use neighbor-group adv_15 The following output from the show bgp neighbors command shows that the advertisement interval used is 30 seconds: RP/0/RP0/CPU0:router# show bgp neighbors 10.0.101.5 BGP neighbor is 10.0.101.5, remote AS 1, local AS 140, external link Remote router ID 0.0.0.0 BGP state = Idle Last read 00:00:00, hold time is 180, keepalive interval is 60 seconds Received 0 messages, 0 notifications, 0 in queue Sent 0 messages, 0 notifications, 0 in queue Minimum time between advertisement runs is 30 seconds For Address Family: IPv4 Unicast BGP neighbor version 0 Update group: 0.2 eBGP neighbor with no inbound or outbound policy; defaults to 'drop' Route refresh request: received 0, sent 0 0 accepted prefixes Prefix advertised 0, suppressed 0, withdrawn 0, maximum limit 524288 Threshold for warning message 75% Connections established 0; dropped 0 Cisco IOS XR Routing Configuration Guide RC-10 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software Last reset 00:00:25, due to BGP neighbor initialized External BGP neighbor not directly connected. The inheritance rules used when groups are inheriting configuration from other groups are the same as the rules given for neighbors inheriting from groups. Template Inheritance You can use the following show commands described to monitor BGP inheritance information: • show bgp neighbors, page RC-11 • show bgp af-group, page RC-12 • show bgp session-group, page RC-13 • show bgp neighbor-group, page RC-14 show bgp neighbors Use the show bgp neighbors command to display information about the BGP configuration for neighbors. • Use the configuration keyword to display the effective configuration for the neighbor, including any settings that have been inherited from session groups, neighbor groups, or address family groups used by this neighbor. • Use the inheritance keyword to display the session groups, neighbor groups, and address family groups from which this neighbor is capable of inheriting configuration . The show bgp neighbors command examples that follow are based on the sample configuration: RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# af-group GROUP_3 address-family ipv4 unicast RP/0/RP0/CPU0:router(config-bgp-afgrp)# next-hop-self RP/0/RP0/CPU0:router(config-bgp-afgrp)# route-policy POLICY_1 in RP/0/RP0/CPU0:router(config-bgp0afgrp)# exit RP/0/RP0/CPU0:router(config-bgp)# session-group GROUP_2 RP/0/RP0/CPU0:router(config-bgp-sngrp)# advertisement-interval 15 RP/0/RP0/CPU0:router(config-bgp-sngrp)# exit RP/0/RP0/CPU0:router(config-bgp)# neighbor-group GROUP_1 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# use session-group GROUP_2 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# ebgp-multihop 3 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# address-family ipv4 unicast RP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# weight 100 RP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# send-community-ebgp RP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# exit RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# address-family ipv4 multicast RP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# default-originate RP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# exit RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# exit RP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.0.1 RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 2 RP/0/RP0/CPU0:router(config-bgp-nbr)# use neighbor-group GROUP_1 RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicast RP/0/RP0/CPU0:router(config-bgp-nbr-af)# use af-group GROUP_3 RP/0/RP0/CPU0:router(config-bgp-nbr-af)# weight 200 Cisco IOS XR Routing Configuration Guide RC-11 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software The following example displays sample output from the show bgp neighbors command using the inheritance keyword. The example shows that the neighbor inherits session parameters from neighbor group GROUP_1, which in turn inherits from session group GROUP_2. The neighbor inherits IPv4 unicast parameters from address family group GROUP_3 and IPv4 multicast parameters from neighbor group GROUP_1: RP/0/RP0/CPU0:router# show bgp neighbors 192.168.0.1 inheritance Session: n:GROUP_1 s:GROUP_2 IPv4 Unicast: a:GROUP_3 IPv4 Multicast: n:GROUP_1 The following example displays sample output from the show bgp neighbors command using the configuration keyword. The example shows from where each item of configuration was inherited, or if it was configured directly on the neighbor (indicated by [ ]). For example, the ebgp-multihop 3 command was inherited from neighbor group GROUP_1 and the next-hop-self command was inherited from the address family group GROUP_3: RP/0/RP0/CPU0:router# show bgp neighbors 192.168.0.1 configuration neighbor 192.168.0.1 remote-as 2 advertisement-interval 15 ebgp-multihop 3 address-family ipv4 unicast next-hop-self route-policy POLICY_1 in weight 200 address-family ipv4 multicast default-originate [] [n:GROUP_1 s:GROUP_2] [n:GROUP_1] [] [a:GROUP_3] [a:GROUP_3] [] [n:GROUP_1] [n:GROUP_1] show bgp af-group Use the show bgp af-group command to display address family groups: • Use the configuration keyword to display the effective configuration for the address family group, including any settings that have been inherited from address family groups used by this address family group. • Use the inheritance keyword to display the address family groups from which this address family group is capable of inheriting configuration. • Use the users keyword to display the neighbors, neighbor groups, and address family groups that inherit configuration from this address family group. The show bgp af-group command examples that follow are based on the this sample configuration: RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# af-group GROUP_3 address-family ipv4 unicast RP/0/RP0/CPU0:router(config-bgp-afgrp)# remove-private-as RP/0/RP0/CPU0:router(config-bgp-afgrp)# route-policy POLICY_1 in RP/0/RP0/CPU0:router(config-bgp-afgrp)# exit RP/0/RP0/CPU0:router(config-bgp)# af-group GROUP_1 address-family ipv4 unicast RP/0/RP0/CPU0:router(config-bgp-afgrp)# use af-group GROUP_2 RP/0/RP0/CPU0:router(config-bgp-afgrp)# maximum-prefix 2500 75 warning-only RP/0/RP0/CPU0:router(config-bgp-afgrp)# default-originate RP/0/RP0/CPU0:router(config-bgp-afgrp)# exit RP/0/RP0/CPU0:router(config-bgp)# af-group GROUP_2 address-family ipv4 unicast RP/0/RP0/CPU0:router(config-bgp-afgrp)# use af-group GROUP_3 RP/0/RP0/CPU0:router(config-bgp-afgrp)# send-community-ebgp RP/0/RP0/CPU0:router(config-bgp-afgrp)# send-extended-community-ebgp RP/0/RP0/CPU0:router(config-bgp-afgrp)# capability orf prefix-list both Cisco IOS XR Routing Configuration Guide RC-12 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software The following example displays sample output from the show bgp af-group command using the configuration keyword. This example shows from where each configuration item was inherited. The default-originate command was configured directly on this address family group (indicated by [ ]). The remove-private-as command was inherited from address family group GROUP_2, which in turn inherited from address family group GROUP_3: RP/0/RP0/CPU0:router# show bgp af-group GROUP_1 configuration af-group GROUP_1 address-family ipv4 unicast capability orf prefix-list both [a:GROUP_2] default-originate [] maximum-prefix 2500 75 warning-only [] route-policy POLICY_1 in [a:GROUP_2 a:GROUP_3] remove-private-AS [a:GROUP_2 a:GROUP_3] send-community-ebgp [a:GROUP_2] send-extended-community-ebgp [a:GROUP_2] The following example displays sample output from the show bgp af-group command using the users keyword: RP/0/RP0/CPU0:router# show bgp af-group GROUP_2 users IPv4 Unicast: a:GROUP_1 The following example displays sample output from the show bgp af-group command using the inheritance keyword. This shows that the specified address family group GROUP_1 directly uses the GROUP_2 address family group, which in turn uses the GROUP_3 address family group: RP/0/RP0/CPU0:router# show bgp af-group GROUP_1 inheritance IPv4 Unicast: a:GROUP_2 a:GROUP_3 show bgp session-group Use the show bgp session-group command to display session groups: • Use the configuration keyword to display the effective configuration for the session group, including any settings that have been inherited from session groups used by this session group. • Use the inheritance keyword to display the session groups from which this session group is capable of inheriting configuration. • Use the users keyword to display the session groups, neighbor groups, and neighbors that inherit configuration from this session group. The examples that follow sample output from the show bgp session-group command with the configuration keyword in EXEC mode. The examples are based on the following session group configuration: RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# session-group GROUP_1 RP/0/RP0/CPU0:router(config-bgp-sngrp)# use session-group GROUP_2 RP/0/RP0/CPU0:router(config-bgp-sngrp)# update-source Loopback 0 RP/0/RP0/CPU0:router(config-bgp-sngrp)# exit RP/0/RP0/CPU0:router(config-bgp)# session-group GROUP_2 RP/0/RP0/CPU0:router(config-bgp-sngrp)# use session-group GROUP_3 RP/0/RP0/CPU0:router(config-bgp-sngrp)# ebgp-multihop 2 RP/0/RP0/CPU0:router(config-bgp-sngrp)# exit RP/0/RP0/CPU0:router(config-bgp)# session-group GROUP_3 RP/0/RP0/CPU0:router(config-bgp-sngrp)# dmz-link-bandwidth The following is sample output from the show bgp session-group command with the configuration keyword in EXEC mode: Cisco IOS XR Routing Configuration Guide RC-13 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software RP/0/RP0/CPU0:router# show bgp session-group GROUP_1 configuration session-group GROUP_1 ebgp-multihop 2 [s:GROUP_2] update-source Loopback0 [] dmz-link-bandwidth [s:GROUP_2 s:GROUP_3] The following is sample output from the show bgp session-group command with the inheritance keyword showing that the GROUP_1 session group inherits session parameters from the GROUP_3 and GROUP_2 session groups: RP/0/RP0/CPU0:router# show bgp session-group GROUP_1 inheritance Session: s:GROUP_2 s:GROUP_3 The following is sample output from the show bgp session-group command with the users keyword showing that both the GROUP_1 and GROUP_2 session groups inherit session parameters from the GROUP_3 session group: RP/0/RP0/CPU0:router# show bgp session-group GROUP_3 users Session: s:GROUP_1 s:GROUP_2 show bgp neighbor-group Use the show bgp neighbor-group command to display neighbor groups: • Use the configuration keyword to display the effective configuration for the neighbor group, including any settings that have been inherited from neighbor groups used by this neighbor group. • Use the inheritance keyword to display the address family groups, session groups, and neighbor groups from which this neighbor group is capable of inheriting configuration. • Use the users keyword to display the neighbors and neighbor groups that inherit configuration from this neighbor group. The examples are based on the following group configuration: RP/0/RP0/CPU0:router(config)# router bgp 140 RP/0/RP0/CPU0:router(config-bgp)# af-group GROUP_3 address-family ipv4 unicast RP/0/RP0/CPU0:router(config-bgp-afgrp)# remove-private-as RP/0/RP0/CPU0:router(config-bgp-afgrp)# soft-reconfiguration inbound RP/0/RP0/CPU0:router(config-bgp-afgrp)# exit RP/0/RP0/CPU0:router(config-bgp)# af-group GROUP_2 address-family ipv4 unicast RP/0/RP0/CPU0:router(config-bgp-afgrp)# use af-group GROUP_3 RP/0/RP0/CPU0:router(config-bgp-afgrp)# send-community-ebgp RP/0/RP0/CPU0:router(config-bgp-afgrp)# send-extended-community-ebgp RP/0/RP0/CPU0:router(config-bgp-afgrp)# capability orf prefix-list both RP/0/RP0/CPU0:router(config-bgp-afgrp)# exit RP/0/RP0/CPU0:router(config-bgp)# session-group GROUP_3 RP/0/RP0/CPU0:router(config-bgp-sngrp)# timers 30 90 RP/0/RP0/CPU0:router(config-bgp-sngrp)# exit RP/0/RP0/CPU0:router(config-bgp)# neighbor-group GROUP_1 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# remote-as 1982 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# use neighbor-group GROUP_2 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# address-family ipv4 unicast RP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# exit RP/0/RP0/CPU0:router(config-nbrgrp)# exit RP/0/RP0/CPU0:router(config-bgp)# neighbor-group GROUP_2 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# use session-group GROUP_3 RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# address-family ipv4 unicast RP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# use af-group GROUP_2 RP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# weight 100 Cisco IOS XR Routing Configuration Guide RC-14 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software The following is sample output from the show bgp neighbor-group command with the configuration keyword. The configuration setting source is shown to the right of each command. In the output shown previously, the remote autonomous system is configured directly on neighbor group GROUP_1, and the send community setting is inherited from neighbor group GROUP_2, which in turn inherits the setting from address family group GROUP_3: RP/0/RP0/CPU0:router# show bgp neighbor-group GROUP_1 configuration neighbor-group GROUP_1 remote-as 1982 timers 30 90 address-family ipv4 unicast capability orf prefix-list both remove-private-AS send-community-ebgp send-extended-community-ebgp soft-reconfiguration inbound weight 100 [] [n:GROUP_2 s:GROUP_3] [] [n:GROUP_2 a:GROUP_2] [n:GROUP_2 a:GROUP_2 a:GROUP_3] [n:GROUP_2 a:GROUP_2] [n:GROUP_2 a:GROUP_2] [n:GROUP_2 a:GROUP_2 a:GROUP_3] [n:GROUP_2] The following is sample output from the show bgp neighbor-group command with the inheritance keyword. This output shows that the specified neighbor group GROUP_1 inherits session (address family-independent) configuration parameters from neighbor group GROUP_2. Neighbor group GROUP_2 inherits its session parameters from session group GROUP_3. It also shows that the GROUP_1 neighbor group inherits IPv4 unicast configuration parameters from the GROUP_2 neighbor group, which in turn inherits them from the GROUP_2 address family group, which itself inherits them from the GROUP_3 address family group: RP/0/RP0/CPU0:router# show bgp neighbor-group GROUP_1 inheritance Session: n:GROUP-2 s:GROUP_3 IPv4 Unicast: n:GROUP_2 a:GROUP_2 a:GROUP_3 The following is sample output from the show bgp neighbor-group command with the users keyword. This output shows that the GROUP_1 neighbor group inherits session (address family-independent) configuration parameters from the GROUP_2 neighbor group. The GROUP_1 neighbor group also inherits IPv4 unicast configuration parameters from the GROUP_2 neighbor group: RP/0/RP0/CPU0:router# show bgp neighbor-group GROUP_2 users Session: n:GROUP_1 IPv4 Unicast: n:GROUP_1 No Default Address Family BGP does not support the concept of a default address family. An address family must be explicitly configured under the BGP router configuration for the address family to be activated in BGP. Similarly, an address family must be explicitly configured under a neighbor for the BGP session to be activated under that address family. It is not required to have any address family configured under the BGP router configuration level for a neighbor to be configured. However, it is a requirement to have an address family configured at the BGP router configuration level for the address family to be configured under a neighbor. Cisco IOS XR Routing Configuration Guide RC-15 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software Routing Policy Enforcement External BGP (eBGP) neighbors must have an inbound and outbound policy configured. If no policy is configured, no routes are accepted from the neighbor, nor are any routes advertised to it. This added security measure ensures that routes cannot accidentally be accepted or advertised in the case of a configuration omission error. Note This enforcement affects only eBGP neighbors (neighbors in a different autonomous system than this router). For internal BGP (iBGP) neighbors (neighbors in the same autonomous system), all routes are accepted or advertised if there is no policy. In the following example, for an eBGP neighbor, if all routes should be accepted and advertised with no modifications, a simple pass-all policy is configured: RP/0/RP0/CPU0:router(config)# route-policy pass-all RP/0/RP0/CPU0:router(config-rpl)# pass RP/0/RP0/CPU0:router(config-rpl)# end-policy RP/0/RP0/CPU0:router(config)# commit Use the route-policy (BGP) command in the neighbor address-family configuration mode to apply the pass-all policy to a neighbor. The following example shows how to allow all IPv4 unicast routes to be received from neighbor 192.168.40.42 and advertise all IPv4 unicast routes back to it: RP/0/RP0/CPU0:router(config)# router bgp 1 RP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.40.24 RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 2 RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicast RP/0/RP0/CPU0:router(config-bgp-nbr-af)# route-policy pass-all in RP/0/RP0/CPU0:router(config-bgp-nbr-af)# route-policy pass-all out RP/0/RP0/CPU0:router(config-bgp-nbr-af)# commit Use the show bgp summary command to display eBGP neighbors that do not have both an inbound and outbound policy for every active address family. In the following example, such eBGP neighbors are indicated in the output with an exclamation (!) mark: RP/0/RP0/CPU0:router# show bgp all all summary Address Family: IPv4 Unicast ============================ BGP BGP BGP BGP BGP router identifier 10.0.0.1, local AS number 1 generic scan interval 60 secs main routing table version 41 scan interval 60 secs is operating in STANDALONE mode. Process Speaker RecvTblVer 41 Neighbor 10.0.101.1 10.0.101.2 Spk 0 0 bRIB/RIB 41 SendTblVer 41 AS MsgRcvd MsgSent 1 919 925 2 0 0 TblVer 41 0 Address Family: IPv4 Multicast ============================== BGP router identifier 10.0.0.1, local AS number 1 BGP generic scan interval 60 secs BGP main routing table version 1 Cisco IOS XR Routing Configuration Guide RC-16 InQ OutQ Up/Down St/PfxRcd 0 0 15:15:08 10 0 0 00:00:00 Idle Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software BGP scan interval 60 secs BGP is operating in STANDALONE mode. Process Speaker RecvTblVer 1 bRIB/RIB 1 SendTblVer 1 Some configured eBGP neighbors do not have both inbound and outbound policies configured for IPv4 Multicast address family. These neighbors will default to sending and/or receiving no routes and are marked with ’!’ in the output below. Use the ’show bgp neighbor’ command for details. Neighbor 10.0.101.2 Spk 0 AS MsgRcvd MsgSent 2 0 0 TblVer 0 InQ OutQ Up/Down St/PfxRcd 0 0 00:00:00 Idle! Address Family: IPv6 Unicast ============================ BGP BGP BGP BGP BGP router identifier 10.0.0.1, local AS number 1 generic scan interval 60 secs main routing table version 2 scan interval 60 secs is operating in STANDALONE mode. Process Speaker RecvTblVer 2 Neighbor 2222::2 2222::4 Spk 0 0 bRIB/RIB 2 SendTblVer 2 AS MsgRcvd MsgSent 2 920 918 3 0 0 TblVer 2 0 InQ OutQ Up/Down St/PfxRcd 0 0 15:15:11 1 0 0 00:00:00 Idle Address Family: IPv6 Multicast ============================== BGP BGP BGP BGP BGP router identifier 10.0.0.1, local AS number 1 generic scan interval 60 secs main routing table version 1 scan interval 60 secs is operating in STANDALONE mode. Process Speaker RecvTblVer 1 bRIB/RIB 1 SendTblVer 1 Some configured eBGP neighbors do not have both inbound and outbound policies configured for IPv6 Multicast address family. These neighbors will default to sending and/or receiving no routes and are marked with ’!’ in the output below. Use the ’show bgp neighbor ’ command for details. Neighbor 2222::2 2222::4 Spk 0 0 AS MsgRcvd MsgSent 2 920 918 3 0 0 TblVer 0 0 InQ OutQ Up/Down St/PfxRcd 0 0 15:15:11 0 0 0 00:00:00 Idle! Cisco IOS XR Routing Configuration Guide RC-17 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software Table Policy The table policy feature in BGP allows you to configure traffic index values on routes as they are installed in the global routing table. This feature is enabled using the table-policy command and supports the BGP policy accounting feature. BGP policy accounting uses traffic indices that are set on BGP routes to track various counters. See Implementing Routing Policy on Cisco IOS XR Software for details on table policy use. See the Cisco Express Forwarding Commands on Cisco IOS XR Software module in the Cisco IOS XR IP Addresses and Services Command Reference for details on BGP policy accounting. Table policy also provides the ability to drop routes from the RIB based on match criteria. This feature can be useful in certain applications and should be used with caution as it can easily create a routing ‘black-hole’ where BGP advertises routes to neighbors that BGP does not install in its global routing table but in the forwarding table . Update Groups The BGP Update Groups feature contains an algorithm that dynamically calculates and optimizes update groups of neighbors that share outbound policies and can share the update messages. The BGP Update Groups feature separates update group replication from peer group configuration, improving convergence time and flexibility of neighbor configuration. To use this feature, you must understand the following concepts: • BGP Update Generation and Update Groups, page RC-18 • BGP Update Group, page RC-18 BGP Update Generation and Update Groups The BGP Update Groups feature separates BGP update generation from neighbor configuration. The BGP Update Groups feature introduces an algorithm that dynamically calculates BGP update group membership based on outbound routing policies. This feature does not require any configuration by the network operator. Update group-based message generation occurs automatically and independently. BGP Update Group When a change to the configuration occurs, the router automatically recalculates update group memberships and applies the changes. For the best optimization of BGP update group generation, we recommend that the network operator keeps outbound routing policy the same for neighbors that have similar outbound policies. This feature contains commands for monitoring BGP update groups. For more information about the commands, see the “Monitoring BGP Update Groups” section on page RC-75. BGP Best Path Algorithm BGP routers typically receive multiple paths to the same destination. The BGP best path algorithm determines the best path to install in the IP routing table and to use for forwarding traffic. This section describes the IOS XR implementation of BGP best path algorithm, as specified in Section 9.1 of the Internet Engineering Task Force (IETF) Network Working Group draft-ietf-idr-bgp4-24.txt document. Cisco IOS XR Routing Configuration Guide RC-18 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software The BGP best path algorithm implementation is in three parts: Note • Part 1—Compares two paths to determine which is better. • Part 2—Iterates over all paths and determines which order to compare the paths to select the overall best path. • Part 3—Determines whether the old and new best paths differ enough so that the new best path should be used. The order of comparison determined by Part 2 is important because the comparison operation is not transitive; that is, if three paths, A, B, and C exist, such that when A and B are compared, A is better, and when B and C are compared, B is better, it is not necessarily the case that when A and C are compared, A is better. This nontransitivity arises because the multi exit discriminator (MED) is compared only among paths from the same neighboring autonomous system (AS) and not among all paths. Comparing Pairs of Paths The following steps are completed to compare two paths and determine the better path: Note 1. If either path is invalid (for example, it has the maximum possible MED value, or it has an unreachable nexthop), then the other path is chosen (provided that the path is valid). 2. If the paths have unequal weights, the path with the highest weight is chosen. Note: the weight is entirely local to the router, and can be set with the weight command or using a routing policy. 3. If the paths have unequal local preferences, the path with the higher local preference is chosen. Note: If a local preference attribute was received with the path or was set by a routing policy, then that value is used in this comparison. Otherwise, the default local preference value of 100 is used. The default value can be changed using the bgp default local-preference command. 4. If one of the paths is a redistributed path, which results from a redistribute or network command, then it is chosen. Otherwise, if one of the paths is a locally generated aggregate, which results from an aggregate-address command, it is chosen. Steps 1 through 4 implement the “Degree of Preference” calculation from Section 9.1.1 of draft-ietf-idr-bgp4-24.txt. 5. If the paths have unequal AS path lengths, the path with the shorter AS path is chosen. This step is skipped if bgp bestpath as-path ignore command is configured. Note: when calculating the length of the AS path, confederation segments are ignored, and AS sets count as 1. (See Section 9.1.2.2a of draft-ietf-idr-bgp4-24.txt.) 6. If the paths have different origins, the path with the lower origin is selected. Interior Gateway Protocol (IGP) is considered lower than EGP, which is considered lower than INCOMPLETE. (See Section 9.1.2.2b of draft-ietf-idr-bgp4-24.txt.) 7. If appropriate, the MED of the paths is compared. If they are unequal, the path with the lower MED is chosen. A number of configuration options exist that affect whether or not this step is performed. In general, the MED is compared if both paths were received from neighbors in the same AS; otherwise the MED comparison is skipped. However, this behavior is modified by certain configuration options, and there are also some corner cases to consider. (See Section 9.1.2.2c of draft-ietf-idr-bgp4-24.txt.) Cisco IOS XR Routing Configuration Guide RC-19 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software If the bgp bestpath med always command is configured, then the MED comparison is always performed, regardless of neighbor AS in the paths. Otherwise, MED comparison depends on the AS paths of the two paths being compared, as follows: a. If a path has no AS path or the AS path starts with an AS_SET, then the path is considered to be internal, and the MED is compared with other internal paths b. If the AS path starts with an AS_SEQUENCE, then the neighbor AS is the first AS number in the sequence, and the MED is compared with other paths that have the same neighbor AS c. If the AS path contains only confederation segments or starts with confederation segments followed by an AS_SET, then the MED is not compared with any other path unless the bgp bestpath med confed command is configured. In that case, the path is considered internal and the MED is compared with other internal paths. d. If the AS path starts with confederation segments followed by an AS_SEQUENCE, then the neighbor AS is the first AS number in the AS_SEQUENCE, and the MED is compared with other paths that have the same neighbor AS. Note: if no MED attribute was received with the path, then the MED is considered to be 0 unless the bgp bestpath med missing-as-worst command is configured. In that case, if no MED attribute was received, the MED is considered to be the highest possible value. 8. If one path is received from an external peer and the other is received from an internal (or confederation) peer, the path from the external peer is chosen. (See Section 9.1.2.2d of draft-ietf-idr-bgp4-24.txt.) 9. If the paths have different IGP metrics to their next hops, the path with the lower IGP metric is chosen. (See Section 9.1.2.2e of draft-ietf-idr-bgp4-24.txt.) 10. If all path parameters in steps 1 through 10 are the same, then the router IDs are compared. If the path was received with an originator attribute, then that is used as the router ID to compare; otherwise, the router ID of the neighbor from which the path was received is used. If the paths have different router IDs, the path with the lower router ID is chosen. Note: where the originator is used as the router ID, it is possible to have two paths with the same router ID. It is also possible to have two BGP sessions with the same peer router, and therefore receive two paths with the same router ID. (See Section 9.1.2.2f of draft-ietf-idr-bgp4-24.txt.) 11. If the paths have different cluster lengths, the path with the shorter cluster length is selected. If a path was not received with a cluster list attribute, it is considered to have a cluster length of 0. 12. Finally, the path received from the neighbor with the lower IP address is chosen. Locally generated paths (for example, redistributed paths) are considered to have a neighbor IP address of 0. (See Section 9.1.2.2g of draft-ietf-idr-bgp4-24.txt.) Order of Comparisons The second part of the BGP best path algorithm implementation determines the order in which the paths should be compared. The order of comparison is determined as follows: 1. The paths are partitioned into groups such that within each group the MED can be compared among all paths. The same rules as in the “Comparing Pairs of Paths” section on page RC-19 are used to determine whether MED can be compared between any two paths. Normally, this comparison results in one group for each neighbor AS. If the bgp bestpath med always command is configured, then there is just one group containing all the paths. Cisco IOS XR Routing Configuration Guide RC-20 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software 2. The best path in each group is determined. Determining the best path is achieved by iterating through all paths in the group and keeping track of the best one seen so far. Each path is compared with the best-so-far, and if it is better, it becomes the new best-so-far and is compared with the next path in the group. 3. A set of paths is formed containing the best path selected from each group in step 2. The overall best path is selected from this set of paths, by iterating through them as in step 2. Best Path Change Suppression The third part of the implementation is to determine whether the best path change can be suppressed or not—whether the new best path should be used, or continue using the existing best path. The existing best path can continue to be used if the new one is identical to the point at which the best path selection algorithm becomes arbitrary (if the router-id is the same). Continuing to use the existing best path can avoid churn in the network. Note This suppression behavior does not comply with the IETF Networking Working Group draft-ietf-idr-bgp4-24.txt document, but is specified in the IETF Networking Working Group draft-ietf-idr-avoid-transition-00.txt document. The suppression behavior can be turned off by configuring the bgp bestpath compare-routerid command. If this command is configured, the new best path is always preferred to the existing one. Otherwise, the following steps are used to determine whether the best path change can be suppressed: 1. If the existing best path is no longer valid, the change cannot be suppressed. 2. If either the existing or new best paths were received from internal (or confederation) peers or were locally generated (for example, by redistribution), then the change cannot be suppressed. That is, suppression is possible only if both paths were received from external peers. 3. If the paths were received from the same peer (the paths would have the same router-id), the change cannot be suppressed. The router ID is calculated using rules in the “Comparing Pairs of Paths” section on page RC-19. 4. If the paths have different weights, local preferences, origins, or IGP metrics to their next hops, then the change cannot be suppressed. Note that all of these values are calculated using the rules in the “Comparing Pairs of Paths” section on page RC-19. 5. If the paths have different-length AS paths and the bgp bestpath as-path ignore command is not configured, then the change cannot be suppressed. Again, the AS path length is calculated using the rules in the “Comparing Pairs of Paths” section on page RC-19. 6. If the MED of the paths can be compared and the MEDs are different, then the change cannot be suppressed. The decision as to whether the MEDs can be compared is exactly the same as the rules in the “Comparing Pairs of Paths” section on page RC-19, as is the calculation of the MED value. 7. If all path parameters in steps 1 through 6 do not apply, the change can be suppressed. Multiprotocol BGP Multiprotocol BGP is an enhanced BGP that carries routing information for multiple network layer protocols and IP multicast routes. BGP carries two sets of routes, one set for unicast routing and one set for multicast routing. The routes associated with multicast routing are used by the Protocol Independent Multicast (PIM) feature to build data distribution trees. Cisco IOS XR Routing Configuration Guide RC-21 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software Multiprotocol BGP is useful when you want a link dedicated to multicast traffic, perhaps to limit which resources are used for which traffic. Multiprotocol BGP allows you to have a unicast routing topology different from a multicast routing topology providing more control over your network and resources. In BGP, the only way to perform interdomain multicast routing was to use the BGP infrastructure that was in place for unicast routing. Perhaps you want all multicast traffic exchanged at one network access point (NAP). If those routers were not multicast capable, or there were differing policies for which you wanted multicast traffic to flow, multicast routing could not be supported without multiprotocol BGP. Note It is possible to configure BGP peers that exchange both unicast and multicast network layer reachability information (NLRI), but you cannot connect multiprotocol BGP clouds with a BGP cloud. That is, you cannot redistribute multiprotocol BGP routes into BGP. Figure 1 illustrates simple unicast and multicast topologies that are incongruent, and therefore are not possible without multiprotocol BGP. Autonomous systems 100, 200, and 300 are each connected to two NAPs that are FDDI rings. One is used for unicast peering (and therefore the exchange of unicast traffic). The Multicast Friendly Interconnect (MFI) ring is used for multicast peering (and therefore the exchange of multicast traffic). Each router is unicast and multicast capable. Figure 1 Incongruent Unicast and Multicast Routes FDDI FDDI Unicast MFI AS 200 AS 300 ISP A ISP B ISP C 12238 AS 100 Figure 2 is a topology of unicast-only routers and multicast-only routers. The two routers on the left are unicast-only routers (that is, they do not support or are not configured to perform multicast routing). The two routers on the right are multicast-only routers. Routers A and B support both unicast and multicast routing. The unicast-only and multicast-only routers are connected to a single NAP. In Figure 2, only unicast traffic can travel from Router A to the unicast routers to Router B and back. Multicast traffic could not flow on that path, so another routing table is required. Multicast traffic uses the path from Router A to the multicast routers to Router B and back. Figure 2 illustrates a multiprotocol BGP environment with a separate unicast route and multicast route from Router A to Router B. Multiprotocol BGP allows these routes to be incongruent. Both of the autonomous systems must be configured for internal multiprotocol BGP (IMBGP) in the figure. Cisco IOS XR Routing Configuration Guide RC-22 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software A multicast routing protocol, such as PIM, uses the multicast BGP database to perform Reverse Path Forwarding (RPF) lookups for multicast-capable sources. Thus, packets can be sent and accepted on the multicast topology but not on the unicast topology. Figure 2 Multicast BGP Environment Router B AS 200 Unicast router IMBGP Multicast router NAP Unicast router IMBGP Multicast router AS 100 Unicast route Router A 11754 Multicast route Route Dampening Route dampening is a BGP feature that minimizes the propagation of flapping routes across an internetwork. A route is considered to be flapping when it is repeatedly available, then unavailable, then available, then unavailable, and so on. For example, consider a network with three BGP autonomous systems: autonomous system 1, autonomous system 2, and autonomous system 3. Suppose the route to network A in autonomous system 1 flaps (it becomes unavailable). Under circumstances without route dampening, the eBGP neighbor of autonomous system 1 to autonomous system 2 sends a withdraw message to autonomous system 2. The border router in autonomous system 2, in turn, propagates the withdrawal message to autonomous system 3. When the route to network A reappears, autonomous system 1 sends an advertisement message to autonomous system 2, which sends it to autonomous system 3. If the route to network A repeatedly becomes unavailable, then available, many withdrawal and advertisement messages are sent. Route flapping is a problem in an internetwork connected to the Internet because a route flap in the Internet backbone usually involves many routes. Cisco IOS XR Routing Configuration Guide RC-23 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software Note No penalty is applied to a BGP peer reset when route dampening is enabled. Although the reset withdraws the route, no penalty is applied in this instance, even if route flap dampening is enabled. Minimizing Flapping The route dampening feature minimizes the flapping problem as follows. Suppose again that the route to network A flaps. The router in autonomous system 2 (in which route dampening is enabled) assigns network A a penalty of 1000 and moves it to history state. The router in autonomous system 2 continues to advertise the status of the route to neighbors. The penalties are cumulative. When the route flaps so often that the penalty exceeds a configurable suppression limit, the router stops advertising the route to network A, regardless of how many times it flaps. Thus, the route is dampened. The penalty placed on network A is decayed until the reuse limit is reached, upon which the route is once again advertised. At half of the reuse limit, the dampening information for the route to network A is removed. BGP Routing Domain Confederation One way to reduce the iBGP mesh is to divide an autonomous system into multiple subautonomous systems and group them into a single confederation. To the outside world, the confederation looks like a single autonomous system. Each autonomous system is fully meshed within itself and has a few connections to other autonomous systems in the same confederation. Although the peers in different autonomous systems have eBGP sessions, they exchange routing information as if they were iBGP peers. Specifically, the next hop, MED, and local preference information is preserved. This feature allows the you to retain a single IGP for all of the autonomous systems. BGP Route Reflectors BGP requires that all iBGP speakers be fully meshed. However, this requirement does not scale well when there are many iBGP speakers. Instead of configuring a confederation, another way to reduce the iBGP mesh is to configure a route reflector. Figure 3 illustrates a simple iBGP configuration with three iBGP speakers (routers A, B, and C). Without route reflectors, when Router A receives a route from an external neighbor, it must advertise it to both routers B and C. Routers B and C do not readvertise the iBGP learned route to other iBGP speakers because the routers do not pass on routes learned from internal neighbors to other internal neighbors, thus preventing a routing information loop. Cisco IOS XR Routing Configuration Guide RC-24 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software Figure 3 Three Fully Meshed iBGP Speakers Fully meshed autonomous system Router C Routes Router A Routes advertised External BGP speaker Routes not advertised Router A Routes S4217 Router B With route reflectors, all iBGP speakers need not be fully meshed because there is a method to pass learned routes to neighbors. In this model, an iBGP peer is configured to be a route reflector responsible for passing iBGP learned routes to a set of iBGP neighbors. In Figure 4, Router B is configured as a route reflector. When the route reflector receives routes advertised from Router A, it advertises them to Router C, and vice versa. This scheme eliminates the need for the iBGP session between routers A and C. Figure 4 Simple BGP Model with a Route Reflector Partially meshed autonomous system Routes Router A Router C External BGP speaker Routes Reflected routes S4219 Router A Router B Route reflector The internal peers of the route reflector are divided into two groups: client peers and all other routers in the autonomous system (nonclient peers). A route reflector reflects routes between these two groups. The route reflector and its client peers form a cluster. The nonclient peers must be fully meshed with each other, but the client peers need not be fully meshed. The clients in the cluster do not communicate with iBGP speakers outside their cluster. Cisco IOS XR Routing Configuration Guide RC-25 Implementing BGP on Cisco IOS XR Software Information About Implementing BGP on Cisco IOS XR Software Figure 5 More Complex BGP Route Reflector Model Partially meshed autonomous system Nonclient Router G Route reflector Router A Routes advertised Nonclient Router F Router A External BGP speaker Nonclient Cluster S4218 Router E Router B Client Router C Client Router D Client Figure 5 illustrates a more complex route reflector scheme. Router A is the route reflector in a cluster with routers B, C, and D. Routers E, F, and G are fully meshed, nonclient routers. When the route reflector receives an advertised route, depending on the neighbor, it takes the following actions: • A route from an external BGP speaker is advertised to all clients and nonclient peers. • A route from a nonclient peer is advertised to all clients. • A route from a client is advertised to all clients and nonclient peers. Hence, the clients need not be fully meshed. Along with route reflector-aware BGP speakers, it is possible to have BGP speakers that do not understand the concept of route reflectors. They can be members of either client or nonclient groups, allowing an easy and gradual migration from the old BGP model to the route reflector model. Initially, you could create a single cluster with a route reflector and a few clients. All other iBGP speakers could be nonclient peers to the route reflector and then more clusters could be created gradually. An autonomous system can have multiple route reflectors. A route reflector treats other route reflectors just like other iBGP speakers. A route reflector can be configured to have other route reflectors in a client group or nonclient group. In a simple configuration, the backbone could be divided into many clusters. Each route reflector would be configured with other route reflectors as nonclient peers (thus, all route reflectors are fully meshed). The clients are configured to maintain iBGP sessions with only the route reflector in their cluster. Usually, a cluster of clients has a single route reflector. In that case, the cluster is identified by the router ID of the route reflector. To increase redundancy and avoid a single point of failure, a cluster might have more than one route reflector. In this case, all route reflectors in the cluster must be configured with the Cisco IOS XR Routing Configuration Guide RC-26 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software cluster ID so that a route reflector can recognize updates from route reflectors in the same cluster. All route reflectors serving a cluster should be fully meshed and all of them should have identical sets of client and nonclient peers. By default, the clients of a route reflector are not required to be fully meshed and the routes from a client are reflected to other clients. However, if the clients are fully meshed, the route reflector need not reflect routes to clients. As the iBGP learned routes are reflected, routing information may loop. The route reflector model has the following mechanisms to avoid routing loops: • Originator ID is an optional, nontransitive BGP attribute. It is a 4-byte attributed created by a route reflector. The attribute carries the router ID of the originator of the route in the local autonomous system. Therefore, if a misconfiguration causes routing information to come back to the originator, the information is ignored. • Cluster-list is an optional, nontransitive BGP attribute. It is a sequence of cluster IDs that the route has passed. When a route reflector reflects a route from its clients to nonclient peers, and vice versa, it appends the local cluster ID to the cluster-list. If the cluster-list is empty, a new cluster-list is created. Using this attribute, a route reflector can identify if routing information is looped back to the same cluster due to misconfiguration. If the local cluster ID is found in the cluster-list, the advertisement is ignored. Default Address Family for show Commands Most of the show commands require the address family (afi) and subsequent address family (safi) to be specified as arguments. The Cisco IOS XR software parser provides the ability to set the afi and safi so it is not necessary to specify them while executing a show command. The parser commands are: • set default-afi {ipv4 | ipv6 | all} • set default-safi {unicast | multicast | all} The parser automatically sets the default afi value to ipv4 and default safi value to unicast. It is necessary to use only the parser commands to change the default afi value from ipv4 or default safi value from unicast. Any afi or safi keyword specified in a show command overrides the values set using the parser commands. Use the following command to check the currently set value of the afi and safi: • show default-afi-safi How to Implement BGP on Cisco IOS XR Software This section contains instructions for the following tasks: • Enabling BGP Routing, page RC-28 (required) • Configuring a Routing Domain Confederation for BGP, page RC-31 (optional) • Resetting eBGP Session Immediately Upon Link Failure, page RC-33 (optional) • Logging Neighbor Changes, page RC-34 (optional) • Adjusting BGP Timers, page RC-34 (optional) • Changing the BGP Default Local Preference Value, page RC-35 (optional) • Configuring the MED Metric for BGP, page RC-36 (optional) • Configuring BGP Weights, page RC-38 (optional) Cisco IOS XR Routing Configuration Guide RC-27 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software • Tuning the BGP Best Path Calculation, page RC-39 (optional) • Indicating BGP Backdoor Routes, page RC-41 (optional) • Configuring Aggregate Addresses, page RC-43 (optional) • Redistributing iBGP Routes into IGP, page RC-44 (optional) • Redistributing Prefixes into Multiprotocol BGP, page RC-46 (optional) • Configuring BGP Route Dampening, page RC-48 (optional) • Applying Policy When Updating the Routing Table, page RC-52 (optional) • Setting BGP Administrative Distance, page RC-53 (optional) • Configuring a BGP Neighbor Group, page RC-55 (optional) • Configuring a BGP Neighbor, page RC-58 (required) • Configuring a Route Reflector for BGP, page RC-60 (optional) • Configuring BGP Route Filtering by Route Policy, page RC-62 (optional) • Disabling Next Hop Processing on BGP Updates, page RC-64 (optional) • Configuring BGP Community and Extended-Community Filtering, page RC-65 (optional) • Configuring Software to Store Updates from a Neighbor, page RC-67 (optional) • Disabling a BGP Neighbor, page RC-69 (optional) • Resetting Neighbors Using BGP Dynamic Inbound Soft Reset, page RC-71 (optional) • Resetting Neighbors Using BGP Outbound Soft Reset, page RC-71 (optional) • Resetting Neighbors Using BGP Hard Reset, page RC-72 (optional) • Clearing Caches, Tables and Databases, page RC-73 (optional) • Displaying System and Network Statistics, page RC-73 (optional) • Monitoring BGP Update Groups, page RC-75 (optional) Enabling BGP Routing Perform this task to enable BGP routing and establish a BGP routing process. Configuring BGP neighbors is included as part of enabling BGP routing. Note At least one neighbor and at least one address family must be configured to enable BGP routing. At least one neighbor with both a remote AS and an address family must be configured globally using the address family and remote as commands. Prerequisites BGP must be able to obtain a router identifier (for example, a configured loopback address). At least, one address family must be configured in the BGP router configuration and the same address family must also be configured under the neighbor. Cisco IOS XR Routing Configuration Guide RC-28 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Restrictions If the neighbor is configured as an external BGP (eBGP) peer, you must configure an inbound and outbound route policy on the neighbor using the route-policy command. SUMMARY STEPS 1. configure 2. route-policy name 3. end-policy 4. end or commit 5. configure 6. router bgp autonomous-system-number 7. bgp router-id {ip-address | interface-type interface-instance} 8. neighbor ip-address 9. remote-as autonomous-system-number 10. address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} 11. route-policy route-policy-name {in | out} 12. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 route-policy name (Optional) Defines a route policy named drop-as-1234 and enters route policy configuration mode. Example: RP/0/RP0/CPU0:router(config)# route-policy drop-as-1234 RP/0/RP0/CPU0:router(config-rpl)# if as-path passes-through '1234' then RP/0/RP0/CPU0:router(config-rpl)# apply check-communities RP/0/RP0/CPU0:router(config-rpl)# else RP/0/RP0/CPU0:router(config-rpl)# pass RP/0/RP0/CPU0:router(config-rpl)# endif Cisco IOS XR Routing Configuration Guide RC-29 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 3 Command or Action Purpose end-policy (Optional) Ends the definition of a route policy and exits route policy configuration mode. Example: RP/0/RP0/CPU0:router(config-rpl)# end-policy Step 4 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Step 5 configure Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 6 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 7 bgp router-id {ip-address | interface-type interface-instance} Configures the local router with a router id of 192.168.70.24. Example: RP/0/RP0/CPU0:router(config-bgp)# bgp router-id 192.168.70.24 Step 8 neighbor ip-address Example: RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.168.40.24 Cisco IOS XR Routing Configuration Guide RC-30 Places the router in neighbor configuration mode for BGP routing and configures the neighbor IP address 172.168.40.24 as a BGP peer. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 9 Command or Action Purpose remote-as autonomous-system-number Creates a neighbor and assigns it a remote autonomous system number of 2002. Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 2002 Step 10 address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} Enters global address family configuration mode for the IPv4 address family. Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicast Step 11 route-policy route-policy-name {in | out} (Optional) Applies the In-Ipv4 policy to inbound IPv4 unicast routes. Example: RP/0/RP0/CPU0:router(config-bgp-nbr-af)# route-policy In-Ipv4 in Step 12 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-nbr-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-nbr-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Configuring a Routing Domain Confederation for BGP Perform this task to configure the routing domain confederation for BGP. This includes specifying a confederation identifier and autonomous systems that belong to the confederation. Configuring a routing domain confederation reduces the internal BGP (iBGP) mesh by dividing an autonomous system into multiple autonomous systems and grouping them into a single confederation. Each autonomous system is fully meshed within itself and has a few connections to another autonomous system in the same confederation. The confederation maintains the next hop and local preference information, and that allows you to retain a single Interior Gateway Protocol (IGP) for all autonomous systems. To the outside world, the confederation looks like a single autonomous system. Cisco IOS XR Routing Configuration Guide RC-31 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. bgp confederation identifier autonomous-system-number 4. bgp confederation peers autonomous-system-number 5. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 bgp confederation identifier autonomous-system-number Example: RP/0/RP0/CPU0:router(config-bgp)# bgp confederation identifier 5 Cisco IOS XR Routing Configuration Guide RC-32 Specifies a BGP confederation identifier of 5. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 4 Command or Action Purpose bgp confederation peers autonomous-system-number Specifies that the BGP autonomous systems 1091, 1092, 1093, 1094, 1095, and 1096 belong to BGP confederation identifier 5. Example: RP/0/RP0/CPU0:router(config-bgp)# confederation peers 1091 RP/0/RP0/CPU0:router(config-bgp)# confederation peers 1092 RP/0/RP0/CPU0:router(config-bgp)# confederation peers 1093 RP/0/RP0/CPU0:router(config-bgp)# confederation peers 1094 RP/0/RP0/CPU0:router(config-bgp)# confederation peers 1095 RP/0/RP0/CPU0:router(config-bgp)# confederation peers 1096 Step 5 bgp bgp bgp bgp bgp bgp Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Resetting eBGP Session Immediately Upon Link Failure Immediately resetting BGP sessions of any directly adjacent external peers if the link used to reach them goes down is enabled by default. Use the bgp fast-external-fallover disable command to disable automatic resetting. The bgp fast-external-fallover disable command can also be used to turn the automatic reset back on. Cisco IOS XR Routing Configuration Guide RC-33 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Logging Neighbor Changes Logging neighbor changes is enabled by default. Use the log neighbor changes disable command to turn off logging. The log neighbor changes disable command can also be used to turn logging back on if it has been disabled. Adjusting BGP Timers Perform this task to set the timers for BGP neighbors. BGP uses certain timers to control periodic activities, such as the sending of keepalive messages and the interval after which a neighbor is assumed to be down if no messages are received from the neighbor during the interval. The values set using the timers bgp command can be overridden on particular neighbors using the timers command in the neighbor configuration mode. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. timers bgp keepalive hold-time 4. neighbor ip-address 5. timers keepalive hold-time 6. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 timers bgp keepalive hold-time Example: RP/0/RP0/CPU0:router(config-bgp)# timers bgp 30 90 Cisco IOS XR Routing Configuration Guide RC-34 Sets a default keepalive time of 30 seconds and a default hold time of 90 seconds for all neighbors. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 4 Command or Action Purpose neighbor ip-address Places the router in neighbor configuration mode for BGP routing and configures the neighbor IP address 172.168.40.24 as a BGP peer. Example: RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.168.40.24 Step 5 timers keepalive hold-time Example: (Optional) Sets the keepalive timer to 60 seconds and the hold-time timer to 220 seconds for BGP neighbor 172.168.40.24. RP/0/RP0/CPU0:router(config-bgp-nbr)# timers 60 220 Step 6 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-nbr)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-nbr)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Changing the BGP Default Local Preference Value Perform this task to set the default local preference value for BGP paths. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. bgp default local-preference value 4. end or commit Cisco IOS XR Routing Configuration Guide RC-35 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 bgp default local-preference value Sets the default local preference value from the default of 100 to 200, making it a more preferable path. Example: RP/0/RP0/CPU0:router(config-bgp)# bgp default local-preference 200 Step 4 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Configuring the MED Metric for BGP Perform this task to set the multi exit discriminator (MED) to advertise to peers for routes that do not already have a metric set (routes that were received with no MED attribute). SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. default-metric value Cisco IOS XR Routing Configuration Guide RC-36 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software 4. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 default-metric value Example: RP/0/RP0/CPU0:router(config-bgp)# default metric 10 Step 4 end or Sets the default metric to 10, which is used to set the MED to advertise to peers for routes that do not already have a metric set (routes that were received with no MED attribute). Saves configuration changes. commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Cisco IOS XR Routing Configuration Guide RC-37 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Configuring BGP Weights Perform this task to assign a weight to routes received from a neighbor. A weight is a number that you can assign to a path so that you can control the best path selection process. If you have particular neighbors that you want to prefer for most of your traffic, you can use the weight command to assign a higher weight to all routes learned from that neighbor. Restrictions The clear bgp command must be used for the newly configured weight to take effect. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. neighbor ip-address 4. remote-as autonomous-system-number 5. address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} 6. weight weight-value 7. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 neighbor ip-address Example: Places the router in neighbor configuration mode for BGP routing and configures the neighbor IP address 172.168.40.24 as a BGP peer. RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.168.40.24 Step 4 remote-as autonomous-system-number Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 2002 Cisco IOS XR Routing Configuration Guide RC-38 Creates a neighbor and assigns it a remote autonomous system number of 2002. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 5 Command or Action Purpose address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} Enters neighbor address family configuration mode for the IPv4 address family. Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicast Step 6 weight weight-value Assigns a weight of 41150 to all IPv4 unicast routes learned through 172.168.40.24. Example: RP/0/RP0/CPU0:router(config-bgp-nbr-af)# weight 41150 Step 7 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-nbr-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-nbr-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Tuning the BGP Best Path Calculation Perform this task to change the default BGP best path calculation behavior. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. bgp bestpath med missing-as-worst 4. bgp bestpath med always 5. bgp bestpath med confed 6. bgp bestpath as-path ignore 7. bgp bestpath compare-routerid Cisco IOS XR Routing Configuration Guide RC-39 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software 8. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 bgp bestpath med missing-as-worst Example: Directs the BGP software to consider a missing MED attribute in a path as having a value of infinity, making this path the least desirable path. RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath med missing-as-worst Step 4 bgp bestpath med always Example: Configures the BGP speaker in autonomous system 120 to compare MEDs among alternative paths, regardless of the autonomous system from which the paths are received. RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath med always Step 5 bgp bestpath med confed Enables BGP software to compare MED values for paths learned from confederation peers. Example: RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath med confed Step 6 bgp bestpath as-path ignore Example: RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath as-path ignore Cisco IOS XR Routing Configuration Guide RC-40 Configures the BGP software to ignore the autonomous system length when performing best path selection. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 7 Command or Action Purpose bgp bestpath compare-routerid Configure the BGP speaker in autonomous system 120 to compare the router IDs of similar paths. Example: RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath compare-routerid Step 8 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Indicating BGP Backdoor Routes Perform this task to set the administrative distance on an external Border Gateway Protocol (eBGP) route to that of a locally sourced BGP route, causing it to be less preferred than an Interior Gateway Protocol (IGP) route. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} 4. network {ip-address /prefix-length | ip-address mask} backdoor 5. end or commit Cisco IOS XR Routing Configuration Guide RC-41 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} Enters global address family configuration mode for the IPv4 address family. Example: RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicast Step 4 network {ip-address /prefix-length | ip-address mask} backdoor Configures the local router to originate and advertise the IPv4 unicast network 172.20.0.0/16. Example: RP/0/RP0/CPU0:router(config-bgp-af)# network 172.20.0.0/16 Step 5 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Cisco IOS XR Routing Configuration Guide RC-42 Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Configuring Aggregate Addresses Perform this task to create aggregate entries in a BGP routing table. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} 4. aggregate-address address/mask-length [as-set] [as-confed-set] [summary-only] [route-policy route-policy-name] 5. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} Enters global address family configuration mode for the IPv4 address family. Example: RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicast Cisco IOS XR Routing Configuration Guide RC-43 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 4 Command or Action Purpose aggregate-address address/mask-length [as-set] [as-confed-set] [summary-only] [route-policy route-policy-name] Creates an aggregate address. The path advertised for this route is an autonomous system set consisting of all elements contained in all paths that are being summarized. Example: • The as-set keyword generates autonomous system set path information and community information from contributing paths. • The as-confed-set keyword generates autonomous system confederation set path information from contributing paths. • The summary-only keyword filters all more specific routes from updates. • The route-policy route-policy-name keyword and argument specify the route policy used to set the attributes of the aggregate route. RP/0/RP0/CPU0:router(config-bgp-af)# aggregate-address 10.0.0.0/8 as-set Step 5 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Redistributing iBGP Routes into IGP Perform this task to redistribute iBGP routes into an Interior Gateway Protocol (IGP), such as Intermediate System-to-Intermediate System (IS-IS) or Open Shortest Path First (OSPF). Note Caution Use of the bgp redistribute-internal command requires the clear route * command to be issued to reinstall all BGP routes into the IP routing table. Redistributing iBGP routes into IGPs may cause routing loops to form within an autonomous system. Use this command with caution. Cisco IOS XR Routing Configuration Guide RC-44 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. bgp redistribute-internal 4. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 bgp redistribute-internal Allows the redistribution of iBGP routes into an IGP, such as IS-IS or OSPF. Example: RP/0/RP0/CPU0:router(config-bgp)# bgp redistribute-internal Step 4 end or Saves configuration changes. commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Cisco IOS XR Routing Configuration Guide RC-45 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Redistributing Prefixes into Multiprotocol BGP Perform this task to redistribute prefixes from another protocol into multiprotocol BGP. Redistribution is the process of injecting prefixes from one routing protocol into another routing protocol. This task shows how to inject prefixes from another routing protocol into multiprotocol BGP. Specifically, prefixes that are redistributed into multiprotocol BGP using the redistribute command are injected into the unicast database, the multicast database, or both. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} 4. redistribute connected [metric metric-value] [route-policy route-policy-name] or redistribute isis process-id [level {1 | 1-inter-area | 2}] [metric metric-value] [route-policy route-policy-name] or redistribute ospf process-id [match {external [1 | 2] | internal | nssa-external [1 | 2]]} [metric metric-value] [route-policy route-policy-name] or redistribute ospfv3 process-id [match {external [1 | 2] | internal | nssa-external [1 | 2]]} [metric metric-value] [route-policy route-policy-name] or redistribute static [metric metric-value] [route-policy route-policy-name] 5. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} Example: RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicast Cisco IOS XR Routing Configuration Guide RC-46 Enters global address family configuration mode for the IPv4 address family. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 4 Command or Action Purpose redistribute connected [metric metric-value] [route-policy route-policy-name] Causes IPv4 unicast OSPF routes from OSPF instance 110 to be redistributed into BGP. or redistribute isis process-id [level {1 | 1-inter-area | 2}] [metric metric-value] [route-policy route-policy-name] or redistribute ospf process-id [match {external [1 | 2] | internal | nssa-external [1 | 2]]} [metric metric-value] [route-policy route-policy-name] or redistribute ospfv3 process-id [match {external [1 | 2] | internal | nssa-external [1 | 2]]} [metric metric-value] [route-policy route-policy-name] or redistribute static [metric metric-value] [route-policy route-policy-name] Example: RP/0/RP0/CPU0:router(config-bgp-af)# redistribute ospf 110 Step 5 end or Saves configuration changes. commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Cisco IOS XR Routing Configuration Guide RC-47 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Configuring BGP Route Dampening Perform this task to configure and monitor BGP route dampening. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} 4. bgp dampening [half-life [reuse suppress max-suppress-time] | route-policy route-policy-name] 5. end or commit 6. show bgp [ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}] flap-statistics 7. show bgp [ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}] flap-statistics regexp regular-expression 8. show bgp [ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}] flap-statistics route-policy route-policy-name 9. show bgp [ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}] flap-statistics {ip-address [{mask | /prefix-length} 10. show bgp [ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}] flap-statistics {ip-address [{mask | /prefix-length} [longer-prefixes]] 11. clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} flap-statistics 12. clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} flap-statistics regexp regular-expression 13. clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} flap-statistics route-policy route-policy-name 14. clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} flap-statistics network/mask-length 15. clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} flap-statistics ip-address 16. show bgp [ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}] dampened-paths 17. clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} dampening [ip-address/mask-length] Cisco IOS XR Routing Configuration Guide RC-48 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} Enters global address family configuration mode for the IPv4 address family. Example: RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicast Step 4 bgp dampening [half-life [reuse suppress max-suppress-time] | route-policy route-policy-name] Configures BGP dampening for the IPv4 address family. The half-life argument is set to 30, the reuse argument is set to 1500, the suppress argument is set to 10000, and the max-suppress-time argument is set to 120. Example: RP/0/RP0/CPU0:router(config-bgp-af)# bgp dampening 30 1500 10000 120 Step 5 end or Saves configuration changes. commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Cisco IOS XR Routing Configuration Guide RC-49 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 6 Command or Action Purpose show bgp [ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}] flap-statistics Displays BGP flap statistics for all paths. Example: RP/0/RP0/CPU0:router# show bgp flap statistics Step 7 show bgp [ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}] flap-statistics regexp regular-expression Displays BGP flap statistics for all paths that match the regular expression _1$. Example: RP/0/RP0/CPU0:router# show bgp flap-statistics regexp _1$ Step 8 show bgp [ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}] flap-statistics route-policy route-policy-name Displays BGP flap statistics for route policy policy_A. Example: RP/0/RP0/CPU0:router(config)# show bgp flap-statistics route-policy policy_A Step 9 show bgp [ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}] flap-statistics {ip-address [{mask | /prefix-length} Displays BGP flap statistics for neighbor 172.20.1.1. Example: RP/0/RP0/CPU0:router# show bgp flap-statistics 172.20.1.1 Step 10 show bgp [ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}] flap-statistics {ip-address [{mask | /prefix-length} [longer-prefixes] Displays BGP flap statistics for more specific entries for neighbor 172.20.1.1. Example: RP/0/RP0/CPU0:router# show bgp flap-statistics 172.20.1.1 longer-prefixes Step 11 clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} flap-statistics Example: RP/0/RP0/CPU0:router# clear bgp all all flap-statistics Cisco IOS XR Routing Configuration Guide RC-50 Clears BGP flap statistics for all routes. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 12 Command or Action Purpose clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} flap-statistics regexp regular-expression Clears BGP flap statistics for all paths that match the regular expression _1$. Example: RP/0/RP0/CPU0:router# clear bgp ipv4 unicast flap-statistics _1$ Step 13 clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} flap-statistics route-policy route-policy-nane Clears BGP flap statistics for route policy policy_A. Example: RP/0/RP0/CPU0:router# clear bgp ipv4 unicast flap-statistics route-policy policy_A Step 14 clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} flap-statistics network/mask-length Clears BGP flap statistics for network 192.168.40.0/24. Example: RP/0/RP0/CPU0:router# clear bgp ipv4 unicast flap-statistics 192.168.40.0/24 Step 15 clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} flap-statistics ip-address Clears BGP flap statistics for routes received from this neighbor 172.20.1.1. Example: RP/0/RP0/CPU0:router# clear bgp ipv4 unicast flap-statistics 172.20.1.1 Step 16 show bgp [ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}] dampened-paths Displays the dampened routes, including the time remaining before they are unsuppressed. Example: RP/0/RP0/CPU0:router# show bgp dampened paths Step 17 clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} dampening [ip-address/mask-length] Clears route dampening information and unsuppresses the suppressed routes. Example: RP/0/RP0/CPU0:router# clear bgp dampening Cisco IOS XR Routing Configuration Guide RC-51 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Applying Policy When Updating the Routing Table Perform this task to apply a routing policy to routes being installed into the routing table. Prerequisites See the Implementing Routing Policy on Cisco IOS XR Software module of the Cisco IOS XR Routing Configuration Guide for a list of the supported attributes and operations that are valid for table policy filtering. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} 4. table-policy policy-name 5. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} Example: RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicast Cisco IOS XR Routing Configuration Guide RC-52 Enters global address family configuration mode for the IPv4 address family. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 4 Command or Action Purpose table-policy policy-name Applies the tbl-plcy-A policy to IPv4 unicast routes being installed into the routing table. Example: RP/0/RP0/CPU0:router(config-bgp-af)# table-policy tbl-plcy-A Step 5 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Setting BGP Administrative Distance Perform this task to specify the use of administrative distances that can be used to prefer one class of route over another. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} 4. distance bgp external-distance internal-distance local-distance 5. end or commit Cisco IOS XR Routing Configuration Guide RC-53 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} Enters global address family configuration mode for the IPv4 address family. Example: RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicast Step 4 RP/0/RP0/CPU0:router(config-bgp-af)# distance bgp 20 20 200 Sets the external, internal, and local administrative distances to prefer one class of routes over another. The higher the value, the lower the trust rating. The external-distance argument is set to 20, the internal-distance argument is set to 20, and the local-distance argument is set to 200. end Saves configuration changes. distance bgp external-distance internal-distance local-distance Example: Step 5 or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Cisco IOS XR Routing Configuration Guide RC-54 Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Configuring a BGP Neighbor Group Perform this task to configure BGP neighbor groups and apply the neighbor group configuration to a neighbor. After a neighbor group is configured, each neighbor can inherit the configuration through the use command. If a neighbor is configured to use a neighbor group, the neighbor (by default) inherits the entire configuration of the neighbor group, which includes the address family-independent and address family-dependent configurations. The inherited configuration can be overridden if you directly configure commands for the neighbor or configure session groups or address family groups through the use command. From neighbor group configuration mode, you can configure address family-independent parameters for the neighbor group. Use the address-family command when in the neighbor group configuration mode. After specifying the neighbor group name using the neighbor group command, you can assign options to the neighbor group. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. neighbor-group name 4. remote-as autonomous-system-number 5. advertisement-interval seconds 6. description text 7. dmz-link-bandwidth 8. ebgp-multihop [ttl-value] 9. local-as autonomous-system-number 10. password {clear | encrypted} password 11. password-disable 12. receive-buffer-size socket-size [bgp-size] 13. send-buffer-size socket-size [bgp-size] 14. timers keepalive hold-time 15. ttl-security 16. update-source interface-type interface-number 17. exit 18. neighbor ip-address 19. use neighbor-group group-name 20. end or commit Cisco IOS XR Routing Configuration Guide RC-55 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 neighbor-group name Places the router in neighbor group configuration mode. Example: RP/0/RP0/CPU0:router(config-bgp)# neighbor-group nbr-grp-A Step 4 remote-as autonomous-system-number Creates a neighbor and assigns it a remote autonomous system number of 2002. Example: RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# remote-as 2002 Step 5 advertisement-interval seconds (Optional) Sets the minimum time between sending BGP routing updates to 10 seconds. Example: RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# advertisement-interval 10 Step 6 description text (Optional) Configures the description “Neighbor on BGP 120” for neighbor group nbr-grp-A. Example: RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# description Neighbor on BGP 120 Step 7 dmz-link-bandwidth (Optional) Advertises the bandwidth of links on router bgp 120. Example: RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# dmz-link-bandwidth Step 8 ebgp-multihop [ttl-value] (Optional) Allows a BGP connection to neighbor group nbr-grp-A. Example: RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# ebgp-multihop Step 9 local-as autonomous-system-number Example: RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# local-as 30 Cisco IOS XR Routing Configuration Guide RC-56 (Optional) Specifies that BGP use autonomous system 30 for the purpose of peering with neighbor group nbr-grp-A. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 10 Command or Action Purpose password {clear | encrypted} password (Optional) Configures neighbor group nbr-grp-A to use MD5 authentication with the password pswd123. Example: RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# password clear pswd123 Step 11 password-disable (Optional) Overrides any inherited password configuration from the neighbor group. Example: RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# password-disable Step 12 receive-buffer-size socket-size [bgp-size] Example: (Optional) Sets the receive buffer sizes for neighbor group nbr-grp-A to 45215 bytes for the socket buffer and 5156 bytes for the BGP buffer. RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# receive-buffer-size 45215 5156 Step 13 send-buffer-size socket-size [bgp-size] Example: (Optional) Sets the send buffer sizes for neighbor group nbr-grp-A to 8741 bytes for the socket buffer and 8741 bytes for the BGP buffer. RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# send-buffer-size 8741 8741 Step 14 timers keepalive hold-time Example: (Optional) Sets the keepalive timer to 60 seconds and the hold-time timer to 220 seconds for the BGP neighbor group nbr-grp-A. RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# timers 60 220 Step 15 ttl-security (Optional) Enables TTL security for eBGP neighbor group nbr-grp-A. Example: RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# ttl-security Step 16 update-source interface-type interface-number Example: (Optional) Configures the router to use the IP address from the Loopback0 interface when trying to open a session with neighbor group nbr-grp-A. RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# update-source Loopback0 Step 17 exit Exits the current configuration mode. Example: RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# exit Step 18 neighbor ip-address Example: Places the router in neighbor configuration mode for BGP routing and configures the neighbor IP address 172.168.40.24 as a BGP peer. RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.168.40.24 Cisco IOS XR Routing Configuration Guide RC-57 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 19 Command or Action Purpose use neighbor-group group-name (Optional) Specifies that BGP neighbor 172.168.40.24 inherit configuration from neighbor group nbr-grp-A. Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# use neighbor-group nbr-grp-A Step 20 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-nbr)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-nbr)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Configuring a BGP Neighbor Perform this task to configure BGP neighbors. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. neighbor ip-address 4. remote-as autonomous-system-number 5. address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} 6. end or commit Cisco IOS XR Routing Configuration Guide RC-58 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 neighbor ip-address Example: Places the router in neighbor configuration mode for BGP routing and configures the neighbor IP address 172.168.40.24 as a BGP peer. RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.168.40.24 Step 4 remote-as autonomous-system-number Creates a neighbor and assigns it a remote autonomous system number of 2002. Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 2002 Step 5 address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} Enters neighbor address family configuration mode for the IPv4 address family. Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicast Step 6 end or Saves configuration changes. commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-nbr-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-nbr-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Cisco IOS XR Routing Configuration Guide RC-59 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Configuring a Route Reflector for BGP Perform this task to configure a route reflector for BGP. All the neighbors configured with the route-reflector-client command are members of the client group, and the remaining iBGP peers are members of the nonclient group for the local route reflector. Together, a route reflector and its clients form a cluster. A cluster of clients usually has a single route reflector. In such instances, the cluster is identified by the software as the router ID of the route reflector. To increase redundancy and avoid a single point of failure in the network, a cluster can have more than one route reflector. If it does, all route reflectors in the cluster must be configured with the same 4-byte cluster ID so that a route reflector can recognize updates from route reflectors in the same cluster. The bgp cluster-id command is used to configure the cluster ID when the cluster has more than one route reflector. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. bgp cluster-id cluster-id 4. neighbor ip-address 5. remote-as autonomous-system-number 6. address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} 7. route-reflector-client 8. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 bgp cluster-id cluster-id Example: RP/0/RP0/CPU0:router(config-bgp)# bgp cluster-id 192.168.70.1 Cisco IOS XR Routing Configuration Guide RC-60 Configures the local router as one of the route reflectors serving the cluster. It is configured with the cluster ID of 192.168.70.1 to identify the cluster. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 4 Command or Action Purpose neighbor ip-address Places the router in neighbor configuration mode for BGP routing and configures the neighbor IP address 172.168.40.24 as a BGP peer. Example: RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.168.40.24 Step 5 remote-as autonomous-system-number Creates a neighbor and assigns it a remote autonomous system number of 2002. Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 2002 Step 6 address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} Enters neighbor address family configuration mode for the IPv4 address family. Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicast Step 7 route-reflector-client Configures the router as a BGP route reflector and configures the neighbor 172.168.40.24 as its client. Example: RP/0/RP0/CPU0:router(config-bgp-nbr-af)# route-reflector-client Step 8 end or Saves configuration changes. commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-nbr-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-nbr-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Cisco IOS XR Routing Configuration Guide RC-61 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Configuring BGP Route Filtering by Route Policy Perform this task to configure BGP routing filtering by route policy. Prerequisites See the Implementing Routing Policy on Cisco IOS XR Software module of the Cisco IOS XR Routing Configuration Guide for a list of the supported attributes and operations that are valid for inbound and outbound neighbor policy filtering. SUMMARY STEPS 1. configure 2. route-policy name 3. end-policy 4. router bgp autonomous-system-number 5. neighbor ip-address 6. address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} 7. route-policy route-policy-name {in | out} 8. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 route-policy name (Optional) Defines a route policy named drop-as-1234 and enters route policy configuration mode. Example: RP/0/RP0/CPU0:router(config)# route-policy drop-as-1234 RP/0/RP0/CPU0:router(config-rpl)# if as-path passes-through '1234' then RP/0/RP0/CPU0:router(config-rpl)# apply check-communities RP/0/RP0/CPU0:router(config-rpl)# else RP/0/RP0/CPU0:router(config-rpl)# pass RP/0/RP0/CPU0:router(config-rpl)# endif Step 3 end-policy Example: RP/0/RP0/CPU0:router(config-rpl)# end-policy Cisco IOS XR Routing Configuration Guide RC-62 (Optional) Ends the definition of a route policy and exits route policy configuration mode. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 4 Command or Action Purpose router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 5 neighbor ip-address Example: Places the router in neighbor configuration mode for BGP routing and configures the neighbor IP address 172.168.40.24 as a BGP peer. RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.168.40.24 Step 6 address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} Enters neighbor address family configuration mode for the IPv4 address family. Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicast Step 7 route-policy route-policy-name {in | out} Applies the In-Ipv4 policy to inbound IPv4 unicast routes. Example: RP/0/RP0/CPU0:router(config-bgp-nbr-af)# route-policy In-Ipv4 in Step 8 end or Saves configuration changes. commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-nbr-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-nbr-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Cisco IOS XR Routing Configuration Guide RC-63 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Disabling Next Hop Processing on BGP Updates Perform this task to disable next hop calculation for a neighbor and insert your own address in the next hop field of BGP updates. Disabling the calculation of the best next hop to use when advertising a route causes all routes to be advertised with the network device as the next hop. Note Next hop processing can be disabled for address family group, neighbor group, or neighbor address family. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. neighbor ip-address 4. remote-as autonomous-system-number 5. address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} 6. next-hop-self 7. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 neighbor ip-address Example: Places the router in neighbor configuration mode for BGP routing and configures the neighbor IP address 172.168.40.24 as a BGP peer. RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.168.40.24 Step 4 remote-as autonomous-system-number Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 2002 Cisco IOS XR Routing Configuration Guide RC-64 Creates a neighbor and assigns it a remote autonomous system number of 2002. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 5 Command or Action Purpose address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} Enters neighbor address family configuration mode for the IPv4 address family. Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicast Step 6 RP/0/RP0/CPU0:router(config-bgp-nbr-af)# next-hop-self Sets the next hop attribute for all IPv4 unicast routes advertised to neighbor 172.168.40.24 to the address of the local router. Disabling the calculation of the best next hop to use when advertising a route causes all routes to be advertised with the local network device as the next hop. end Saves configuration changes. next-hop-self Example: Step 7 or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-nbr-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-nbr-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Configuring BGP Community and Extended-Community Filtering Perform this task to specify that community attributes should be sent to an eBGP neighbor. Perform this task to specify that community/extended-community attributes should be sent to an eBGP neighbor. These attributes are not sent to an eBGP neighbor by default. By contrast, they are always sent to iBGP neighbors. This section provides examples on how to enable sending community attributes. The send-community-ebgp keyword can be replaced by the send-extended-community-ebgp keyword to enable sending extended-communities. Note If the send-community-ebgp command is configured for a neighbor group or address family group, all neighbors using the group inherit the configuration. Configuring the command specifically for a neighbor overrides inherited values. Cisco IOS XR Routing Configuration Guide RC-65 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. neighbor ip-address 4. remote-as autonomous-system-number 5. address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} 6. send-community-ebgp 7. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 neighbor ip-address Example: Places the router in neighbor configuration mode for BGP routing and configures the neighbor IP address 172.168.40.24 as a BGP peer. RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.168.40.24 Step 4 remote-as autonomous-system-number Creates a neighbor and assigns it a remote autonomous system number of 2002. Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 2002 Step 5 address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicast Cisco IOS XR Routing Configuration Guide RC-66 Enters neighbor address family configuration mode for the IPv4 address family. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 6 Command or Action Purpose send-community-ebgp Specifies that the router send community attributes (which are disabled by default for eBGP neighbors) to eBGP neighbor 172.168.40.24 for IPv4 multicast routes. Example: RP/0/RP0/CPU0:router(config-bgp-nbr-af)# send-community-ebgp Step 7 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-nbr-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-nbr-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Configuring Software to Store Updates from a Neighbor Perform this task to configure the software to store updates received from a neighbor. The soft-reconfiguration inbound command causes a route refresh request to be sent to the neighbor if the neighbor is route refresh capable. If the neighbor is not route refresh capable, the neighbor must be reset to relearn received routes using the clear bgp soft command. See the “Resetting Neighbors Using BGP Dynamic Inbound Soft Reset” section on page RC-71. Note Storing updates from a neighbor works only if either the neighbor is route refresh capable or if the soft-reconfiguration inbound command is configured. Even if the neighbor is route refresh capable and the soft-reconfiguration inbound command is configured, the original routes are not stored unless the always option is used with the command. The original routes can be easily retrieved with a route refresh request. Route refresh sends a request to the peer to resend its routing information. The soft-reconfiguration inbound command stores all paths received from the peer in an unmodified form and refers to these stored paths during the clear. Soft reconfiguration is memory intensive. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. neighbor ip-address Cisco IOS XR Routing Configuration Guide RC-67 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software 4. address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} 5. soft-reconfiguration inbound always 6. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 neighbor ip-address Example: Places the router in neighbor configuration mode for BGP routing and configures the neighbor IP address 172.168.40.24 as a BGP peer. RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.168.40.24 Step 4 address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast} Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicast Cisco IOS XR Routing Configuration Guide RC-68 Enters neighbor address family configuration mode for the IPv4 address family. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 5 Command or Action Purpose soft-reconfiguration inbound always Configures the software to store updates received from neighbor 172.168.40.24. Soft reconfiguration inbound causes the software to store the original unmodified route in addition to a route that is modified or filtered. This allows a “soft clear” to be performed after the inbound policy is changed. Example: RP/0/RP0/CPU0:router(config-bgp-nbr-af)# soft-reconfiguration inbound always Step 6 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-nbr-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-nbr-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Disabling a BGP Neighbor Perform this task to administratively shut down a neighbor without removing the configuration. SUMMARY STEPS 1. configure 2. router bgp autonomous-system-number 3. neighbor ip-address 4. shutdown 5. end or commit Cisco IOS XR Routing Configuration Guide RC-69 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp autonomous-system-number Enters BGP configuration mode allowing you to configure the BGP routing process. Example: RP/0/RP0/CPU0:router(config)# router bgp 120 Step 3 neighbor ip-address Example: Places the router in neighbor configuration mode for BGP routing and configures the neighbor IP address 172.168.40.24 as a BGP peer. RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.168.40.24 Step 4 shutdown Disables all active sessions for neighbor 172.168.40.24. Example: RP/0/RP0/CPU0:router(config-bgp-nbr)# shutdown Step 5 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-nbr)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-bgp-nbr)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Cisco IOS XR Routing Configuration Guide RC-70 Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Resetting Neighbors Using BGP Dynamic Inbound Soft Reset Perform this task to trigger an inbound soft reset of the specified address families for the specified group or neighbors. Resetting neighbors is useful if you change the inbound policy for the neighbors or any other configuration that affects the sending or receiving of routing updates. If an inbound soft reset is triggered, BGP sends a REFRESH request to the neighbor if the neighbor has advertised the ROUTE_REFRESH capability. To determine whether the neighbor has advertised the ROUTE_REFRESH capability, use the show bgp neighbors command. SUMMARY STEPS 1. show bgp neighbors 2. clear bgp {ipv4 | ipv6 | all} {unicast | multicast | all} {* | ip-address | as-number | external} soft in DETAILED STEPS Step 1 Command or Action Purpose show bgp neighbors Verifies that received route refresh capability from the neighbor is enabled. Example: RP/0/RP0/CPU0:router# show bgp neighbors Step 2 clear bgp {ipv4 | ipv6 | all} {unicast | multicast | all} {* | ip-address | as-number | external} soft in Soft resets a BGP neighbor. • The * keyword resets all BGP neighbors. • The ip-address argument specifies the address of the neighbor to be reset. • The as-number argument specifies that all neighbors that match the autonomous system number be reset. • The external keyword specifies that all external neighbors are reset. Example: RP/0/RP0/CPU0:router# clear bgp ipv4 unicast 10.0.0.1 soft in Resetting Neighbors Using BGP Outbound Soft Reset Perform this task to trigger an outbound soft reset of the specified address families for the specified group or neighbors. Resetting neighbors is useful if you change the outbound policy for the neighbors or any other configuration that affects the sending or receiving of routing updates. If an outbound soft reset is triggered, BGP resends all routes for the address family to the given neighbors. To determine whether the neighbor has advertised the ROUTE_REFRESH capability, use the show bgp neighbors command. Cisco IOS XR Routing Configuration Guide RC-71 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software SUMMARY STEPS 1. show bgp neighbors 2. clear bgp {ipv4 | ipv6 | all} {unicast | multicast | all} {* | ip-address | as-number | external} soft out DETAILED STEPS Step 1 Command or Action Purpose show bgp neighbors Verifies that received route refresh capability from the neighbor is enabled. Example: RP/0/RP0/CPU0:router# show bgp neighbors Step 2 clear bgp {ipv4 | ipv6 | all} {unicast | multicast | all} {* | ip-address | as-number | external} soft out Soft resets a BGP neighbor. • The * keyword resets all BGP neighbors. • The ip-address argument specifies the address of the neighbor to be reset. • The as-number argument specifies that all neighbors that match the autonomous system number be reset. • The external keyword specifies that all external neighbors are reset. Example: RP/0/RP0/CPU0:router# clear bgp ipv4 unicast 10.0.0.2 soft out Resetting Neighbors Using BGP Hard Reset Perform this task to reset neighbors using a hard reset. A hard reset removes the TCP connection to the neighbor, removes all routes received from the neighbor from the BGP table, and then re-establishes the session with the neighbor. If the graceful keyword is specified, the routes from the neighbor are not removed from the BGP table immediately, but are marked as stale. After the session is re-established, any stale route that has not been received again from the neighbor is removed. SUMMARY STEPS 1. clear bgp {* | ip-address | as-number | external} [graceful] DETAILED STEPS Step 1 Command or Action Purpose clear bgp {* | ip-address | as-number | external} [graceful] Clears a BGP neighbor. The graceful keyword specifies a graceful restart. Example: RP/0/RP0/CPU0:router# clear bgp 10.0.0.3 Cisco IOS XR Routing Configuration Guide RC-72 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Clearing Caches, Tables and Databases Perform this task to remove all contents of a particular cache, table, or database. Clearing a cache, table, or database can become necessary when the contents of the particular structure have become, or are suspected to be, invalid. SUMMARY STEPS 1. clear bgp ip-address 2. clear bgp external 3. clear bgp * DETAILED STEPS Step 1 Command or Action Purpose clear bgp ip-address Clears neighbor 172.20.1.1. Example: RP/0/RP0/CPU0:router# clear bgp 172.20.1.1 Step 2 clear bgp external Clears all external peers. Example: RP/0/RP0/CPU0:router# clear bgp external Step 3 Clears all BGP neighbors. clear bgp * Example: RP/0/RP0/CPU0:router# clear bgp * Displaying System and Network Statistics Perform this task to display specific statistics, such as the contents of BGP routing tables, caches, and databases. Information provided can be used to determine resource usage and solve network problems. You can also display information about node reachability and discover the routing path that the packets of your device are taking through the network. SUMMARY STEPS 1. show bgp cidr-only 2. show bgp count-only 3. show bgp community community-list [exact-match] 4. show bgp regexp regular-expression 5. show bgp 6. show bgp neighbors ip-address [advertised-routes | dampened-routes | flap-statistics | performance-statistics | received prefix-filter | routes] 7. show bgp paths Cisco IOS XR Routing Configuration Guide RC-73 Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software 8. show bgp neighbor-group group-name configuration 9. show bgp summary DETAILED STEPS Step 1 Command or Action Purpose show bgp cidr-only Displays routes with nonnatural network masks (classless interdomain routing [CIDR]) routes. Example: RP/0/RP0/CPU0:router# show bgp cidr-only Step 2 show bgp count-only Displays the number of paths. Example: RP/0/RP0/CPU0:router# show bgp count-only Step 3 show bgp community community-list [exact-match] Displays routes that match the BGP community 1081:5. Example: RP/0/RP0/CPU0:router# show bgp community 1081:5 exact-match Step 4 show bgp regexp regular-expression Displays routes that match the autonomous system path regular expression "^3 ". Example: RP/0/RP0/CPU0:router# show bgp regexp "^3 " Step 5 show bgp Displays entries in the BGP routing table. Example: RP/0/RP0/CPU0:router# show bgp Step 6 show bgp neighbors ip-address [advertised-routes | dampened-routes | flap-statistics | performance-statistics | received prefix-filter | routes] Example: RP/0/RP0/CPU0:router# show bgp neighbors 10.0.101.1 Cisco IOS XR Routing Configuration Guide RC-74 Displays information about the BGP connection to neighbor 10.0.101.1. • The advertised-routes keyword displays all routes the router advertised to the neighbor. • The dampened-routes keyword displays the dampened routes that are learned from the neighbor. • The flap-statistics keyword displays flap statistics of the routes learned from the neighbor. • The performance-statistics keyword displays performance statistics relating to work done by the BGP process for this neighbor. • The received prefix-filter keyword and argument display the received prefix list filter. • The routes keyword displays routes learned from the neighbor. Implementing BGP on Cisco IOS XR Software How to Implement BGP on Cisco IOS XR Software Step 7 Command or Action Purpose show bgp paths Displays all BGP paths in the database. Example: RP/0/RP0/CPU0:router# show bgp paths Step 8 show bgp neighbor-group group-name configuration Displays the effective configuration for neighbor group group_1, including any configuration inherited by this neighbor group. Example: RP/0/RP0/CPU0:router# show bgp neighbor-group group_1 configuration Step 9 show bgp summary Displays the status of all BGP connections. Example: RP/0/RP0/CPU0:router# show bgp summary Monitoring BGP Update Groups This task displays information related to the processing of BGP update groups. SUMMARY STEPS 1. show bgp [{ipv4 | ipv6 | all} {unicast | multicast | all]} update-group [neighbor ip-address | process-id.index [summary | performance-statistics]] DETAILED STEPS Step 1 Command or Action Purpose show bgp [{ipv4 | ipv6 | all} {unicast | multicast | all}] update-group [neighbor ip-address | process-id.index [summary | performance-statistics]] Displays information about BGP update groups. • The ip-address argument displays the update groups to which that neighbor belongs. • The process-id.index argument selects a particular update group to display and is specified as follows: process id (dot) index. Process ID range is from 0 to 254. Index range is from 0 to 4294967295. • The summary keyword displays summary information for neighbors in a particular update group. • If no argument is specified, this command displays information for all update groups (for the specified address family). • The performance-statistics keyword displays performance statistics for an update group. Example: RP/0/RP0/CPU0:router# show bgp update-group 0.0 Cisco IOS XR Routing Configuration Guide RC-75 Implementing BGP on Cisco IOS XR Software Configuration Examples for Implementing BGP on Cisco IOS XR Software Configuration Examples for Implementing BGP on Cisco IOS XR Software This section provides the following configuration examples: • Enabling BGP: Example, page RC-76 • Displaying BGP Update Groups: Example, page RC-77 • BGP Neighbor Configuration: Example, page RC-78 • BGP Confederation: Example, page RC-78 • BGP Route Reflector: Example, page RC-79 Enabling BGP: Example The following shows how to enable BGP. prefix-set static 2020::/64, 2012::/64, 10.10.0.0/16, 10.2.0.0/24 end-set route-policy pass-all pass end-policy route-policy set_next_hop_agg_v4 set next-hop 10.0.0.1 end-policy route-policy set_next_hop_static_v4 if (destination in static) then set next-hop 10.1.0.1 else drop endif end-policy route-policy set_next_hop_agg_v6 set next-hop 2003::121 end-policy route-policy set_next_hop_static_v6 if (destination in static) then set next-hop 2011::121 else drop endif end-policy router bgp 65000 bgp fast-external-fallover disable bgp confederation peers 65001 65002 bgp confederation identifier 1 bgp router-id 1.1.1.1 address-family ipv4 unicast aggregate-address 10.2.0.0/24 route-policy set_next_hop_agg_v4 aggregate-address 10.3.0.0/24 redistribute static route-policy set_next_hop_static_v4 Cisco IOS XR Routing Configuration Guide RC-76 Implementing BGP on Cisco IOS XR Software Configuration Examples for Implementing BGP on Cisco IOS XR Software address-family ipv4 multicast aggregate-address 10.2.0.0/24 route-policy set_next_hop_agg_v4 aggregate-address 10.3.0.0/24 redistribute static route-policy set_next_hop_static_v4 address-family ipv6 unicast aggregate-address 2012::/64 route-policy set_next_hop_agg_v6 aggregate-address 2013::/64 redistribute static route-policy set_next_hop_static_v6 address-family ipv6 multicast aggregate-address 2012::/64 route-policy set_next_hop_agg_v6 aggregate-address 2013::/64 redistribute static route-policy set_next_hop_static_v6 neighbor 10.0.101.60 remote-as 65000 address-family ipv4 unicast address-family ipv4 multicast neighbor 10.0.101.61 remote-as 65000 address-family ipv4 unicast address-family ipv4 multicast neighbor 10.0.101.62 remote-as 3 address-family ipv4 unicast route-policy pass-all in route-policy pass-all out address-family ipv4 multicast route-policy pass-all in route-policy pass-all out neighbor 10.0.101.64 remote-as 5 update-source Loopback0 address-family ipv4 unicast route-policy pass-all in route-policy pass-all out address-family ipv4 multicast route-policy pass-all in route-policy pass-all out Displaying BGP Update Groups: Example The following is sample output from the show bgp update-group command executed in EXEC mode: RP/0/RP0/CPU0:router# show bgp update-group Update group for IPv4 Unicast, index 0.1: Attributes: Outbound Route map:rm Minimum advertisement interval:30 Messages formatted:2, replicated:2 Neighbors in this update group: 10.0.101.92 Update group for IPv4 Unicast, index 0.2: Attributes: Minimum advertisement interval:30 Messages formatted:2, replicated:2 Neighbors in this update group: 10.0.101.91 Cisco IOS XR Routing Configuration Guide RC-77 Implementing BGP on Cisco IOS XR Software Configuration Examples for Implementing BGP on Cisco IOS XR Software BGP Neighbor Configuration: Example The following example shows how BGP neighbors on an autonomous system are configured to share information. In the example, a BGP router is assigned to autonomous system 109, and two networks are listed as originating in the autonomous system. Then the addresses of three remote routers (and their autonomous systems) are listed. The router being configured shares information about networks 131.108.0.0 and 192.31.7.0 with the neighbor routers. The first router listed is in a different autonomous system; the second neighbor and remote-as commands specify an internal neighbor (with the same autonomous system number) at address 131.108.234.2; and the third neighbor and remote-as commands specify a neighbor on a different autonomous system. router bgp 109 network 131.108.0.0 network 192.31.7.0 neighbor 131.108.200.1 remote-as 167 neighbor 131.108.234.2 remote-as 109 neighbor 150.136.64.19 remote-as 99 BGP Confederation: Example The following is a sample configuration that shows several peers in a confederation. The confederation consists of three internal autonomous systems with autonomous system numbers 6001, 6002, and 6003. To the BGP speakers outside the confederation, the confederation looks like a normal autonomous system with autonomous system number 666 (specified using the bgp confederation identifier command). In a BGP speaker in autonomous system 6001, the bgp confederation peers command marks the peers from autonomous systems 6002 and 6003 as special eBGP peers. Hence, peers 171.69.232.55 and 171.69.232.56 get the local preference, next hop, and MED unmodified in the updates. The router at 160.69.69.1 is a normal eBGP speaker and the updates received by it from this peer are just like a normal eBGP update from a peer in autonomous system 666. router bgp 6001 bgp confederation identifier 666 bgp confederation peers 6002 6003 neighbor 171.69.232.55 remote-as 6002 neighbor 171.69.232.56 remote-as 6003 neighbor 160.69.69.1 remote-as 777 In a BGP speaker in autonomous system 6002, the peers from autonomous systems 6001 and 6003 are configured as special eBGP peers. Peer 170.70.70.1 is a normal iBGP peer and peer 199.99.99.2 is a normal eBGP peer from autonomous system 700. router bgp 6002 bgp confederation identifier 666 bgp confederation peers 6001 6003 neighbor 170.70.70.1 remote-as 6002 neighbor 171.69.232.57 remote-as 6001 neighbor 171.69.232.56 remote-as 6003 Cisco IOS XR Routing Configuration Guide RC-78 Implementing BGP on Cisco IOS XR Software Where to Go Next neighbor 199.99.99.2 remote-as 700 In a BGP speaker in autonomous system 6003, the peers from autonomous systems 6001 and 6002 are configured as special eBGP peers. Peer 200.200.200.200 is a normal eBGP peer from autonomous system 701. router bgp 6003 bgp confederation identifier 666 bgp confederation peers 6001 6002 neighbor 171.69.232.57 remote-as 6001 neighbor 171.69.232.55 remote-as 6002 neighbor 200.200.200.200 remote-as 701 The following is a part of the configuration from the BGP speaker 200.200.200.205 from autonomous system 701 in the same example. Neighbor 171.69.232.56 is configured as a normal eBGP speaker from autonomous system 666. The internal division of the autonomous system into multiple autonomous systems is not known to the peers external to the confederation. router bgp 701 neighbor 171.69.232.56 remote-as 666 neighbor 200.200.200.205 remote-as 701 BGP Route Reflector: Example The following example shows how to use an address family to configure internal BGP peer 10.1.1.1 as a route reflector client for both unicast and multicast prefixes: router bgp 140 neighbor 10.1.1.1 remote-as 140 address-family ipv4 unicast route-reflector-client router bgp 140 neighbor 10.1.1.1 remote-as 140 address-family ipv4 multicast route-reflector-client Where to Go Next For detailed information about BGP commands, see the Cisco IOS XR Routing Command Reference document. Cisco IOS XR Routing Configuration Guide RC-79 Implementing BGP on Cisco IOS XR Software Additional References Additional References The following sections provide references related to implementing BGP for Cisco IOS XR software. Related Documents Related Topic Document Title BGP commands: complete command syntax, command Cisco IOS XR Routing Command Reference, Release 3.2 modes, command history, defaults, usage guidelines, and examples Standards Standards Title draft-ietf-idr-bgp4-26.txt A Border Gateway Protocol 4, by Y. Rekhter, T.Li, S. Hares draft-ietf-idr-bgp4-mib-15.txt Definitions of Managed Objects for the Fourth Version of Border Gateway Protocol (BGP-4), by J. Hass and S. Hares draft-ietf-idr-cease-subcode-05.txt Subcodes for BGP Cease Notification Message, by Enke Chen, V. Gillet MIBs MIBs MIBs Link • BGP4-MIB • CISCO-BGP4-MIB To locate and download MIBs for selected platforms using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL: http://cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml RFCs RFCs Title RFC 1997 BGP Communities Attribute RFC 2385 Protection of BGP Sessions via the TCP MD5 Signature Option RFC 2439 BGP Route Flap Damping RFC 2545 Use of BGP-4 Multiprotocol Extensions for IPv6 Inter-Domain Routing RFC 2796 BGP Route Reflection - An Alternative to Full Mesh IBGP RFC 2858 Multiprotocol Extensions for BGP-4 RFC 2918 Route Refresh Capability for BGP-4 Cisco IOS XR Routing Configuration Guide RC-80 Implementing BGP on Cisco IOS XR Software Additional References RFCs Title RFC 3065 Autonomous System Confederations for BGP RFC 3392 Capabilities Advertisement with BGP-4 Technical Assistance Description Link http://www.cisco.com/techsupport The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content. Cisco IOS XR Routing Configuration Guide RC-81 Implementing BGP on Cisco IOS XR Software Additional References Cisco IOS XR Routing Configuration Guide RC-82 Implementing IS-IS on Cisco IOS XR Software Integrated Intermediate System-to-Intermediate System (IS-IS), Internet Protocol Version 4 (IPv4), is a standards-based Interior Gateway Protocol (IGP). Cisco IOS XR implements the IP routing capabilities described in International Organization for Standardization (ISO)/International Engineering Consortium (IEC) 10589 and RFC 1995, and adds the standard extensions for single topology and multitopology IS-IS for IP Version 6 (IPv6). This module describes the new and revised tasks you need to implement IS-IS (IPv4 and IPv6) on your Cisco IOS XR network. Note For more information about IS-IS on the Cisco IOS XR software and complete descriptions of the IS-IS commands listed in this module, you can refer to the “Related Documents” section of this module. To locate documentation for other commands that might appear while of executing a configuration task, search online in the Cisco IOS XR software master command index. Feature History for Implementing IS-IS on Cisco IOS XR Software Release Modification Release 2.0 This feature was introduced on the Cisco CRS-1. Release 3.0 No modification. Release 3.2 Support was added for the Cisco XR 12000 Series Router. The ability to configure a broadcast medium connecting two networking devices as a point-to-point link was added. Release 3.2.2 Support was added for the multicast-intact feature. Contents • Prerequisites for Implementing IS-IS on Cisco IOS XR Software, page RC-84 • Restrictions for Implementing IS-IS on Cisco IOS XR Software, page RC-84 • Information About Implementing IS-IS on Cisco IOS XR Software, page RC-84 • How to Implement IS-IS on Cisco IOS XR Software, page RC-91 • Configuration Examples for Implementing IS-IS on Cisco IOS XR Software, page RC-122 • Where to Go Next, page RC-124 • Additional References, page RC-124 Cisco IOS XR Routing Configuration Guide RC-83 Implementing IS-IS on Cisco IOS XR Software Prerequisites for Implementing IS-IS on Cisco IOS XR Software Prerequisites for Implementing IS-IS on Cisco IOS XR Software The following are prerequisites for implementing IS-IS on Cisco IOS XR software: • You must be in a user group associated with a task group that includes the proper task IDs for IS-IS commands. Task IDs for commands are listed in the Cisco IOS XR Task ID Reference Guide. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide. Restrictions for Implementing IS-IS on Cisco IOS XR Software When multiple instances of IS-IS are being run, an interface can be associated with only one instance (process). Instances may not share an interface. Additionally, if Multiprotocol Label Switching traffic engineering (MPLS TE) is being employed, then MPLS must be enabled for only one instance. The MPLS process is not multi-instance aware. Information About Implementing IS-IS on Cisco IOS XR Software To implement IS-IS you need to understand the following concepts: • IS-IS Functional Overview, page RC-85 • Key Features Supported in the Cisco IOS XR IS-IS Implementation, page RC-85 • IS-IS Configuration Grouping, page RC-85 • Multitopology Configuration, page RC-86 • IPv6 Routing and Configuring IPv6 Addressing, page RC-86 • Limit LSP Flooding, page RC-86 • Maximum LSP Lifetime and Refresh Interval, page RC-87 • Overload Bit Configuration During Multitopology Operation, page RC-87 • Single-Topology IPv6 Support, page RC-87 • Multitopology IPv6 Support, page RC-88 • Nonstop Forwarding, page RC-88 • Multi-Instance IS-IS, page RC-89 • Multiprotocol Label Switching Traffic Engineering, page RC-89 • Overload Bit on Router, page RC-89 • Default Routes, page RC-90 • Attached Bit on an IS-IS Instance, page RC-90 Cisco IOS XR Routing Configuration Guide RC-84 Implementing IS-IS on Cisco IOS XR Software Information About Implementing IS-IS on Cisco IOS XR Software IS-IS Functional Overview Small IS-IS networks are typically built as a single area that includes all routers in the network. As the network grows larger, it may be reorganized into a backbone area made up of the connected set of all Level 2 routers from all areas, which is in turn connected to local areas. Within a local area, routers know how to reach all system IDs. Between areas, routers know how to reach the backbone, and the backbone routers know how to reach other areas. The IS-IS routing protocol supports the configuration of backbone Level 2 and Level 1 areas and the necessary support for moving routing information between the areas. Routers establish Level 1 adjacencies to perform routing within a local area (intra-area routing). Routers establish Level 2 adjacencies to perform routing between Level 1 areas (interarea routing). For Cisco IOS XR software, each IS-IS instance can support either a single Level 1 or Level 2 area, or one of each. By default, all IS-IS instances automatically support Level 1 and Level 2 routing. You can change the level of routing to be performed by a particular routing instance using the is-type command. Key Features Supported in the Cisco IOS XR IS-IS Implementation The Cisco IOS XR implementation of IS-IS conforms to the IS-IS Version 2 specifications detailed in RFC 1195 and the IPv6 IS-IS functionality based on the Internet Engineering Task Force (IETF) IS-IS Working Group draft-ietf-isis-ipv6.txt document. The following list outlines key features supported in the Cisco IOS XR implementation: • Improved configuration syntax and enhanced show commands • Single topology IPv6 • Multitopology • Nonstop forwarding (NSF), both Cisco proprietary and IETF • Three-way handshake • Mesh groups • Multiple IS-IS instances • Configuration of a broadcast medium connecting two networking devices as a point-to-point link IS-IS Configuration Grouping Cisco IOS XR groups all of the IS-IS configuration in router configuration mode, including the portion of the interface configurations associated with IS-IS. The grouping makes the configuration process clearer, and eliminates some of the clutter in the global interface stanza. To display the IS-IS configuration in its entirety, use the show isis interface command. The command output displays the running configuration for all configured IS-IS instances, including the interface assignments and interface attributes. Cisco IOS XR Routing Configuration Guide RC-85 Implementing IS-IS on Cisco IOS XR Software Information About Implementing IS-IS on Cisco IOS XR Software IS-IS Interfaces IS-IS interfaces can be configured as one of the following types: • active—advertises connected prefixes and forms adjacencies. This is the default for interfaces. • passive—advertises connected prefixes but does not form adjacencies. The passive command is used to configure interfaces as passive. Passive interfaces should be used sparingly for important prefixes such as loopback addresses that need to be injected into the IS-IS domain. If many connected prefixes need to be advertised then the redistribution of connected routes with the appropriate policy should be used instead. • suppressed—does not advertise connected prefixes but forms adjacencies. The suppress command is used to configure interfaces as suppressed. • shutdown—does not advertise connected prefixes and does not form adjacencies. The shutdown command is used to disable interfaces without removing the IS-IS configuration. Multitopology Configuration Cisco IOS XR software supports multitopology for IPv6 IS-IS unless single topology is explicitly configured in IPv6 address-family configuration mode. Note IS-IS supports IP routing and not Open Systems Interconnection (OSI) Connectionless Network Service (CLNS) routing. IPv6 Routing and Configuring IPv6 Addressing By default, IPv6 routing is disabled in the Cisco IOS XR software. To enable IPv6 routing, you must assign IPv6 addresses to individual interfaces in the router using the ipv6 enable or ipv6 address command. See the Network Stack IPv4 and IPv6 Commands on Cisco IOS XR Software module of the Cisco IOS XR IP Addresses and Services Command Reference. Limit LSP Flooding Limiting link-state packets (LSP) may be desirable in certain “meshy” network topologies. An example of such a network might be a highly redundant one such as a fully meshed set of point-to-point links over a nonbroadcast multiaccess (NBMA) transport. In such networks, full LSP flooding can limit network scalability. One way to restrict the size of the flooding domain is to introduce hierarchy by using multiple Level 1 areas and a Level 2 area. However, two other techniques can be used instead of or with hierarchy: Block flooding on specific interfaces and configure mesh groups. Both techniques operate by restricting the flooding of LSPs in some fashion. A direct consequence is that although scalability of the network is improved, the reliability of the network (in the face of failures) is reduced because a series of failures may prevent LSPs from being flooded throughout the network, even though links exist that would allow flooding if blocking or mesh groups had not restricted their use. In such a case, the link-state databases of different routers in the network may no longer be synchronized. Consequences such as persistent forwarding loops can ensue. For this reason, we recommend that blocking or mesh groups be used only if specifically required, and then only after careful network design. Cisco IOS XR Routing Configuration Guide RC-86 Implementing IS-IS on Cisco IOS XR Software Information About Implementing IS-IS on Cisco IOS XR Software Flood Blocking on Specific Interfaces With this technique, certain interfaces are blocked from being used for flooding LSPs, but the remaining interfaces operate normally for flooding. This technique is simple to understand and configure, but may be more difficult to maintain and more error prone than mesh groups in the long run. The flooding topology that IS-IS uses is fine-tuned rather than restricted. Restricting the topology too much (blocking too many interfaces) makes the network unreliable in the face of failures. Restricting the topology too little (blocking too few interfaces) may fail to achieve the desired scalability. To improve the robustness of the network in the event that all nonblocked interfaces drop, use the csnp-interval command in interface configuration mode to force periodic complete sequence number PDUs (CSNPs) packets to be used on blocked point-to-point links. The use of periodic CSNPs enables the network to become synchronized. Mesh Group Configuration Configuring mesh groups (a set of interfaces on a router) can help to limit flooding. All routers reachable over the interfaces in a particular mesh group are assumed to be densely connected with each router having at least one link to every other router. Many links can fail without isolating one or more routers from the network. In normal flooding, a new LSP is received on an interface and is flooded out over all other interfaces on the router. With mesh groups, when a new LSP is received over an interface that is part of a mesh group, the new LSP is not flooded over the other interfaces that are part of that mesh group. Maximum LSP Lifetime and Refresh Interval By default, the router sends a periodic LSP refresh every 15 minutes. LSPs remain in a database for 20 minutes by default. If they are not refreshed by that time, they are deleted. You can change the LSP refresh interval or maximum LSP lifetime. The LSP interval should be less than the LSP lifetime or else LSPs time out before they are refreshed. In the absence of a configured refresh interval, the software adjusts the LSP refresh interval, if necessary, to prevent the LSPs from timing out. Overload Bit Configuration During Multitopology Operation Because the overload bit applies to forwarding for a single topology, it may be configured and cleared independently for IPv4 and IPv6 during multitopology operation. For this reason, the overload is set from the router address family configuration mode. If the IPv4 overload bit is set, all routers in the area do not use the router for IPv4 transit traffic. However, they can still use the router for IPv6 transit traffic. Single-Topology IPv6 Support Single-topology IPv6 support on Cisco IOS XR software allows IS-IS for IPv6 to be configured on interfaces along with an IPv4 network protocol. All interfaces must be configured with the identical set of network protocols, and all routers in the IS-IS area (for Level 1 routing) or the domain (for Level 2 routing) must support the identical set of network layer protocols on all interfaces. Cisco IOS XR Routing Configuration Guide RC-87 Implementing IS-IS on Cisco IOS XR Software Information About Implementing IS-IS on Cisco IOS XR Software When single-topology support for IPv6 is used, only narrow link metrics, also known as old-style type, length, and value (TLV) arguments, may be employed. During single-topology operation, one shortest path first (SPF) computation for each level is used to compute both IPv4 and IPv6 routes. Using a single SPF is possible because both IPv4 IS-IS and IPv6 IS-IS routing protocols share a common link topology. Because multitopology is the default behavior in the software, you must explicitly configure IPv6 to use the same topology as IPv4 enable single-topology IPv6. Configure the single-topology command in IPv6 router address family configuration submode of the IS-IS router stanza. Multitopology IPv6 Support Multitopology IPv6 support on Cisco IOS XR software for IS-IS assumes that multitopology support is required as soon as it detects interfaces configured for both IPv6 and IPv4 within the IS-IS stanza. Nonstop Forwarding On Cisco IOS XR software, NSF minimizes the amount of time a network is unavailable to its users following a route processor (RP) failover. The main objective of NSF is to continue forwarding IP packets and perform a graceful restart following an RP failover. When a router restarts, all routing peers of that device usually detect that the device went down and then came back up. This transition results in what is called a routing flap, which could spread across multiple routing domains. Routing flaps caused by routing restarts create routing instabilities, which are detrimental to the overall network performance. NSF helps to suppress routing flaps in NSF-aware devices, thus reducing network instability. NSF allows for the forwarding of data packets to continue along known routes while the routing protocol information is being restored following an RP failover. When the NSF feature is configured, peer networking devices do not experience routing flaps. Data traffic is forwarded through intelligent line cards or dual forwarding processors (FPs) while the standby RP assumes control from the failed active RP during a failover. The ability of line cards and FPs to remain up through a failover and to be kept current with the Forwarding Information Base (FIB) on the active RP is key to NSF operation. When the Cisco IOS XR router running IS-IS routing performs an RP failover, the router must perform two tasks to resynchronize its link-state database with its IS-IS neighbors. First, it must relearn the available IS-IS neighbors on the network without causing a reset of the neighbor relationship. Second, it must reacquire the contents of the link-state database for the network. The IS-IS NSF feature offers two options when configuring NSF: • IETF NSF • Cisco NSF If neighbor routers on a network segment are NSF aware, meaning that neighbor routers are running a software version that supports the IETF Internet draft for router restartability, they assist an IETF NSF router that is restarting. With IETF NSF, neighbor routers provide adjacency and link-state information to help rebuild the routing information following a failover. In Cisco IOS XR software, Cisco NSF checkpoints (stores persistently) all the state necessary to recover from a restart without requiring any special cooperation from neighboring routers. The state is recovered from the neighboring routers, but only using the standard features of the IS-IS routing protocol. This capability makes Cisco NSF suitable for use in networks in which other routers have not used the IETF standard implementation of NSF. Cisco IOS XR Routing Configuration Guide RC-88 Implementing IS-IS on Cisco IOS XR Software Information About Implementing IS-IS on Cisco IOS XR Software Note If you configure IETF NSF on the Cisco IOS XR router and a neighbor router does not support IETF NSF, the affected adjacencies flap, but nonstop forwarding is maintained to all neighbors that do support IETF NSF. A restart reverts to a cold start if no neighbors support IETF NSF. Multi-Instance IS-IS You may configure as many IS-IS instances as system resources (memory and interfaces) allow. Each interface may be associated with only a single IS-IS instance, and MPLS may be enabled for only a single IS-IS instance. Cisco IOS XR software prevents the double-booking of an interface by two instances at configuration time—two instances of MPLS configuration causes an error. Because the Routing Information Base (RIB) treats each of the IS-IS instances as equal routing clients, you must be careful when redistributing routes between IS-IS instances. The RIB does not know to prefer Level 1 routes over Level 2 routes. For this reason, if you are running Level 1 and Level 2 instances, you must enforce the preference by configuring different administrative distances for the two instances. Multiprotocol Label Switching Traffic Engineering The MPLS TE feature enables an MPLS backbone to replicate and expand the traffic engineering capabilities of Layer 2 ATM and Frame Relay networks. MPLS is an integration of Layer 2 and Layer 3 technologies. For IS-IS, MPLS TE automatically establishes and maintains MPLS TE label-switched paths across the backbone by using Resource Reservation Protocol (RSVP). The route that a label-switched path uses is determined by the label-switched paths resource requirements and network resources, such as bandwidth. Available resources are flooded by using special IS-IS TLV extensions in the IS-IS. The label-switched paths are explicit routes and are referred to as traffic engineering (TE) tunnels. Overload Bit on Router The overload bit is a special bit of state information that is included in an LSP of the router. If the bit is set on the router, it notifies routers in the area that the router is not available for transit traffic. This capability is useful in four situations: 1. During a serious but nonfatal error, such as limited memory. 2. During the startup and restart of the process. The overload bit can be set until the routing protocol has converged. However, it is not employed during a normal NSF restart or failover because doing so causes a routing flap. 3. During a trial deployment of a new router. The overload bit can be set until deployment is verified, then cleared. 4. During the shutdown of a router. The overload bit can be set to remove the router from the topology before the router is removed from service. Cisco IOS XR Routing Configuration Guide RC-89 Implementing IS-IS on Cisco IOS XR Software Information About Implementing IS-IS on Cisco IOS XR Software Default Routes You can force a default route into an IS-IS routing domain. Whenever you specifically configure redistribution of routes into an IS-IS routing domain, the Cisco IOS XR software does not, by default, redistribute the default route into the IS-IS routing domain. The default-information originate command generates a default route into IS-IS, which can be controlled by a route map. You can use the route map to identify the level into which the default route is to be announced, and you can specify other filtering options configurable under a route map. You can use a route map to conditionally advertise the default route, depending on the existence of another route in the routing table of the router. Attached Bit on an IS-IS Instance The attached bit is set in a router that is configured with the is-type command and level-1-2 keyword. The attached bit indicates that the router is connected to other areas (typically through the backbone). This functionality means that the router can be used by Level 1 routers in the area as the default route to the backbone. The attached bit is usually set automatically as the router discovers other areas while computing its Level 2 SPF route. The bit is automatically cleared when the router becomes detached from the backbone. To simulate this behavior when using multiple processes to represent the level-1-2 keyword functionality, you would manually configure the attached bit on the Level 1 process. Caution If the connectivity for the Level 2 instance is lost, the attached bit in the Level 1 instance LSP would continue sending traffic to the Level 2 instance and cause the traffic to be dropped. Multicast-Intact Feature The multicast-intact feature provides the ability to run multicast routing (PIM) when IGP shortcuts are configured and active on the router. Both OSPFv2 and IS-IS support the multicast-intact feature. You can enable multicast-intact in the IGP when multicast routing protocols (PIM) are configured and IGP shortcuts are configured on the router. IGP shortcuts are MPLS tunnels that are exposed to IGP. The IGPs route the IP traffic over these tunnels to destinations that are downstream from the egress router of the tunnel (from an SPF perspective). PIM cannot use IGP shortcuts for propagating PIM joins because reverse path forwarding (RPF) cannot work across a unidirectional tunnel. When you enable multicast-intact on an IGP, the IGP publishes a parallel or alternate set of equal-cost next-hops for use by PIM. These next-hops are called mcast-intact next-hops. The mcast-intact next-hops have the following attributes: • They are guaranteed not to contain any IGP shortcuts. • They are not used for unicast routing but are used only by PIM to look up an IPv4 next-hop to a PIM source. • They are not published to the FIB. • When multicast-intact is enabled on an IGP, all IPv4 destinations that were learned through link-state advertisements are published with a set equal-cost mcast-intact next-hops to the RIB. This attribute applies even when the native next-hops have no IGP shortcuts. • In IS-IS, the max-paths limit is applied by counting both the native and mcast-intact next-hops together. (In OSPFv2, the behavior is slightly different.) Cisco IOS XR Routing Configuration Guide RC-90 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software This section contains the following procedures: Note • Enabling IS-IS and Configuring Level 1 or Level 2 Routing, page RC-91 (required) • Configuring Single Topology for IS-IS, page RC-93 (required) • Configuring Multitopology for IS-IS, page RC-98 (optional) • Controlling LSP Flooding for IS-IS, page RC-102 (optional) • Configuring Nonstop Forwarding for IS-IS, page RC-106 (optional) • Configuring Authentication for IS-IS, page RC-108 (optional) • Configuring MPLS Traffic Engineering for IS-IS, page RC-110 (optional) • Tuning Adjacencies for IS-IS on Point-to-Point Interfaces, page RC-113 (optional) • Setting SPF Interval for a Single-Topology IPv4 and IPv6 Configuration, page RC-116 (optional) • Enabling Multicast-Intact for IS-IS, page RC-118 (optional) To save configuration changes, you must commit changes when the system prompts you. Enabling IS-IS and Configuring Level 1 or Level 2 Routing This task explains how to enable IS-IS and configure the routing level for an area. Note Configuring the routing level in Step 4 is optional, but is highly recommended to establish the proper level of adjacencies. Prerequisites Although you can configure IS-IS before you configure an IP address, no IS-IS routing occurs until at least one IP address is configured. SUMMARY STEPS 1. configure 2. router isis instance-id 3. net network-entity-title 4. is-type {level-1 | level-1-2 | level-2-only} 5. end or commit 6. show isis [instance instance-id] protocol Cisco IOS XR Routing Configuration Guide RC-91 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router isis instance-id Example: Enables IS-IS routing for the specified routing instance, and places the router in router configuration mode. • RP/0/RP0/CPU0:router(config)# router isis isp Step 3 net network-entity-title Example: Configures network entity titles (NETs) for the routing instance. • Specify a NET for each routing instance if you are configuring multi-instance IS-IS. You can specify a name for a NET and for an address. • This example configures a router with area ID 47.0004.004d.0001 and system ID 0001.0c11.1110.00. • To specify more than one area address, specify additional NETs. Although the area address portion of the NET differs, the systemID portion of the NET must match exactly for all of the configured items. RP/0/RP0/CPU0:router(config-isis)# net 47.0004.004d.0001.0001.0c11.1110.00 Step 4 is-type {level-1 | level-1-2 | level-2-only} Example: (Optional) Configures the system type (area or backbone router). • By default, every IS-IS instance acts as a level-1-2 router. • The level-1 keyword configures the software to perform Level 1 (intra-area) routing only. Only Level 1 adjacencies are established. The software learns about destinations inside its area only. Any packets containing destinations outside the area are sent to the nearest level-1-2 router in the area. • The level-2-only keyword configures the software to perform Level 2 (backbone) routing only, and the router establishes only Level 2 adjacencies, either with other Level 2-only routers or with level-1-2 routers. • The level-1-2 keyword configures the software to perform both Level 1 and Level 2 routing. Both Level 1 and Level 2 adjacencies are established. The router acts as a border router between the Level 2 backbone and its Level 1 area. RP/0/RP0/CPU0:router(config-isis)# is-type level-2-only Cisco IOS XR Routing Configuration Guide RC-92 By default, all IS-IS instances are automatically Level 1 and Level 2. You can change the level of routing to be performed by a particular routing instance using the is-type router configuration command. Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Step 5 Command or Action Purpose end Saves configuration changes. or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-isis)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-isis)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Step 6 show isis [instance instance-id] protocol Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. (Optional) Displays summary information about the IS-IS instance. Example: RP/0/RP0/CPU0:router# show isis protocol Configuring Single Topology for IS-IS After an IS-IS instance is enabled, it must be configured to compute routes for a specific network topology. This task explains how to configure the operation of the IS-IS protocol on an interface for an IPv4 or IPv6 topology. Restrictions To enable the router to run in single-topology mode, configure each of the IS-IS interfaces with all of the address families enabled and “single-topology” in the address-family IPv6 unicast in the IS-IS router stanza. You can use either the IPv6 address family or both IPv4 and IPv6 address families, but your configuration must represent the set of all active address families on the router. In addition, you should explicitly enable single-topology operation by configuring it in the IPv6 router address family submode. Exceptions to these instructions exist: 1. If the address-family stanza in the IS-IS process contains the adjacency-check disable command, then an interface is not required to have the address family enabled. 2. If the interface is configured to Level 2 only. (This exception permits the running of IPv4 and IPv6 areas.) 3. The single-topology command is not valid in the ipv4 address-family submode. Cisco IOS XR Routing Configuration Guide RC-93 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software The default metric style for single topology is narrow metrics. However, you can use either wide metrics or narrow metrics. How to configure them depends on how single topology is configured. If both IPv4 and IPv6 are enabled and single topology is configured, the metric style is configured in the address-family ipv4 stanza. You may configure the metric style in the address-family ipv6 stanza, but it is ignored in this case. If only IPv6 is enabled and single topology is configured, then the metric style is configured in the address-family ipv6 stanza. SUMMARY STEPS 1. configure 2. interface type number 3. ipv4 address address mask or ipv6 address ipv6-prefix/prefix-length [eui-64] or ipv6 address ipv6-address {/prefix-length | link-local} or ipv6 enable 4. exit 5. router isis instance-id 6. net network-entity-title 7. address-family ipv6 [unicast] 8. single-topology 9. exit 10. interface type instance 11. circuit-type {level-1 | level-1-2 | level-2-only} 12. address-family {ipv4 | ipv6} [unicast] 13. end or commit 14. show isis [instance instance-id] interface [type instance] [detail] [level {1 | 2}] 15. show isis [instance instance-id] topology [systemid system-id] [level {1 | 2}] [summary] Cisco IOS XR Routing Configuration Guide RC-94 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 interface type number Enters interface configuration mode. Example: RP/0/RP0/CPU0:router(config)# interface POS 0/1/0/3 Step 3 ipv6 address ipv6-prefix/prefix-length [eui-64] Defines the IPv4 address for the interface. An IP address is required on all interfaces in an area enabled for IS-IS if any one interface is configured for IS-IS routing. or or ipv6 address ipv6-address {/prefix-length | link-local} Specifies an IPv6 network assigned to the interface and enables IPv6 processing on the interface with the eui-64 keyword. ipv4 address address mask or or ipv6 enable or Example: RP/0/RP0/CPU0:router(config-if)# ipv4 address 10.0.1.3 255.255.255.0 or RP/0/RP0/CPU0:router(config-if)# ipv6 address 3ffe:1234:c18:1::/64 eui-64 or RP/0/RP0/CPU0:router(config-if)# ipv6 address FE80::260:3EFF:FE11:6770 link-local Specifies an IPv6 address assigned to the interface and enables IPv6 processing on the interface with the link-local keyword. or Automatically configures an IPv6 link-local address on the interface while also enabling the interface for IPv6 processing. • The link-local address can be used only to communicate with nodes on the same link. • Specifying the ipv6 address ipv6-prefix/prefix-length interface configuration command without the eui-64 keyword configures site-local and global IPv6 addresses. • Specifying the ipv6 address ipv6-prefix/prefix-length command with the eui-64 keyword configures site-local and global IPv6 addresses with an interface ID in the low-order 64 bits of the IPv6 address. Only the 64-bit network prefix for the address needs to be specified; the last 64 bits are automatically computed from the interface ID. • Specifying the ipv6 address command with the link-local keyword configures a link-local address on the interface that is used instead of the link-local address that is automatically configured when IPv6 is enabled on the interface. or RP/0/RP0/CPU0:router(config-if)# ipv6 enable Cisco IOS XR Routing Configuration Guide RC-95 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Step 4 Command or Action Purpose exit Exits interface configuration mode, and returns the router to global configuration mode. Example: RP/0/RP0/CPU0:router(config-if)# exit Step 5 router isis instance-id Example: Enables IS-IS routing for the specified routing instance, and places the router in router configuration mode. • RP/0/RP0/CPU0:router(config)# router isis isp Step 6 net network-entity-title Configures NETs for the routing instance. • Specify a NET for each routing instance if you are configuring multi-instance IS-IS. You can specify a name for a NET and for an address. • This example configures a router with area ID 47.0004.004d.0001 and system ID 0001.0c11.1110.00. • To specify more than one area address, specify additional NETs. Although the area address portion of the NET differs, the system ID portion of the NET must match exactly for all of the configured items. Example: RP/0/RP0/CPU0:router(config-isis)# net 47.0004.004d.0001.0001.0c11.1110.00 Step 7 address-family ipv6 [unicast] Example: By default, all IS-IS instances are Level 1 and Level 2. You can change the level of routing to be performed by a particular routing instance using the is-type command. Specifies the IPv6 address family and enters router address family configuration mode. • This example specifies the unicast IPv6 address family. RP/0/RP0/CPU0:router(config-isis)# address-family ipv6 unicast Step 8 single-topology Example: (Optional) Configures the link topology for IPv4 when IPv6 is configured. • The single-topology command is valid only in IPv6 submode. The command instructs IPv6 to use the single topology rather than the default configuration of a separate topology in the multitopology mode. • See the “Single-Topology IPv6 Support” section on page RC-87 for more information. RP0/0/RP0/CPU0:router(config-isis-af)# single-topology Step 9 Exits router address family configuration mode, and returns the router to router configuration mode. exit Example: RP/0/RP0/CPU0:router(config-isis-af)# exit Step 10 interface type instance Example: RP/0/RP0/CPU0:router(config-isis)# interface POS 0/1/0/3 Cisco IOS XR Routing Configuration Guide RC-96 Enters interface configuration mode. Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Step 11 Command or Action Purpose circuit-type {level-1 | level-1-2 | level-2-only} (Optional) Configures the type of adjacency. Example: RP/0/RP0/CPU0:router(config-isis-if)# circuit-type level-1-2 Step 12 address-family {ipv4 | ipv6} [unicast] Example: • The default circuit type is the configured system type (configured through the is-type command). • Typically, the circuit type must be configured when the router is configured as only level-1-2 and you want to constrain an interface to form only level-1 or level-2-only adjacencies. Specifies the IPv4 or IPv6 address family, and enters interface address family configuration mode. • RP/0/RP0/CPU0:router(config-isis-if)# address-family ipv6 unicast Step 13 end or This example specifies the unicast IPv6 address family on the interface. Saves configuration changes. commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-isis-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-isis-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Step 14 show isis [instance instance-id] interface [type instance] [detail] [level {1 | 2}] Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. (Optional) Displays information about the IS-IS interface. Example: RP/0/RP0/CPU0:router# show isis interface POS0/1/0/1 Step 15 show isis [instance instance-id] topology [systemid system-id] [level {1 | 2}] [summary] (Optional) Displays a list of connected routers in all areas. Example: RP/0/RP0/CPU0:router# show isis topology Cisco IOS XR Routing Configuration Guide RC-97 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Configuring Multitopology for IS-IS This task explains how to configure multitopology IS-IS. This task is optional. Multitopology is configured in much the same way as the single topology for IPv4 and IPv6 address families. The singletopology command is omitted, invoking the default multitopology behavior. SUMMARY STEPS 1. configure 2. interface type instance 3. ipv4 address address mask or ipv6 address ipv6-prefix/prefix-length [eui-64] or ipv6 address ipv6-address {/prefix-length | link-local} or ipv6 enable 4. exit 5. router isis instance-id 6. net network-entity-title 7. interface type instance 8. address-family ipv4 [unicast] 9. exit 10. address-family ipv6 [unicast] 11. end or commit 12. show isis [instance instance-id] interface [type number] [brief | detail] [level {1 | 2}] 13. show isis [instance instance-id] topology [systemid system-id] [level {1 | 2}] [ipv4 | ipv6] [summary] [unicast] 14. show isis [instance instance-id] adjacency [level {1 | 2}] [interface-type interface-instance] [detail] [systemid system-id] 15. show isis adjacency-log [level {1 | 2}] Cisco IOS XR Routing Configuration Guide RC-98 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 interface type instance Enters interface configuration mode. Example: RP/0/RP0/CPU0:router(config)# interface POS 0/1/0/3 Step 3 ipv4 address address mask or Defines the IPv4 address for the interface. • ipv6 address ipv6-prefix/prefix-length [eui-64] or ipv6 address ipv6-address {/prefix-length | link-local} or ipv6 enable An IP address is required on all interfaces in an area enabled for IS-IS if any one interface is configured for IS-IS routing. or Specifies an IPv6 network assigned to the interface and enables IPv6 processing on the interface. or Example: RP/0/RP0/CPU0:router(config-if)# ipv4 address 10.0.1.3 255.255.255.0 or RP/0/RP0/CPU0:router(config-if)# ipv6 address 3ffe:1234:c18:1::/64 eui-64 or RP/0/RP0/CPU0:router(config-if)# ipv6 address FE80::260:3EFF:FE11:6770 link-local Specifies an IPv6 address assigned to the interface and enables IPv6 processing on the interface. or Automatically configures an IPv6 link-local address on the interface while also enabling the interface for IPv6 processing. • The link-local address can be used to communicate only with nodes on the same link. • Specifying the ipv6 address ipv6-prefix/prefix-length interface configuration command without the eui-64 keyword configures site-local and global IPv6 addresses. • Specifying the ipv6 address ipv6-prefix/prefix-length command with the eui-64 keyword configures site-local and global IPv6 addresses with an interface ID in the low-order 64 bits of the IPv6 address. Only the 64-bit network prefix for the address needs to be specified; the last 64 bits are automatically computed from the interface ID. • Specifying the ipv6 address command with the link-local keyword configures a link-local address on the interface that is used instead of the link-local address that is automatically configured when IPv6 is enabled on the interface. or RP/0/RP0/CPU0:router(config-if)# ipv6 enable Cisco IOS XR Routing Configuration Guide RC-99 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Step 4 Command or Action Purpose exit Exits interface configuration mode, and returns the router to global configuration mode. Example: RP/0/RP0/CPU0:router(config-if)# exit Step 5 router isis instance-id Example: Enables IS-IS routing for the specified routing instance, and places the router in router configuration mode. • RP/0/RP0/CPU0:router(config)# router isis isp Step 6 net network-entity-title Configures NETs for the routing instance. • Specify a NET for each routing instance if you are configuring multi-instance IS-IS. You can specify a name for a NET and for an address. • This example configures a router with area ID 47.0004.004d.0001 and system ID 0001.0c11.1110.10. • To specify more than one area address, specify additional NETs. Although the area address portion of the NET differs, the system ID portion of the NET must match exactly for all of the configured items. Example: RP/0/RP0/CPU0:router(config-isis)# net 47.0004.004d.0001.0001.0c11.1110.00 Step 7 interface type instance You can change the level of routing to be performed by a particular routing instance using the is-type router configuration command. Enters interface configuration mode. Example: RP/0/RP0/CPU0:router(config-isis)# interface POS 0/1/0/4 Step 8 address-family ipv4 [unicast] Example: Specifies the IPv4 address family and enters interface address family configuration mode. • This example specifies the unicast IPv4 address family. RP/0/RP0/CPU0:router(config-isis-if)# address-family ipv4 unicast Step 9 Exits interface configuration mode, and returns the router to interface configuration mode. exit Example: RP/0/RP0/CPU0:router(config-if)# exit Step 10 address-family ipv6 [unicast] Example: RP/0/RP0/CPU0:router(config-isis-if)# address-family ipv6 unicast Cisco IOS XR Routing Configuration Guide RC-100 Specifies the IPv6 address family and enters interface address family configuration mode. • This example specifies the unicast IPv6 address family. Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Step 11 Command or Action Purpose end Saves configuration changes. or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-isis-if-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-isis-if-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Step 12 show isis [instance instance-id] interface [type instance] [brief | detail] [level {1 | 2}] Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. (Optional) Displays information about the IS-IS interface. Example: RP/0/RP0/CPU0:router# show isis interface POS 0/1/0/1 brief Step 13 show isis [instance instance-id] topology [systemid system-id] [level {1 | 2}] [ipv4 | ipv6] [summary] [unicast] (Optional) Displays a list of connected routers in all areas. Example: RP/0/RP0/CPU0:router# show isis topology Step 14 show isis [instance instance-id] adjacency [level {1 | 2}] [interface-type interface-instance] [detail] [systemid system-id] (Optional) Displays state information about established adjacencies. Example:: RP/0/RP0/CPU0:router# show isis adjacency Step 15 show isis adjacency-log [level {1 | 2}] (Optional) Displays the history of recent adjacency state transitions. Example: RP/0/RP0/CPU0:router# show isis adjacency-log level 1 Cisco IOS XR Routing Configuration Guide RC-101 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Controlling LSP Flooding for IS-IS Flooding of LSPs can limit network scalability. You can control LSP flooding by tuning your LSP database parameters on the router globally or on the interface. This task is optional. Many of the commands to control LSP flooding contain an option to specify the level to which they apply. Without the option, the command applies to both levels. If an option is configured for one level, the other level continues to use the default value. To configure options for both levels, use the command twice. For example: RP/0/RP0/CPU0:router(config-isis)# lsp-refresh-interval 1200 level 2 RP/0/RP0/CPU0:router(config-isis)# lsp-refresh-interval 1100 level 1 SUMMARY STEPS 1. configure 2. router isis instance-id 3. lsp-refresh-interval seconds [level {1 | 2}] 4. lsp-check-interval seconds [level {1 | 2}] 5. lsp-gen-interval {[initial-wait initial | secondary-wait secondary | maximum-wait maximum] ...}[level {1 | 2}] 6. lsp-mtu bytes [level {1 | 2}] 7. max-lsp-lifetime seconds [level {1 | 2}] 8. ignore-lsp-errors disable 9. interface type instance 10. lsp-interval milliseconds [level {1 | 2}] 11. csnp-interval seconds [level {1 | 2}] 12. retransmit-interval seconds [level {1 | 2}] 13. retransmit-throttle-interval milliseconds [level {1 | 2}] 14. mesh-group {number | blocked} 15. end or commit 16. show isis interface [type instance | level {1 | 2}] [brief] 17. show isis [instance instance-id] database [level {1 | 2}] [detail | summary | verbose] [* | lsp-id] 18. show isis [instance instance-id] lsp-log [level {1 | 2}] 19. show isis database-log [level {1 | 2}] Cisco IOS XR Routing Configuration Guide RC-102 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 Enables IS-IS routing for the specified routing instance, and places the router in router configuration mode. router isis instance-id • Example: RP/0/RP0/CPU0:router(config)# router isis isp Step 3 lsp-refresh-interval seconds [level {1 | 2}] (Optional) Sets the time between regeneration of LSPs that contain different sequence numbers • Example: RP/0/RP0/CPU0:router(config-isis)# lsp-refresh-interval 10800 Step 4 lsp-check-interval seconds [level {1 | 2}] Example: Step 5 lsp-gen-interval {[ initial-wait initial secondary-wait secondary | maximum-wait maximum ] ...}[level { 1 | 2 }] | Example: lsp-mtu bytes [level {1 | 2}] This operation is costly in terms of CPU and so should be configured to occur infrequently. (Optional) Reduces the rate of LSP generation during periods of instability in the network. Helps reduce the CPU load on the router and number of LSP transmissions to its IS-IS neighbors. • RP/0/RP0/CPU0:router(config-isis)# lsp-gen-interval maximum-wait 15 initial-wait 5 Step 6 The refresh interval should always be set lower than the max-lsp-lifetime command. (Optional) Configures the time between periodic checks of the entire database to validate the checksums of the LSPs in the database. • RP/0/RP0/CPU0:router(config-isis)# lsp-check-interval 240 You can change the level of routing to be performed by a particular routing instance using the is-type router configuration command. During prolonged periods of network instability, repeated recalculation of LSPs can cause an increased CPU load on the local router. Further, the flooding of these recalculated LSPs to the other Intermediate Systems in the network causes increased traffic and can result in other routers having to spend more time running route calculations. (Optional) Sets the maximum transmission unit (MTU) size of LSPs. Example: RP/0/RP0/CPU0:router(config-isis)# lsp-mtu 1300 Step 7 max-lsp-lifetime seconds [level {1 | 2}] Example: RP/0/RP0/CPU0:router(config-isis)# max-lsp-lifetime 11000 (Optional) Sets the initial lifetime given to an LSP originated by the router. • This is the amount of time that the LSP persists in the database of a neighbor unless the LSP is regenerated or refreshed. Cisco IOS XR Routing Configuration Guide RC-103 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Step 8 Command or Action Purpose ignore-lsp-errors disable (Optional) Sets the router to purge LSPs received with checksum errors. Example: RP/0/RP0/CPU0:router(config-isis)# ignore-lsp-errors disable Step 9 interface type instance Enters interface configuration mode. Example: RP/0/RP0/CPU0:router(config-isis)# interface POS 0/1/0/3 Step 10 lsp-interval milliseconds [level {1 | 2}] (Optional) Configures the amount of time between each LSP sent on an interface. Example: RP/0/RP0/CPU0:router(config-isis-if)# lsp-interval 100 Step 11 csnp-interval seconds [level {1 | 2}] Example: (Optional) Configures the interval at which periodic CSNP packets are sent on broadcast interfaces. • Sending more frequent CSNPs means that adjacent routers must work harder to receive them. • Sending less frequent CSNP means that differences in the adjacent routers may persist longer. RP/0/RP0/CPU0:router(config-isis-if)# csnp-interval 30 level 1 Step 12 retransmit-interval seconds [level {1 | 2}] Example: (Optional) Configures the amount of time that the sending router waits for an acknowledgment before it considers that the LSP was not received and subsequently resends. RP/0/RP0/CPU0:router(config-isis-if)# retransmit-interval 60 Step 13 retransmit-throttle-interval milliseconds [level {1 | 2}] (Optional) Configures the amount of time between retransmissions on each LSP on a point-to-point interface. • Example: RP/0/RP0/CPU0:router(config-isis-if)# retransmit-throttle-interval 1000 Step 14 mesh-group {number | blocked} Example: RP/0/RP0/CPU0:router(config-isis-if)# mesh-group blocked Cisco IOS XR Routing Configuration Guide RC-104 This time is usually greater than or equal to the lsp-interval command time because the reason for lost LSPs may be that a neighboring router is busy. A longer interval gives the neighbor more time to receive transmissions. (Optional) Optimizes LSP flooding in NBMA networks with highly meshed, point-to-point topologies. • This command is appropriate only for an NBMA network with highly meshed, point-to-point topologies. Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Step 15 Command or Action Purpose end Saves configuration changes. or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-isis-if)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-isis-if)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Step 16 show isis interface [type instance | level {1 | 2}] [brief] Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. (Optional) Displays information about the IS-IS interface. Example: RP/0/RP0/CPU0:router# show isis interface POS0/1/0/1 brief Step 17 show isis [instance instance-id] database [level {1 | 2}] [detail | summary | verbose] [* | lsp-id] (Optional) Displays the IS-IS LSP database. Example: RP/0/RP0/CPU0:router# show isis database level 1 Step 18 show isis [instance instance-id] lsp-log [level {1 | 2}] (Optional) Displays LSP log information. Example: RP/0/RP0/CPU0:router# show isis lsp-log Step 19 show isis database-log [level {1 | 2}] (Optional) Display IS-IS database log information. Example: RP/0/RP0/CPU0:router# show isis database-log level 1 Cisco IOS XR Routing Configuration Guide RC-105 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Configuring Nonstop Forwarding for IS-IS This task explains how to configure your router with NSF that allows the Cisco IOS XR software to resynchronize the IS-IS link-state database with its IS-IS neighbors after a process restart. The process restart could be due to an: • RP failover (for a warm restart) • Simple process restart (due to an IS-IS reload or other administrative request to restart the process) • IS-IS software upgrade In all cases, NSF mitigates link flaps and loss of user sessions. This task is optional. SUMMARY STEPS 1. configure 2. router isis instance-id 3. nsf {cisco | ietf} 4. nsf interface-expires number 5. nsf interface-timer seconds 6. nsf lifetime seconds 7. end or commit 8. show running-config [command] DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router isis instance-id Example: Enables IS-IS routing for the specified routing instance, and places the router in router configuration mode. • RP/0/RP0/CPU0:router(config)# router isis isp Step 3 nsf {cisco | ietf} Enables NSF on the next restart. • Enter the cisco keyword to run IS-IS in heterogeneous networks that might not have adjacent NSF-aware networking devices. • Enter the ietf keyword to enable IS-IS in homogeneous networks where all adjacent networking devices support IETF draft-based restartability. Example: RP/0/RP0/CPU0:router(config-isis)# nsf ietf Cisco IOS XR Routing Configuration Guide RC-106 You can change the level of routing to be performed by a particular routing instance using the is-type router configuration command. Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Step 4 Command or Action Purpose nsf interface-expires number Configures the number of resends of an acknowledged NSF-restart acknowledgment. Example: • RP/0/RP0/CPU0:router(config-isis)# nsf interface-expires 1 Step 5 nsf interface-timer seconds If the resend limit is reached during the NSF restart, the restart falls back to a cold restart. Configures the number of seconds to wait for each restart acknowledgment. Example: RP/0/RP0/CPU0:router(config-isis) nsf interface-timer 15 Step 6 nsf lifetime seconds Example: Configures the maximum route lifetime following an NSF restart. • This command should be configured to the length of time required to perform a full NSF restart because it is the amount of time that the Routing Information Base (RIB) retains the routes during the restart. • Setting this value too high results in stale routes. • Setting this value too low could result in routes purged too soon. RP/0/RP0/CPU0:router(config-isis)# nsf lifetime 20 Step 7 end or Saves configuration changes. commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-isis)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-isis)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Step 8 show running-config [command] Example: Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. (Optional) Displays the entire contents of the currently running configuration file or a subset of that file. • Verify that “nsf” appears in the IS-IS configuration of the NSF-aware device. • This example shows the contents of the configuration file for the “isp” instance only. RP/0/RP0/CPU0:router# show running-config router isis isp Cisco IOS XR Routing Configuration Guide RC-107 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Configuring Authentication for IS-IS This task explains how to configure authentication for IS-IS. This task is optional. Authentication is available to limit the establishment of adjacencies by using the hello-password configuration, and to limit the exchange of LSPs by using the LSP password. IS-IS supports plain-text authentication, which does not provide security against hackers or other unauthorized users. Plain-text authentication allows you to configure a password to prevent unauthorized networking devices from forming adjacencies with this router. The password is exchanged as plain text and is potentially visible to an agent able to view the IS-IS packets. IS-IS stores a configured password using simple encryption. However, the plain-text form of the password is used in LSPs, sequence number protocols (SNPs), and hello packets, which would be visible to a process that can view IS-IS packets. The passwords can be entered in plain text (preceded by a 0) or encrypted (preceded by a 7) form. To set the domain password, configure the lsp-password for Level 2; to set the area password, configure the lsp-password for Level 1. SUMMARY STEPS 1. configure 2. router isis instance-id 3. lsp-password {hmac-md5 | text} {clear | encrypted} password [level {1 | 2}] [send-only] [snp send-only] 4. interface type instance 5. hello-password {hmac-md5 | text} {clear | encrypted} password [level {1 | 2}] [send-only] 6. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router isis instance-id Example: RP/0/RP0/CPU0:router(config)# router isis isp Cisco IOS XR Routing Configuration Guide RC-108 Enables IS-IS routing for the specified routing instance, and places the router in router configuration mode. • You can change the level of routing to be performed by a particular routing instance using the is-type command. Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Step 3 Command or Action Purpose lsp-password {hmac-md5 | text} {clear | encrypted} password [level {1 | 2}] [send-only] [snp send-only] Configures the LSP authentication password. Example: RP/0/RP0/CPU0:router(config-isis)# lsp-password hmac-md5 encrypted password1 level 1 Step 4 interface type instance • The hmac-md5 keyword specifies that the password is used in HMAC-MD5 authentication. • The text keyword specifies that the password uses cleartext password authentication. • The clear keyword specifies that the password is unencrypted when entered. • The encrypted keyword specifies that the password is encrypted using a two-way algorithm when entered. • The level 1 keyword sets a password for authentication in the area (in Level 1 LSPs and Level SNPs). • The level 2 keywords set a password for authentication in the backbone (the Level 2 area). • The send-only keyword adds authentication to LSP and sequence number protocol data units (SNPs) when they are sent. It does not authenticate received LSPs or SNPs. • The snp send-only keyword adds authentication to SNPs when they are sent. It does not authenticate received SNPs. Note To disable SNP password checking, the snp send-only keywords must be specified in the lsp-password command. Enters interface configuration mode. Example: RP/0/RP0/CPU0:router(config-isis)# interface POS 0/1/0/3 Cisco IOS XR Routing Configuration Guide RC-109 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Step 5 Command or Action Purpose hello-password {hmac-md5 | text} {clear | encrypted} password [level {1 | 2}] [send-only] Configures the authentication password for an IS-IS interface. Example: RP/0/RP0/CPU1:router(config-isis-if)# hello-password text clear mypassword Step 6 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-isis-if)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-isis-if)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Configuring MPLS Traffic Engineering for IS-IS This task explains how to configure IS-IS for MPLS TE. This task is optional. For a description of the MPLS TE tasks and commands that allow you to configure the router to support tunnels, configure an MPLS tunnel that IS-IS can use, and troubleshoot MPLS TE, see the Implementing MPLS Traffic Engineering on Cisco IOS XR Software. Prerequisite Your network must support the following Cisco IOS XR software features before you enable MPLS TE for IS-IS on your router: Note • MPLS • IP Cisco Express Forwarding (CEF) You must enter the commands in the following task list on every IS-IS router in the traffic-engineered portion of your network. Cisco IOS XR Routing Configuration Guide RC-110 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Restrictions MPLS traffic engineering currently supports only a single IS-IS level and does not support routing and signaling of LSPs over unnumbered IP links. Therefore, do not configure the feature over those links. SUMMARY STEPS 1. configure 2. router isis instance-id 3. address-family {ipv4 | ipv6} [unicast] 4. mpls traffic-eng level {1 | 2} 5. mpls traffic-eng router-id {ip-address | interface-name} 6. metric-style wide [level {1 | 2}] 7. end or commit 8. show isis [instance instance-id] mpls traffic-eng tunnel 9. show isis [instance instance-id] mpls traffic-eng adjacency-log 10. show isis [instance instance-id] mpls traffic-eng advertisements DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router isis instance-id Example: Enables IS-IS routing for the specified routing instance, and places the router in router configuration mode. • RP/0/RP0/CPU0:router(config)# router isis isp Step 3 address-family {ipv4 | ipv6} [unicast] Example: You can change the level of routing to be performed by a particular routing instance using the is-type router configuration command. Specifies the IPv4 or IPv6 address family, and enters router address family configuration mode. • This example specifies the unicast IPv6 address family. RP/0/RP0/CPU0:router(config-isis)# address-family ipv6 unicast Step 4 mpls traffic-eng level {1 | 2} Configures a router running IS-IS to flood MPLS TE link information into the indicated IS-IS level. Example: RP/0/RP0/CPU0:router(config-isis-af)# mpls traffic-eng level 1 Cisco IOS XR Routing Configuration Guide RC-111 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Step 5 Command or Action Purpose mpls traffic-eng router-id {ip-address | interface-name} Specifies that the MPLS TE router identifier for the node is the IP address and or name associated with a given interface. Example: RP/0/RP0/CPU0:router(config-isis-af)# mpls traffic-eng router-id loopback0 Step 6 metric-style wide [level {1 | 2}] Configures a router to generate and accept only wide link metrics in the Level 1 area. Example: RP/0/RP0/CPU0:router(config-isis-af)# metric-style wide level 1 Step 7 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-isis-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-isis-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Step 8 show isis [instance instance-id] mpls traffic-eng tunnel Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. (Optional) Displays MPLS TE tunnel information. Example: RP/0/RP0/CPU0:router# show isis instance isp mpls traffic-eng tunnel Step 9 show isis [instance instance-id] mpls traffic-eng adjacency-log (Optional) Displays a log of MPLS TE IS-IS adjacency changes. Example: RP/0/RP0/CPU0:router# show isis instance isp mpls traffic-eng adjacency-log Step 10 show isis [instance instance-id] mpls traffic-eng advertisements Example: RP/0/RP0/CPU0:router# show isis instance isp mpls traffic-eng advertisements Cisco IOS XR Routing Configuration Guide RC-112 (Optional) Displays the latest flooded record from MPLS TE. Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Tuning Adjacencies for IS-IS on Point-to-Point Interfaces This task explains how to enable logging of adjacency state changes, alter the timers for IS-IS adjacency packets, and display various aspects of adjacency state. Tuning your IS-IS adjacencies increases network stability when links are congested. This task is optional. For point-to-point links, IS-IS sends only a single hello for Level 1 and Level 2, which means that the level modifiers are meaningless on point-to-point links. To modify hello parameters for a point-to-point interface, omit the specification of the level options. The options configurable in the interface submode apply only to that interface. By default, the values are applied to both Level 1 and Level 2. The hello-password command can be used to prevent adjacency formation with unauthorized or undesired routers. This ability is particularly useful on a LAN, where connections to routers with which you have no desire to establish adjacencies are commonly found. SUMMARY STEPS 1. configure 2. router isis instance-id 3. log adjacency changes 4. interface type number 5. hello-padding {disable | sometimes} [level {1 | 2}] 6. hello-interval seconds [level {1 | 2}] 7. hello-multiplier multiplier [level {1 | 2}] 8. hello-password {hmac-md5 | text} {clear | encrypted} password [level {1 | 2}] [send-only] 9. end or commit 10. show isis [instance instance-id] adjacency [interface-type interface-instance] [detail] [systemid system-id] 11. show isis adjacency-log 12. show isis [instance instance-id] interface [type instance] [brief | detail] [level {1 | 2}] 13. show isis [instance instance-id] neighbors [interface-type interface-instance] [summary] [detail] [systemid system-id] Cisco IOS XR Routing Configuration Guide RC-113 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router isis instance-id Example: Enables IS-IS routing for the specified routing instance, and places the router in router configuration mode. • RP/0/RP0/CPU0:router(config)# router isis isp Step 3 log adjacency changes You can change the level of routing to be performed by a particular routing instance using the is-type command. Generates a log message when an IS-IS adjacency changes state (up or down). Example: RP/0/RP0/CPU0:router(config-isis)# log adjacency changes Step 4 interface type number Enters interface configuration mode. Example: RP/0/RP0/CPU0:router(config-isis)# interface POS 0/1/0/3 Step 5 hello-padding {disable | sometimes} [level {1 | 2}] Configures padding on IS-IS hello PDUs for all IS-IS interfaces on the router. • Example: Hello padding applies to only this interface and not to all interfaces. RP/0/RP0/CPU0:router(config-isis-if)# hello-paddi ng sometimes Step 6 hello-interval seconds [level {1 | 2}] Specifies the length of time between hello packets that the software sends. Example: RP/0/RP0/CPU0:router(config-isis-if)# hello-interval 6 Step 7 hello-multiplier multiplier [level {1 | 2}] Example: RP/0/RP0/CPU0:router(config-isis-if)# hello-multiplier 10 Cisco IOS XR Routing Configuration Guide RC-114 Specifies the number of IS-IS hello packets a neighbor must miss before the router should declare the adjacency as down. • A higher value increases the networks tolerance for dropped packets, but also may increase the amount of time required to detect the failure of an adjacent router. • Conversely, not detecting the failure of an adjacent router can result in greater packet loss. Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Step 8 Command or Action Purpose hello-password {hmac-md5 | text} {clear | encrypted} password [level {1 | 2}] [send-only] Specifies that this system include authentication in the hello packets and requires successful authentication of the hello packet from the neighbor to establish an adjacency. Example: RP/0/RP0/CPU1:router(config-isis-if)# hello-password text clear mypassword Step 9 end or Saves configuration changes. commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-isis-if)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-isis-if)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Step 10 show isis [instance instance-id] adjacency [interface-type interface-instance] [detail] [systemid system-id] Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. (Optional) Displays IS-IS adjacencies. Example: RP/0/RP0/CPU0:router# show isis instance isp adjacency ipv4 Step 11 show isis adjacency-log (Optional) Displays a log of the most recent adjacency state transitions. Example: RP/0/RP0/CPU1:router# show isis adjacency-log Cisco IOS XR Routing Configuration Guide RC-115 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Step 12 Command or Action Purpose show isis [instance instance-id] interface [type instance] [brief | detail] [level {1 | 2}] (Optional) Displays information about the IS-IS interface. Example: RP/0/RP0/CPU0:router# show isis interface POS 0/1/0/1 brief Step 13 show isis [instance instance-id] neighbors [interface-type interface-instance] [summary] [detail] [systemid system-id] (Optional) Displays information about IS-IS neighbors. Example: RP/0/RP0/CPU0:router# show isis neighbors summary Setting SPF Interval for a Single-Topology IPv4 and IPv6 Configuration This task explains how to make adjustments to the SPF calculation to tune router performance. This task is optional. Because the SPF calculation computes routes for a particular topology, the tuning attributes are located in the router address family configuration submode. SPF calculation computes routes for Level 1 and Level 2 separately. When IPv4 and IPv6 address families are used in a single-topology mode, only a single SPF for the IPv4 topology exists. The IPv6 topology “borrows” the IPv4 topology; therefore, no SPF calculation is required for IPv6. To tune the SPF calculation parameters for single-topology mode, configure the address-family ipv4 unicast command. The incremental SPF algorithm can be enabled separately. When enabled, the incremental shortest path first (ISPF) is not employed immediately. Instead, the full SPF algorithm is used to “seed” the state information required for the ISPF to run. The startup delay prevents the ISPF from running for a specified interval after an IS-IS restart (to permit the database to stabilize). After the startup delay elapses, the ISPF is principally responsible for performing all of the SPF calculations. The reseed interval enables a periodic running of the full SPF to ensure that the iSFP state remains synchronized. SUMMARY STEPS 1. configure 2. router isis instance-id 3. address-family {ipv4 | ipv6} [unicast] 4. spf-interval {[initial-wait initial | secondary-wait secondary | maximum-wait maximum] ...}[level {1 | 2}] 5. ispf [startup-delay seconds] [level {1 | 2}] 6. ispf startup-delay seconds [level {1 | 2}] 7. end or commit 8. show isis [instance instance-id] spf-log [level {1 | 2}] [ipv4 | ipv6] [unicast] [ispf | fspf | prc] [detail] [internal] [last number | first number] Cisco IOS XR Routing Configuration Guide RC-116 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router isis instance-id Example: Enables IS-IS routing for the specified routing instance, and places the router in router configuration mode. • RP/0/RP0/CPU0:router(config)# router isis isp Step 3 address-family {ipv4 | ipv6} [unicast] Example: You can change the level of routing to be performed by a particular routing instance using the is-type router configuration command. Specifies the IPv4 or IPv6 address family, and enters router address family configuration mode. • This example specifies the unicast IPv6 address family. RP/0/RP0/CPU0:router(config-isis)# address-family ipv6 unicast Step 4 spf-interval { [initial-wait initial | secondary-wait secondary | maximum-wait maximum] ...} [level {1 | 2}] (Optional) Controls the minimum time between successive SPF calculations. • This value imposes a delay in the SPF computation after an event trigger and enforces a minimum elapsed time between SPF runs. • If this value is configured too low, the router can lose too many CPU resources when the network is unstable. • Configuring the value too high delays changes in the network topology that result in lost packets. • The SPF interval does not apply to the running of the ISPF because that algorithm runs immediately on receiving a changed LSP. Example: RP/0/RP0/CPU0:router(config-isis-af)# spf-interval initial-wait 10 maximum-wait 30 Step 5 ispf [startup-delay seconds] [level {1 | 2}] (Optional) Configures incremental IS-IS ISPF to calculate network topology. Example: RP/0/RP0/CPU0:router(config-isis-af)# ispf Step 6 ispf startup-delay seconds [level {1 | 2}] (Optional) Configures the time delay between the starting of the IS-IS instance and the activation of ISPF. Example: RP/0/RP0/CPU0:router(config-isis-af)# ispf startup-delay 600 Cisco IOS XR Routing Configuration Guide RC-117 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Step 7 Command or Action Purpose end Saves configuration changes. or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-isis-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-isis-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Step 8 show isis [ instance instance-id] spf-log [level {1 | 2}] [ipv4 | ipv6] [unicast] [ispf | fspf | prc] [detail] [internal] [last number | first number] Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. (Optional) Displays how often and why the router has run a full SPF calculation. Example: RP/0/RP0/CPU0:router# show isis instance 1 spf-log ipv4 Enabling Multicast-Intact for IS-IS This optional task describes how to enable multicast-intact for IS-IS routes that use IPv4 addresses. Summary Steps 1. configure 2. router isis instance-id 3. address-family {ipv4 | ipv6} [unicast] 4. mpls traffic-eng multicast-intact 5. end or commit Cisco IOS XR Routing Configuration Guide RC-118 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router isis instance-id Example: Enables IS-IS routing for the specified routing process, and places the router in router configuration mode. In this example, the IS-IS instance is called isp. RP/0/RP0/CPU0:router(config)# router isis isp Step 3 address-family {ipv4 | ipv6} [unicast] Example: Specifies the IPv4 or IPv6 address family, and enters router address family configuration mode. This example specifies the unicast IPv4 address family. RP/0/RP0/CPU0:router(config-isis)# address-family ipv4 Step 4 mpls traffic-eng multicast-intact Enables multicast-intact. Example: RP/0/RP0/CPU0:router(config-isis)# mpls traffic-eng multicast-intact Step 5 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-isis-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-isis-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Customizing Routes for IS-IS This task describes how to perform route functions that include injecting default routes into your IS-IS routing domain and redistributing routes learned at one IS-IS level into a different level. This task is optional. Cisco IOS XR Routing Configuration Guide RC-119 Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software SUMMARY STEPS 1. configure 2. router isis instance-id 3. set-overload-bit [on-startup {delay | wait-for-bgp}] [level {1 | 2}] 4. address-family {ipv4 | ipv6} [unicast] 5. default-information originate [route-map map-name] 6. redistribute isis instance [level-1 | level-2 | level-1-2] [metric metric] [metric-type {internal | external}] policy policy-name] 7. summary-prefix [address/prefix-length] [level {1 | 2}] or summary-prefix [ipv6-prefix/prefix-length] [level {1 | 2}] 8. maximum-paths route-number 9. distance weight [address/prefix-length [route-list-name]] 10. set-attached-bit 11. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router isis instance-id Example: Enables IS-IS routing for the specified routing process, and places the router in router configuration mode. • RP/0/RP0/CPU0:router(config)# router isis isp Step 3 set-overload-bit [ on-startup {delay | wait-for-bgp}] [level {1 | 2}] By default, all IS-IS instances are automatically Level 1 and Level 2. You can change the level of routing to be performed by a particular routing instance using the is-type command. (Optional) Sets the overload bit. Note Example: The configured overload bit behavior does not apply to NSF restarts because the NSF restart does not set the overload bit during restart. RP/0/RP0/CPU0:router(config-isis)# set-overload-bit Step 4 address-family {ipv4 | ipv6} [unicast] Example: RP/0/RP0/CPU0:router(config-isis)# address-family ipv6 unicast Cisco IOS XR Routing Configuration Guide RC-120 Specifies the IPv4 or IPv6 address family, and enters router address family configuration mode. • This example specifies the unicast IPv6 address family. Implementing IS-IS on Cisco IOS XR Software How to Implement IS-IS on Cisco IOS XR Software Step 5 Command or Action Purpose default-information originate [route-map map-name] (Optional) Injects a default IPv4 or IPv6 route into an IS-IS routing domain. • The route-map keyword and map-name argument specify the conditions under which the IPv4 or IPv6 default route is advertised. • If the route-map keyword is omitted, then the IPv4 or IPv6 default route is unconditionally advertised at Level 2. Example: RP/0/RP0/CPU0:router(config-isis-af)# default-information originate Step 6 redistribute isis instance [level-1 | level-2 | level-1-2] [metric metric] [metric-type {internal | external}] [policy policy-name] (Optional) Redistributes routes from one IS-IS instance into another instance. • Example: In this example, an IS-IS instance redistributes IS-IS instance 2 routes into its Level 1 area. RP/0/RP0/CPU0:router(config-isis-af)# redistribute isis 2 level-1 Step 7 summary-prefix [address/prefix-length] [level {1 | 2}] or summary-prefix [ipv6-prefix/prefix-length] [level {1 | 2}] Example: RP/0/RP0/CPU0:router(config-isis-af)# summary-prefix 10.1.0.0/16 level 1 (Optional) Allows a Level 1-2 router to summarize Level 1 IPv4 and IPv6 prefixes at Level 2, instead of advertising the Level 1 prefixes directly when the router advertises the summary. • or • This example specifies an IPv6 prefix, and the command must be in the form documented in RFC 2373 in which the address is specified in hexadecimal using 16-bit values between colons. • Note that IPv6 prefixes must be configured only in the IPv6 router address family configuration submode, and IPv4 prefixes in the IPv4 router address family configuration submode. or RP/0/RP0/CPU0:router(config-isis-af)# summary-prefix 3003:xxxx::/24 level 1 Step 8 maximum-paths route-number This example specifies an IPv4 address and mask. (Optional) Configures the maximum number of parallel paths allowed in a routing table. Example: RP/0/RP0/CPU0:router(config-isis-af)# maximum-paths 16 Step 9 distance weight [address/prefix-length [route-list-name]] (Optional) Defines the administrative distance assigned to routes discovered by the IS-IS protocol. • Example: A different administrative distance may be applied for IPv4 and IPv6. RP/0/RP0/CPU0:router(config-isis-af)# distance 90 Cisco IOS XR Routing Configuration Guide RC-121 Implementing IS-IS on Cisco IOS XR Software Configuration Examples for Implementing IS-IS on Cisco IOS XR Software Step 10 Command or Action Purpose set-attached-bit (Optional) Configures an IS-IS instance with an attached bit in the Level 1 LSP. Example: RP/0/RP0/CPU0:router(config-isis-af)# set-attached-bit Step 11 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-isis-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-isis-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Configuration Examples for Implementing IS-IS on Cisco IOS XR Software This section provides the following configuration examples: • Configuring Single-Topology IS-IS for IPv6: Example, page RC-122 • Configuring Multitopology IS-IS for IPv6: Example, page RC-123 • Redistributing IS-IS Routes Between Multiple Instances: Example, page RC-123 Configuring Single-Topology IS-IS for IPv6: Example The following example shows single-topology mode being enabled, an IS-IS instance being created, the NET being defined, IPv6 being configured along with IPv4 on an interface, and IPv4 link topology being used for IPv6. This configuration allows POS interface 0/3/0/0 to form adjacencies for both IPv4 and IPv6 addresses. router isis isp net 49.0000.0000.0001.00 address-family ipv6 unicast single-topology interface POS0/3/0/0 Cisco IOS XR Routing Configuration Guide RC-122 Implementing IS-IS on Cisco IOS XR Software Configuration Examples for Implementing IS-IS on Cisco IOS XR Software address-family ipv4 unicast ! address-family ipv6 unicast ! exit ! interface POS0/3/0/0 ipv4 address 10.0.1.3 255.255.255.0 ipv6 address 2001::1/64 Configuring Multitopology IS-IS for IPv6: Example The following example shows multitopology IS-IS being configured in IPv6. You need not enable IS-IS for IPv6 globally on the router. router isis isp net 49.0000.0000.0001.00 interface POS0/3/0/0 address-family ipv6 unicast metric-style wide level 1 exit ! interface POS0/3/0/0 ipv6 address 2001::1/64 Redistributing IS-IS Routes Between Multiple Instances: Example The following example shows the attached bit being set for a Level 1 instance. This example shows the other Level 1 routers in the area being informed that this router is a suitable candidate to get from the area to the backbone. The Level 1 instance is also propagating routes to the Level 2 instance using redistribution. Note that the administrative distance is explicitly configured higher on the Level 2 instance to ensure that Level 1 routes are preferred. router isis 1 is-type level-2-only net 49.0001.0001.0001.0001.00 address-family ipv4 unicast distance 116 redistribute isis 2 level 2 ! interface POS0/3/0/0 address-family ipv4 unicast ! ! router isis 2 is-type level-1 net 49.0002.0001.0001.0002.00 address-family ipv4 unicast set-attached-bit ! interface POS0/1/0/0 address-family ipv4 unicast Cisco IOS XR Routing Configuration Guide RC-123 Implementing IS-IS on Cisco IOS XR Software Where to Go Next Where to Go Next To implement more IP routing protocols, see the following document modules: • Implementing OSPF on Cisco IOS XR Software • Implementing BGP on Cisco IOS XR Software Additional References The following sections provide references related to implementing IS-IS on Cisco IOS XR software. Related Documents Related Topic Document Title IS-IS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples Cisco IOS XR Routing Command Reference, Release 3.2 MPLS TE feature information Implementing MPLS Traffic Engineering on Cisco IOS XR Software module in the Cisco IOS XR Multiprotocol Label Switching Configuration Guide, Release 3.2 Standards Standards Title Draft-ietf-isis-ipv6-05.txt Routing IPv6 with IS-IS, by Christian E. Hopps Draft-ietf-isis-wg-multi-topology-06.txt M-ISIS: Multi Topology (MT) Routing in IS-IS, by Tony Przygienda, Naiming Shen, and Nischal Sheth Draft-ietf-isis-traffic-05.txt IS-IS Extensions for Traffic Engineering, by Henk Smit and Toni Li Draft-ietf-isis-restart-04.txt Restart Signalling for IS-IS, by M. Shand and Les Ginsberg Draft-ietf-isis-igp-p2p-over-lan-05.txt Point-to-point operation over LAN in link-state routing protocols, by Naiming Shen MIBs MIBs MIBs Link There are no applicable MIBs for this module. To locate and download MIBs for selected platforms using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL: http://cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml Cisco IOS XR Routing Configuration Guide RC-124 Implementing IS-IS on Cisco IOS XR Software Additional References RFCs RFCs Title RFC 1142 OSI IS-IS Intra-domain Routing Protocol RFC 1195 Use of OSI IS-IS for Routing in TCP/IP and Dual Environments RFC 2763 Dynamic Hostname Exchange Mechanism for IS-IS RFC 2966 Domain-wide Prefix Distribution with Two-Level IS-IS RFC 2973 IS-IS Mesh Groups RFC 3277 IS-IS Transient Blackhole Avoidance RFC 3373 Three-Way Handshake for IS-IS Point-to-Point Adjacencies RFC 3567 IS-IS Cryptographic Authentication Technical Assistance Description Link http://www.cisco.com/techsupport The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content. Cisco IOS XR Routing Configuration Guide RC-125 Implementing IS-IS on Cisco IOS XR Software Additional References Cisco IOS XR Routing Configuration Guide RC-126 Implementing OSPF on Cisco IOS XR Software Open Shortest Path First (OSPF) is an Interior Gateway Protocol (IGP) developed by the OSPF working group of the Internet Engineering Task Force (IETF). Designed expressly for IP networks, OSPF supports IP subnetting and tagging of externally derived routing information. OSPF also allows packet authentication and uses IP multicast when sending and receiving packets. Implementing OSPF version 3 (OSPFv3) expands on OSPF Version 2, to provide support for IPv6 routing prefixes. This module describes the concepts and tasks you need to implement both versions of OSPF on your Cisco IOS XR router. The term “OSPF” implies both versions of the routing protocol, unless otherwise noted. Note For more information about OSPF on the Cisco IOS XR software and complete descriptions of the OSPF commands listed in this module, see the “Related Documents” section of this module. To locate documentation for other commands that might appear during execution of a configuration task, search online in the Cisco IOS XR software master command index. Feature History for Implementing OSPF on Cisco IOS XR Software Release Modification Release 2.0 This feature was introduced on the Cisco CRS-1. Release 3.0 No modification. Release 3.2 Support was added for the Cisco XR 12000 Series Router. Release 3.2.2 Support was added for the multicast-intact feature. Contents • Prerequisites for Implementing OSPF on Cisco IOS XR Software, page RC-128 • Information About Implementing OSPF on Cisco IOS XR Software, page RC-128 • How to Implement OSPF on Cisco IOS XR Software, page RC-144 • Configuration Examples for Implementing OSPF on Cisco IOS XR Software, page RC-187 • Where to Go Next, page RC-192 • Additional References, page RC-193 Cisco IOS XR Routing Configuration Guide RC-127 Implementing OSPF on Cisco IOS XR Software Prerequisites for Implementing OSPF on Cisco IOS XR Software Prerequisites for Implementing OSPF on Cisco IOS XR Software The following are prerequisites for implementing OSPF on Cisco IOS XR Software: • You must be in a user group associated with a task group that includes the proper task IDs for OSPF commands. Task IDs for commands are listed in the Cisco IOS XR Task ID Reference Guide. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide. • Configuration tasks for OSPFv3 assume that you are familiar with IPv6 addressing and basic configuration. See the Implementing Network Stack IPv4 and IPv6 on Cisco IOS XR Software module of the Cisco IOS XR IP Addresses and Services Configuration Guide for information on IPv6 routing and addressing. • Before you enable OSPFv3 on an interface, you must perform the following tasks: – Complete the OSPF network strategy and planning for your IPv6 network. For example, you must decide whether multiple areas are required. – Enable IPv6 on the interface. • Configuring authentication (IP Security) is an optional task. If you choose to configure authentication, you must first decide whether to configure plain text or Message Digest 5 (MD5) authentication, and whether the authentication applies to an entire area or specific interfaces. Information About Implementing OSPF on Cisco IOS XR Software To implement OSPF you need to understand the following concepts: • OSPF Functional Overview, page RC-129 • Key Features Supported in the Cisco IOS XR OSPF Implementation, page RC-130 • Comparison of Cisco IOS XR OSPFv3 and OSPFv2, page RC-131 • Importing Addresses into OSPFv3, page RC-131 • OSPF Hierarchical CLI and CLI Inheritance, page RC-131 • OSPF Routing Components, page RC-132 • OSPF Process and Router ID, page RC-134 • Supported OSPF Network Types, page RC-135 • Route Authentication Methods for OSPF Version 2, page RC-135 • Neighbors and Adjacency for OSPF, page RC-136 • Designated Router (DR) for OSPF, page RC-136 • Default Route for OSPF, page RC-137 • Link-State Advertisement Types for OSPF Version 2, page RC-137 • Link-State Advertisement Types for OSPFv3, page RC-137 • Virtual Link and Transit Area for OSPF, page RC-138 • Route Redistribution for OSPF, page RC-139 • OSPF Shortest Path First Throttling, page RC-139 Cisco IOS XR Routing Configuration Guide RC-128 Implementing OSPF on Cisco IOS XR Software Information About Implementing OSPF on Cisco IOS XR Software • Nonstop Forwarding for OSPF Version 2, page RC-140 • Load Balancing in OSPF Version 2 and OSPFv3, page RC-141 OSPF Functional Overview OSPF is a routing protocol for IP. It is a link-state protocol, as opposed to a distance-vector protocol. A link-state protocol makes its routing decisions based on the states of the links that connect source and destination machines. The state of the link is a description of that interface and its relationship to its neighboring networking devices. The interface information includes the IP address of the interface, network mask, type of network to which it is connected, routers connected to that network, and so on. This information is propagated in various types of link-state advertisements (LSAs). A router stores the collection of received link-state advertisement (LSA) data in a link-state database. This database includes LSA data for the links of the router. The contents of the database, when subjected to the Dijkstra algorithm, extract data to create an OSPF routing table. The difference between the database and the routing table is that the database contains a complete collection of raw data; the routing table contains a list of shortest paths to known destinations through specific router interface ports. OSPF is the IGP of choice because it scales to large networks. It uses areas to partition the network into more manageable sizes and to introduce hierarchy in the network. A router is attached to one or more areas in a network. All of the networking devices in an area maintain the same complete database information about the link states in their area only. They do not know about all link states in the network. The agreement of the database information among the routers in the area is called convergence. At the intradomain level, OSPF can import routes learned using Intermediate System-to-Intermediate System (IS-IS). OSPF routes can also be exported into IS-IS. At the interdomain level, OSPF can import routes learned using Border Gateway Protocol (BGP). OSPF routes can be exported into BGP. Unlike Routing Information Protocol (RIP), OSPF does not provide periodic routing updates. On becoming neighbors, OSPF routers establish an adjacency by exchanging and synchronizing their databases. After that, only changed routing information is propagated. Every router in an area advertises the costs and states of its links, sending this information in an LSA. This state information is sent to all OSPF neighbors one hop away. All the OSPF neighbors, in turn, send the state information unchanged. This flooding process continues until all devices in the area have the same link-state database. To determine the best route to a destination, the software sums all of the costs of the links in a route to a destination. After each router has received routing information from the other networking devices, it runs the shortest path first (SPF) algorithm to calculate the best path to each destination network in the database. The networking devices running OSPF detect topological changes in the network, flood link-state updates to neighbors, and quickly converge on a new view of the topology. Each OSPF router in the network soon has the same topological view again. OSPF allows multiple equal-cost paths to the same destination. Since all link-state information is flooded and used in the SPF calculation, multiple equal cost paths can be computed and used for routing. On broadcast and nonbroadcast multiaccess (NBMA) networks, the designated router (DR) or backup DR performs the LSA flooding. On point-to-point networks, flooding simply exits an interface directly to a neighbor. OSPF runs directly on top of IP; it does not use TCP or User Datagram Protocol (UDP). OSPF performs its own error correction by means of checksums in its packet header and LSAs. In OSPFv3, the fundamental concepts are the same as OSPF Version 2, except that support is added for the increased address size of IPv6. New LSA types are created to carry IPv6 addresses and prefixes, and the protocol runs on an individual link basis rather than on an individual IP-subnet basis. Cisco IOS XR Routing Configuration Guide RC-129 Implementing OSPF on Cisco IOS XR Software Information About Implementing OSPF on Cisco IOS XR Software OSPF typically requires coordination among many internal routers: Area Border Routers (ABRs), which are routers attached to multiple areas, and Autonomous System Border Routers (ASBRs) that export reroutes from other sources (for example, IS-IS, BGP, or static routes) into the OSPF topology. At a minimum, OSPF-based routers or access servers can be configured with all default parameter values, no authentication, and interfaces assigned to areas. If you intend to customize your environment, you must ensure coordinated configurations of all routers. Key Features Supported in the Cisco IOS XR OSPF Implementation The Cisco IOS XR implementation of OSPF conforms to the OSPF Version 2 and OSPF Version 3 specifications detailed in the Internet RFC 2328 and RFC 2740, respectively. The following key features are supported in the Cisco IOS XR implementation: • Hierarchy—CLI hierarchy is supported. • Inheritance—CLI inheritance is supported. • Stub areas—Definition of stub areas is supported. • NSF—Nonstop forwarding is supported. • SPF throttling—Shortest path first throttling feature is supported. • LSA throttling—LSA throttling feature is supported. • Fast convergence—SPF and LSA throttle timers are set, configuring fast convergence. The OSPF LSA throttling feature provides a dynamic mechanism to slow down LSA updates in OSPF during network instability. LSA throttling also allows faster OSPF convergence by providing LSA rate limiting in milliseconds. • Route redistribution—Routes learned using any IP routing protocol can be redistributed into any other IP routing protocol. • Authentication—Plain text and MD5 authentication among neighboring routers within an area is supported. • Routing interface parameters—Configurable parameters supported include interface output cost, retransmission interval, interface transmit delay, router priority, router “dead” and hello intervals, and authentication key. • Virtual links—Virtual links are supported. • Not-so-stubby area (NSSA)—RFC 1587 is supported. • OSPF over demand circuit—RFC 1793 is supported. Cisco IOS XR Routing Configuration Guide RC-130 Implementing OSPF on Cisco IOS XR Software Information About Implementing OSPF on Cisco IOS XR Software Comparison of Cisco IOS XR OSPFv3 and OSPFv2 Much of the OSPFv3 protocol is the same as in OSPFv2. OSPFv3 is described in RFC 2740. The key differences between the Cisco IOS XR OSPFv3 and OSPFv2 protocols are as follows: • OSPFv3 expands on OSPFv2 to provide support for IPv6 routing prefixes and the larger size of IPv6 addresses. • When using an NBMA interface in OSPFv3, users must manually configure the router with the list of neighbors. Neighboring routers are identified by the link local address of the attached interface of the neighbor. • Unlike in OSPFv2, multiple OSPFv3 processes can be run on a link. • LSAs in OSPFv3 are expressed as “prefix and prefix length” instead of “address and mask.” • The router ID is a 32-bit number with no relationship to an IPv6 address. Importing Addresses into OSPFv3 When importing into OSPFv3 the set of addresses configured on an OSPFv3 interface, users cannot select specific addresses to be imported. Either all addresses are imported or no addresses are imported. OSPF Hierarchical CLI and CLI Inheritance Cisco IOS XR software introduces new OSPF configuration fundamentals consisting of hierarchical CLI and CLI inheritance. Hierarchical CLI is the grouping of related network component information at defined hierarchical levels such as at the router, area, and interface levels. Hierarchical CLI allows for easier configuration, maintenance, and troubleshooting of OSPF configurations. When configuration commands are displayed together in their hierarchical context, visual inspections are simplified. Hierarchical CLI is intrinsic for CLI inheritance to be supported. With CLI inheritance support, you need not explicitly configure a parameter for an area or interface. In Cisco IOS XR, the parameters of interfaces in the same area can be exclusively configured with a single command, or parameter values can be inherited from a higher hierarchical level—such as from the area configuration level or the router ospf configuration levels. For example, the hello interval value for an interface is determined by this precedence “IF” statement: If the hello interval command is configured at the interface configuration level, then use the interface configured value, else If the hello interval command is configured at the area configuration level, then use the area configured value, else If the hello interval command is configured at the router ospf configuration level, then use the router ospf configured value, else Use the default value of the command. Cisco IOS XR Routing Configuration Guide RC-131 Implementing OSPF on Cisco IOS XR Software Information About Implementing OSPF on Cisco IOS XR Software Tip Understanding hierarchical CLI and CLI inheritance saves you considerable configuration time. See the “Configuring Authentication at Different Hierarchical Levels for OSPF Version 2” section on page RC-155 to understand how to implement these fundamentals. In addition, Cisco IOS XR examples are provided in the “Configuration Examples for Implementing OSPF on Cisco IOS XR Software” section on page RC-187. OSPF Routing Components Before implementing OSPF, you must know what the routing components are and what purpose they serve. They consist of the autonomous system, area types, interior routers, ABRs, and ASBRs. Figure 6 illustrates the routing components in an OSPF network topology. Figure 6 OSPF Routing Components OSPF Domain (BGP autonomous system 109) Area 0 backbone R3 Area 2 stub area Area 1 ABR 2 ABR 1 R1 R2 ASBR 1 Area 3 ASBR 2 88721 OSPF Domain (BGP autonomous system 65200) Autonomous Systems The autonomous system is a collection of networks, under the same administrative control, that share routing information with each other. An autonomous system is also referred to as a routing domain. Figure 6 shows two autonomous systems: A and B. An autonomous system can consist of one or more OSPF areas. Cisco IOS XR Routing Configuration Guide RC-132 Implementing OSPF on Cisco IOS XR Software Information About Implementing OSPF on Cisco IOS XR Software Areas Areas allow the subdivision of an autonomous system into smaller, more manageable networks or sets of adjacent networks. As shown in Figure 6, autonomous system A consists of three areas: Area 0, Area 1, and Area 2. OSPF hides the topology of an area from the rest of the autonomous system. The network topology for an area is visible only to routers inside that area. When OSPF routing is within an area, it is called intra-area routing. This routing limits the amount of link-state information flood into the network, reducing routing traffic. It also reduces the size of the topology information in each router, conserving processing and memory requirements in each router. Also, the routers within an area cannot see the detailed network topology outside the area. Because of this restricted view of topological information, you can control traffic flow between areas and reduce routing traffic when the entire autonomous system is a single routing domain. Backbone Area A backbone area is responsible for distributing routing information between multiple areas of an autonomous system. OSPF routing occurring outside of an area is called interarea routing. The backbone itself has all properties of an area. It consists of ABRs, routers, and networks only on the backbone. As shown in Figure 6, Area 0 is an OSPF backbone area. Any OSPF backbone area has a reserved area ID of 0.0.0.0. Stub Area A stub area is an area that does not accept or detailed network information external to the area. A stub area typically has only one router that interfaces the area to the rest of the autonomous system. The stub ABR advertises a single default route to external destinations into the stub area. Routers within a stub area use this route for destinations outside the area and the autonomous system. This relationship conserves LSA database space that would otherwise be used to store external LSAs flooded into the area. In Figure 6, Area 2 is a stub area that is reached only through ABR 2. Area 0 cannot be a stub area. Not-so-Stubby Area (NSSA) NSSA is similar to the stub area. NSSA does not flood Type 5 external LSAs from the core into the area, but can import autonomous system external routes in a limited fashion within the area. NSSA allows importing of Type 7 autonomous system external routes within an NSSA area by redistribution. These Type 7 LSAs are translated into Type 5 LSAs by NSSA ABRs, which are flooded throughout the whole routing domain. Summarization and filtering are supported during the translation. Use NSSA to simplify administration if you are a network administrator that must connect a central site using OSPF to a remote site that is using a different routing protocol. Before NSSA, the connection between the corporate site border router and remote router could not be run as an OSPF stub area because routes for the remote site could not be redistributed into a stub area, and two routing protocols needed to be maintained. A simple protocol like RIP was usually run and handled the redistribution. With NSSA, you can extend OSPF to cover the remote connection by defining the area between the corporate router and remote router as an NSSA. Area 0 cannot be an NSSA. Cisco IOS XR Routing Configuration Guide RC-133 Implementing OSPF on Cisco IOS XR Software Information About Implementing OSPF on Cisco IOS XR Software Routers The OSPF network is composed of ABRs, ASBRs, and interior routers. Area Border Routers (ABR) ABRs are routers with multiple interfaces that connect directly to networks in two or more areas. An ABR runs a separate copy of the OSPF algorithm and maintains separate routing data for each area that is attached to, including the backbone area. ABRs also send configuration summaries for their attached areas to the backbone area, which then distributes this information to other OSPF areas in the autonomous system. In Figure 6, there are two ABRs. ABR 1 interfaces Area 1 to the backbone area. ABR 2 interfaces the backbone Area 0 to Area 2, a stub area. Autonomous System Boundary Routers (ASBR) ASBRs provide connectivity from one autonomous system to another system. ASBRs exchange their autonomous system routing information with boundary routers in other autonomous systems. Every router inside an autonomous system knows how to reach the boundary routers for its autonomous system. ASBRs can import external routing information from other protocols like BGP and redistribute them as AS-external (ASE) Type 5 LSAs to the OSPF network. If the Cisco IOS XR router is an ASBR, you can configure it to advertise VIP addresses for content as autonomous system external routes. In this way, ASBRs flood information about external networks to routers within the OSPF network. ASBR routes can be advertised as a Type 1 or Type 2 ASE. The difference between Type 1 and Type 2 is how the cost is calculated. For a Type 2 ASE, only the external cost (metric) is considered when multiple paths to the same destination are compared. For a Type 1 ASE, the combination of the external cost and cost to reach the ASBR is used. Type 2 external cost is the default and is always more costly than an OSPF route and used only if no OSPF route exists. Interior Routers The interior routers (such as R1 in Figure 6) attached to one area (for example, all the interfaces reside in the same area). OSPF Process and Router ID An OSPF process is a logical routing entity running OSPF in a physical router. This logical routing entity should not be confused with the logical routing feature that allows a system administrator (known as the Cisco IOS XR Owner) to partition the physical box into separate routers. A physical router can run multiple OSPF processes, although the only reason to do so would be to connect two or more OSPF domains. Each process has its own link-state database. The routes in the routing table are calculated from the link-state database. One OSPF process does not share routes with another OSPF process unless the routes are redistributed. Each OSPF process is identified by a router ID. The router ID must be unique across the entire routing domain. OSPFv2 obtains a router ID from the following sources, in order of decreasing preference: OSPF attempts to obtain a router ID in the following ways (in order of preference): • The 32-bit numeric value specified by the OSPF router-id command in router configuration mode. (This value can be any 32-bit value. It is not restricted to the IPv4 addresses assigned to interfaces on this router, and need not be a routable IPv4 address.) Cisco IOS XR Routing Configuration Guide RC-134 Implementing OSPF on Cisco IOS XR Software Information About Implementing OSPF on Cisco IOS XR Software • The primary IPv4 address of the interface specified by the OSPF router-id command. • The 32-bit numeric value specified by the router-id command in global configuration mode. (This value must be an IPv4 address assigned to an interface on this router.) • By using the highest IPv4 address on a loopback interface in the system if the router is booted with saved loopback address configuration. • The primary IPv4 address of an interface over which this OSPF process is running. We recommend that the router ID be set by the router-id command in router configuration mode. Separate OSPF processes could share the same router ID, in which case they cannot reside in the same OSPF routing domain. Supported OSPF Network Types OSPF classifies different media into the following three types of networks by default: • NBMA networks (POS) • Point-to-point networks (POS) • Broadcast networks (Gigabit Ethernet) You can configure your Cisco IOS XR network as either a broadcast or an NBMA network. Using this feature, you can configure broadcast networks as NBMA networks when, for example, you have routers in your network that do not support multicast addressing. Route Authentication Methods for OSPF Version 2 OSPF Version 2 supports two types of route authentication: plain text authentication and MD5 authentication. By default, no authentication is enabled (referred to as null authentication in RFC 2178). Both plain text and MD5 authentication are performed on changed routing information that arrive on an interface. The sender and receiver must know the authentication password or key. For both types of authentication, a router sends a routing update packet with a key and corresponding key number. The receiving router checks the key number and key against its own stored key number and key. If the key numbers and keys match, the router accepts the routing update packet. If they do not match, the routing update is discarded. Plain Text Authentication Plain text authentication (also known as Type 1 authentication) uses a password that travels on the physical medium and is easily visible to someone that does not have access permission and could use the password to infiltrate a network. Therefore, plain text authentication does not provide security. It might protect against a faulty implementation of OSPF or a misconfigured OSPF interface trying to send erroneous OSPF packets. MD5 Authentication MD5 authentication provides a means of security. No password travels on the physical medium. Instead, the router uses MD5 to produce a message digest of the OSPF packet plus the key, which is sent on the physical medium. Using MD5 authentication prevents a router from accepting unauthorized or deliberately malicious routing updates, which could compromise your network security by diverting your traffic. Cisco IOS XR Routing Configuration Guide RC-135 Implementing OSPF on Cisco IOS XR Software Information About Implementing OSPF on Cisco IOS XR Software Note MD5 authentication supports multiple keys, requiring that a key number be associated with a key. Authentication Strategies Authentication can be specified for an entire process or area, or on an interface or a virtual link. An interface or virtual link can be configured for only one type of authentication, not both. Authentication configured for an interface or virtual link overrides authentication configured for the area or process. If you intend for all interfaces in an area to use the same type of authentication, you can configure fewer commands if you use the area authentication command (and specify the message-digest keyword if you want the entire area to use MD5 authentication). This strategy requires fewer commands than specifying authentication for each interface. Key Rollover To support the changing of a plain text key or MD5 key in an operational network without disrupting OSPF adjacencies (and hence the topology), a key rollover mechanism is supported. As a network administrator configures the new key into the multiple networking devices that communicate, some time exists when different devices are using both a new key and an old key. If an interface is configured with a new key, the software sends two copies of the same packet, each authenticated by the old key and new key. The software tracks which devices start using the new key, and the software stops sending duplicate packets after it detects that all of its neighbors are using the new key. The software then discards the old key. The network administrator must then remove the old key from each the configuration file of each router. Neighbors and Adjacency for OSPF Routers that share a segment (Layer 2 link between two interfaces) become neighbors on that segment. OSPF uses the hello protocol as a neighbor discovery and keep alive mechanism. The hello protocol involves receiving and periodically sending hello packets out each interface. The hello packets list all known OSPF neighbors on the interface. Routers become neighbors when they see themselves listed in the hello packet of the neighbor. After two routers are neighbors, they may proceed to exchange and synchronize their databases, which creates an adjacency. On broadcast and NBMA networks all neighboring routers have an adjacency. Designated Router (DR) for OSPF On point-to-point and point-to-multipoint networks, the Cisco IOS XR software floods routing updates to immediate neighbors. No DR or backup DR (BDR) exists; all routing information is flooded to each router. On broadcast or NBMA segments only, OSPF minimizes the amount of information being exchanged on a segment by choosing one router to be a DR and one router to be a BDR. Thus, the routers on the segment have a central point of contact for information exchange. Instead of each router exchanging routing updates with every other router on the segment, each router exchanges information with the DR and BDR. The DR and BDR relay the information to the other routers. On broadcast network segments the number of OSPF packets is further reduced by the DR and BDR sending such OSPF updates to a multicast IP address that all OSPF routers on the network segment are listening on. Cisco IOS XR Routing Configuration Guide RC-136 Implementing OSPF on Cisco IOS XR Software Information About Implementing OSPF on Cisco IOS XR Software The software looks at the priority of the routers on the segment to determine which routers are the DR and BDR. The router with the highest priority is elected the DR. If there is a tie, then the router with the higher router ID takes precedence. After the DR is elected, the BDR is elected the same way. A router with a router priority set to zero is ineligible to become the DR or BDR. Default Route for OSPF Type 5 (ASE) LSAs are generated and flooded to all areas except stub areas. For the routers in a stub area to be able to route packets to destinations outside the stub area, a default route is injected by the ABR attached to the stub area. The cost of the default route is 1 (default) or is determined by the value specified in the default-cost command. Link-State Advertisement Types for OSPF Version 2 Each of the following LSA types has a different purpose: • Router LSA (Type 1)—Describes the links that the router has within a single area, and the cost of each link. These LSAs are flooded within an area only. The LSA indicates if the router can compute paths based on quality of service (QoS), whether it is an ABR or ASBR, and if it is one end of a virtual link. Type 1 LSAs are also used to advertise stub networks. • Network LSA (Type 2)—Describes the link state and cost information for all routers attached a multiaccess network segment. This LSA lists all the routers that have interfaces attached to the network segment. It is the job of the designated router of a network segment to generate and track the contents of this LSA. • Summary LSA for ABRs (Type 3)—Advertises internal networks to routers in other areas (interarea routes). Type 3 LSAs may represent a single network or a set of networks aggregated into one prefix. Only ABRs generate summary LSAs. • Summary LSA for ASBRs (Type 4)—Advertises and ASBR and the cost to reach it. Routers that are trying to reach an external network use these advertisements to determine the best path to the next hop. ABRs generate Type 4 LSAs. • Autonomous system external LSA (Type 5)—Redistributes routes from another autonomous system, usually from a different routing protocol into OSPF. Link-State Advertisement Types for OSPFv3 Each of the following LSA types has a different purpose: • Router LSA (Type 1)—Describes the link state and costs of a the router link to the area. These LSAs are flooded within an area only. The LSA indicates whether the router is an ABR or ASBR and if it is one end of a virtual link. Type 1 LSAs are also used to advertise stub networks. In OSPFv3, these LSAs have no address information and are network protocol independent. In OSPFv3, router interface information may be spread across multiple router LSAs. Receivers must concatenate all router LSAs originated by a given router before running the SPF calculation. Cisco IOS XR Routing Configuration Guide RC-137 Implementing OSPF on Cisco IOS XR Software Information About Implementing OSPF on Cisco IOS XR Software • Network LSA (Type 2)—Describes the link state and cost information for all routers attached to a multiaccess network segment. This LSA lists all OSPF routers that have interfaces attached to the network segment. Only the elected designated router for the network segment can generate and track the network LSA for the segment. In OSPFv3, network LSAs have no address information and are network-protocol-independent. • Interarea-prefix LSA for ABRs (Type 3)—Advertises internal networks to routers in other areas (interarea routes). Type 3 LSAs may represent a single network or set of networks aggregated into one prefix. Only ABRs generate Type 3 LSAs. In OSPFv3, addresses for these LSAs are expressed as “prefix and prefix length” instead of “address and mask.” The default route is expressed as a prefix with length 0. • Interarea-router LSA for ASBRs (Type 4)—Advertises an ASBR and the cost to reach it. Routers that are trying to reach an external network use these advertisements to determine the best path to the next hop. ABRs generate Type 4 LSAs. • Autonomous system external LSA (Type 5)—Redistributes routes from another autonomous system, usually from a different routing protocol into OSPF. In OSPFv3, addresses for these LSAs are expressed as “prefix and prefix length” instead of “address and mask.” The default route is expressed as a prefix with length 0. • Link LSA (Type 8)—Has link-local flooding scope and is never flooded beyond the link with which it is associated. Link LSAs provide the link-local address of the router to all other routers attached to the link or network segment, inform other routers attached to the link of a list of IPv6 prefixes to associate with the link, and allow the router to assert a collection of Options bits to associate with the network LSA that is originated for the link. • Intra-area-prefix LSAs (Type 9)—A router can originate multiple intra-area-prefix LSAs for every router or transit network, each with a unique link-state ID. The link-state ID for each intra-area-prefix LSA describes its association to either the router LSA or network LSA and contains prefixes for stub and transit networks. An address prefix occurs in almost all newly defined LSAs. The prefix is represented by three fields: Prefix Length, Prefix Options, and Address Prefix. In OSPFv3, addresses for these LSAs are expressed as “prefix and prefix length” instead of “address and mask.” The default route is expressed as a prefix with length 0. Inter-area-prefix and intra-area-prefix LSAs carry all IPv6 prefix information that, in IPv4, is included in router LSAs and network LSAs. The Options field in certain LSAs (router LSAs, network LSAs, interarea-router LSAs, and link LSAs) has been expanded to 24 bits to provide support for OSPF in IPv6. In OSPFv3, the sole function of link-state ID in interarea-prefix LSAs, interarea-router LSAs, and autonomous system external LSAs is to identify individual pieces of the link-state database. All addresses or router IDs that are expressed by the link-state ID in OSPF Version 2 are carried in the body of the LSA in OSPFv3. Virtual Link and Transit Area for OSPF In OSPF, routing information from all areas is first summarized to the backbone area by ABRs. The same ABRs, in turn, propagate such received information to their attached areas. Such hierarchical distribution of routing information requires that all areas be connected to the backbone area (Area 0). Occasions might exist for which an area must be defined, but it cannot be physically connected to Area 0. Examples of such an occasion might be if your company makes a new acquisition that includes an OSPF area, or if Area 0 itself is partitioned. Cisco IOS XR Routing Configuration Guide RC-138 Implementing OSPF on Cisco IOS XR Software Information About Implementing OSPF on Cisco IOS XR Software In the case in which an area cannot be connected to Area 0, you must configure a virtual link between that area and Area 0. The two endpoints of a virtual link are ABRs, and the virtual link must be configured in both routers. The common nonbackbone area to which the two routers belong is called a transit area. A virtual link specifies the transit area and the router ID of the other virtual endpoint (the other ABR). A virtual link cannot be configured through a stub area or NSSA. Figure 7 illustrates a virtual link from Area 3 to Area 0. Figure 7 Virtual Link to Area 0 OSPF Domain (BGP autonomous system 109) Area 0 Backbone Area 1 ABR 2 ABR 1 Area 3 ABR 3 Transit Area ASBR 1 Router ID 4.4.4.4 88722 Router ID 5.5.5.5 ASBR 2 Route Redistribution for OSPF Redistribution allows different routing protocols to exchange routing information. This technique can be used to allow connectivity to span multiple routing protocols. It is important to remember that the redistribute command controls redistribution into an OSPF process and not from OSPF. See the “Configuration Examples for Implementing OSPF on Cisco IOS XR Software” section on page RC-187 for an example of route redistribution for OSPF. OSPF Shortest Path First Throttling OSPF SPF throttling makes it possible to configure SPF scheduling in millisecond intervals and to potentially delay SPF calculations during network instability. SPF is scheduled to calculate the Shortest Path Tree (SPT) when there is a change in topology. One SPF run may include multiple topology change events. Cisco IOS XR Routing Configuration Guide RC-139 Implementing OSPF on Cisco IOS XR Software Information About Implementing OSPF on Cisco IOS XR Software The interval at which the SPF calculations occur is chosen dynamically and based on the frequency of topology changes in the network. The chosen interval is within the boundary of the user-specified value ranges. If network topology is unstable, SPF throttling calculates SPF scheduling intervals to be longer until topology becomes stable. SPF calculations occur at the interval set by the timers throttle spf command. The wait interval indicates the amount of time to wait until the next SPF calculation occurs. Each wait interval after that calculation is twice as long as the previous interval until the interval reaches the maximum wait time specified. The SPF timing can be better explained using an example. In this example, the start interval is set at 5 milliseconds (ms), initial wait interval at 1000 ms, and maximum wait time at 90,000 ms. timers spf 5 1000 90000 Figure 8 shows the intervals at which the SPF calculations occur as long as at least one topology change event is received in a given wait interval. SPF Calculation Intervals Set by the timers spf Command 5 ms 2000 ms 1000 ms 4000 ms 8000 ms 32000 ms 16000 ms 88278 Figure 8 90000 ms 64000 ms Notice that the wait interval between SPF calculations doubles when at least one topology change event is received during the previous wait interval. After the maximum wait time is reached, the wait interval remains the same until the topology stabilizes and no event is received in that interval. If the first topology change event is received after the current wait interval, the SPF calculation is delayed by the amount of time specified as the start interval. The subsequent wait intervals continue to follow the dynamic pattern. If the first topology change event occurs after the maximum wait interval begins, the SPF calculation is again scheduled at the start interval and subsequent wait intervals are reset according to the parameters specified in the timers throttle spf command. Notice in Figure 9 that a topology change event was received after the start of the maximum wait time interval and that the SPF intervals have been reset. Figure 9 Timer Intervals Reset After Topology Change Event 64000 ms 1000 ms 5 ms 2000 ms 90000 ms 4000 ms 88279 Topology change event 16000 ms 8000 ms 90000 ms SPF scheduled at start interval Nonstop Forwarding for OSPF Version 2 Cisco IOS XR NSF for OSPF Version 2 allows for the forwarding of data packets to continue along known routes while the routing protocol information is being restored following a failover. With NSF, peer networking devices do not experience routing flaps. During failover, data traffic is forwarded Cisco IOS XR Routing Configuration Guide RC-140 Implementing OSPF on Cisco IOS XR Software Information About Implementing OSPF on Cisco IOS XR Software through intelligent line cards while the standby Route Processor (RP) assumes control from the failed RP. The ability of line cards to remain up through a failover and to be kept current with the Forwarding Information Base (FIB) on the active RP is key to Cisco IOS XR NSF operation. Routing protocols, such as OSPF, run only on the active RP or DRP and receive routing updates from their neighbor routers. When an OSPF NSF-capable router performs an RP failover, it must perform two tasks to resynchronize its link-state database with its OSPF neighbors. First, it must relearn the available OSPF neighbors on the network without causing a reset of the neighbor relationship. Second, it must reacquire the contents of the link-state database for the network. As quickly as possible after an RP failover, the NSF-capable router sends an OSPF NSF signal to neighboring NSF-aware devices. This signal is in the form of a link-local LSA generated by the failed-over router. Neighbor networking devices recognize this signal as a cue that the neighbor relationship with this router should not be reset. As the NSF-capable router receives signals from other routers on the network, it can begin to rebuild its neighbor list. After neighbor relationships are re-established, the NSF-capable router begins to resynchronize its database with all of its NSF-aware neighbors. At this point, the routing information is exchanged between the OSPF neighbors. After this exchange is completed, the NSF-capable device uses the routing information to remove stale routes, update the RIB, and update the FIB with the new forwarding information. OSPF on the router as well as the OSPF neighbors are now fully converged. Note The standardized IETF version of NSF, known as OSPF graceful restart (RFC 3623) is also supported. Load Balancing in OSPF Version 2 and OSPFv3 When a router learns multiple routes to a specific network by using multiple routing processes (or routing protocols), it installs the route with the lowest administrative distance in the routing table. Sometimes the router must select a route from among many learned by using the same routing process with the same administrative distance. In this case, the router chooses the path with the lowest cost (or metric) to the destination. Each routing process calculates its cost differently; the costs may need to be manipulated to achieve load balancing. OSPF performs load balancing automatically. If OSPF finds that it can reach a destination through more than one interface and each path has the same cost, it installs each path in the routing table. The only restriction on the number of paths to the same destination is controlled by the maximum-paths (OSPF) command. The default number of maximum paths is 32 for Cisco CRS-1 routers and 16 for Cisco XR 12000 Series Routers. The range is from 1 to 32 for Cisco CRS-1 routers and 1 to 16 for Cisco XR 12000 Series Routers. Graceful Restart for OSPFv3 In the current release, various restart scenarios in the control plane of an IPv6-enabled router can disrupt data forwarding. The OSPFv3 Graceful Restart feature can preserve the data plane capability in the following circumstances: • RP failure, resulting in a switchover to the backup processor • Planned OSPFv3 process restart, such as software upgrade or downgrade • Unplanned OSPFv3 process restart, such as a process crash This feature supports non-stop data forwarding on established routes while the OSPFv3 routing protocol is restarting. (Therefore, this feature enhances high availability of IPv6 forwarding.) Cisco IOS XR Routing Configuration Guide RC-141 Implementing OSPF on Cisco IOS XR Software Information About Implementing OSPF on Cisco IOS XR Software Modes of Graceful Restart Operation The two operational modes that a router can be in for this feature are restart mode and helper mode. Restart mode occurs when the OSPFv3 process is doing a graceful restart. Helper mode refers to the neighbor routers that continue to forward traffic on established OSPFv3 routes while OSPFv3 is restarting on a neighboring router. Restart Mode When the OSPFv3 process starts up, it determines whether it must attempt a graceful restart. The determination is based on whether graceful restart was previously enabled. (OSPFv3 does not attempt a graceful restart upon the first-time startup of the router.) When OSPFv3 graceful restart is enabled, it changes the purge timer in the RIB to a non-zero value. See Configuring OSPFv3 Graceful Restart, page RC-181, for descriptions of how to enable and configure the Graceful Restart feature. During a graceful restart, the router does not populate OSPFv3 routes in the RIB. It tries to bring up full adjacencies with the fully-adjacent neighbors that OSPFv3 had before the restart. Eventually, the OSPFv3 process indicates to the RIB that it has converged either for the purpose of terminating the graceful restart (for any reason) or because it has completed the graceful restart. The following are general details about restart mode. More detailed information on behavior and certain restrictions and requirements appear in the Graceful Restart Requirements and Restrictions section. • If the OSPFv3 attempts a restart too soon after the most recent restart, the OSPFv3 process is most likely crashing repeatedly, so the new graceful restart stops running. To control the period between allowable graceful restarts, use the graceful-restart interval command. A description of how to set this time period appears in the section Configuring the Minimum Time Required Between Restarts, page RC-183. • When OSFPv3 starts a graceful restart with the first interface that comes up, a timer starts running to limit the duration (or lifetime) of the graceful restart. You can configure this period with the graceful-restart lifetime command. On each interface that comes up, a grace LSA (type 11) is flooded to indicate to the neighboring routers that this router is attempting graceful restart. The neighbors enter into helper mode. • The designated router and backup designated router check of the hello packet received from the restarting neighbor is bypassed because it might not be valid. Helper Mode Helper mode is enabled by default. When a (helper) router receives a grace LSA (type 11) from a router that is attempting a graceful restart, the following events occur: • If helper mode has been disabled through the graceful-restart helper disable command, the router drops the LSA packet. • If helper mode is enabled, the router enters helper mode if all of the following conditions are met. – The local router itself is not attempting a graceful restart. – The local (helping) router has full adjacency with the sending neighbor. – The value of lsage (link state age) in the received LSA is less than the requested grace period. – The sender of the grace LSA is the same as the originator of the grace LSA. Cisco IOS XR Routing Configuration Guide RC-142 Implementing OSPF on Cisco IOS XR Software Information About Implementing OSPF on Cisco IOS XR Software • Upon entering helper mode, a router performs its helper function for a specific period of time. This time period is the lifetime value from the router that is in restart mode—minus the value of lsage in the received grace LSA. If the graceful restart succeeds in time, the helper’s timer is stopped before it expires. If the helper’s timer does expire, the adjacency to the restarting router is brought down, and normal OSPFv3 functionality resumes. • The dead timer is not honored by the router that is in helper mode. • A router in helper mode ceases to perform the helper function in any of the following cases: – The helper router is able to bring up a FULL adjacency with the restarting router. – The local timer for the helper function expires. Graceful Restart Requirements and Restrictions The requirements for supporting the Graceful Restart feature include: • Cooperation of a router’s neighbors during a graceful restart. In relation to the router on which OSPFv3 is restarting, each router is called a helper. • All neighbors of the router that does a graceful restart must be capable of doing a graceful restart. • A graceful restart does not occur upon the first-time startup of a router. • OSPFv3 neighbor information and database information are not check-pointed. • An OSPFv3 process rebuilds adjacencies after it restarts. • To ensure consistent databases after a restart, the OSPFv3 configuration must be identical to the configuration before the restart. (This requirement applies to self-originated information in the local database.) A graceful restart can fail if configurations change during the operation. In this case, data forwarding would be affected. OSPFv3 resumes operation by regenerating all its LSAs and resynchronizing its database with all its neighbors. • Although IPv6 FIB tables remain unchanged during a graceful restart, these tables eventually mark the routes as stale through the use of a holddown timer. Enough time is allowed for the protocols to rebuild state information and converge. • The router on which OSPFv3 is restarting must send OSPFv3 hellos within the dead interval of the process restart. Protocols must be able to retain adjacencies with neighbors before the adjacency dead timer expires. The default for the dead timer is 40 seconds. If hellos do not arrive on the adjacency before the dead timer expires, the router takes down the adjacency. The OSPFv3 Graceful Restart feature does not function properly if the dead timer is configured to be less than the time required to send hellos after the OSPFv3 process restarts. • Simultaneous graceful restart sessions on multiple routers are not supported on a single network segment. If a router determines that multiple routers are in restart mode, it terminates any local graceful restart operation. • This feature utilizes the available support for changing the purge time of existing OSPFv3 routes in the routing information base (RIB). When graceful restart is enabled, the purge timer is set to 90 seconds by default. If graceful restart is disabled, the purge timer setting is 0. • This feature has an associated grace LSA. This link-scope LSA is type 11. • According to the RFC, the OSPFv3 process should flush all old, self-originated LSAs during a restart. With the Graceful Restart feature, however, the router delays this flushing of unknown self-originated LSAs during a graceful restart. OSPFv3 can learn new information and build new LSAs to replace the old LSAs. When the delay is over, all old LSAs are flushed. Cisco IOS XR Routing Configuration Guide RC-143 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software • If graceful restart is enabled, the adjacency creation time of all the neighbors is saved in the system database (SysDB). The purpose for saving the creation time is so that OSPFv3 can use the original adjacency creation time to display the uptime for that neighbor after the restart. Multicast-Intact Feature The multicast-intact feature provides the ability to run multicast routing (PIM) when IGP shortcuts are configured and active on the router. Both OSPFv2 and IS-IS support the multicast-intact feature. You can enable multicast-intact in the IGP when multicast routing protocols (PIM) are configured and IGP shortcuts are configured on the router. IGP shortcuts are MPLS tunnels that are exposed to IGP. The IGPs routes IP traffic over these tunnels to destinations that are downstream from the egress router of the tunnel (from an SPF perspective). PIM cannot use IGP shortcuts for propagating PIM joins because reverse path forwarding (RPF) cannot work across a unidirectional tunnel. When you enable multicast-intact on an IGP, the IGP publishes a parallel or alternate set of equal-cost next-hops for use by PIM. These next-hops are called mcast-intact next-hops. The mcast-intact next-hops have the following attributes: • They are guaranteed not to contain any IGP shortcuts. • They are not used for unicast routing but are used only by PIM to look up an IPv4 next-hop to a PIM source. • They are not published to the FIB. • When multicast-intact is enabled on an IGP, all IPv4 destinations that were learned through link-state advertisements are published with a set equal-cost mcast-intact next-hops to the RIB. This attribute applies even when the native next-hops have no IGP shortcuts. • In OSPF, the max-paths (number of equal-cost next-hops) limit is applied separately to the native and mcast-intact next-hops. The number of equal cost mcast-intact next-hops is the same as that configured for the native next-hops. (In IS-IS, the behavior is slightly different.) How to Implement OSPF on Cisco IOS XR Software This section contains the following procedures: • Enabling OSPF, page RC-145 (required) • Configuring Stub and Not-so-Stubby Area Types, page RC-147 (optional) • Configuring Neighbors for Nonbroadcast Networks, page RC-150 (optional) • Configuring Authentication at Different Hierarchical Levels for OSPF Version 2, page RC-155 (optional) • Controlling the Frequency that the Same LSA Is Originated or Accepted for OSPF, page RC-158 (optional) • Creating a Virtual Link with MD5 Authentication to Area 0 for OSPF, page RC-160 (optional) • Summarizing Subnetwork LSAs on an OSPF ABR, page RC-164 (optional) • Redistributing Routes from One IGP into OSPF, page RC-166 (optional) • Configuring OSPF Shortest Path First Throttling, page RC-170 (optional) • Configuring Nonstop Forwarding for OSPF Version 2, page RC-173 (optional) • Configuring OSPF Version 2 for MPLS Traffic Engineering, page RC-175 (optional) Cisco IOS XR Routing Configuration Guide RC-144 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software • Verifying OSPF Configuration and Operation, page RC-180 (optional) • Configuring OSPFv3 Graceful Restart, page RC-181 (optional) • Enabling Multicast-Intact for OSPFv2, page RC-186 (optional) Enabling OSPF This task explains how to perform the minimum OSPF configuration on your router that is to enable an OSPF process with a router ID, configure a backbone or nonbackbone area, and then assign one or more interfaces on which OSPF runs. Prerequisites Although you can configure OSPF before you configure an IP address, no OSPF routing occurs until at least one IP address is configured. SUMMARY STEPS 1. configure 2. router ospf process-name or router ospfv3 process-name 3. router-id {ipv4-address | interface-type interface-instance} 4. area area-id 5. interface type instance 6. Repeat Step 5 for each interface that use OSPF. 7. log adjacency changes [detail] [enable | disable] 8. end or commit Cisco IOS XR Routing Configuration Guide RC-145 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router ospf process-name or router ospfv3 process-name Example: Enables OSPF routing for the specified routing process, and places the router in router configuration mode. or Enables OSPFv3 routing for the specified routing process, and places the router in router ospfv3 configuration mode. RP/0/RP0/CPU0:router(config)# router ospf 1 Note or The process-name argument is any alphanumeric string no longer than 40 characters. RP/0/RP0/CPU0:router(config)# router ospfv3 1 Step 3 router-id {ipv4-address | interface-type interface-instance} Configures a router ID for the OSPF process. Note We recommend using a stable IP address as the router ID. Example: RP/0/RP0/CPU0:router(config-ospf)# router-id 192.168.4.3 Step 4 area area-id Example: RP/0/RP0/CPU0:router(config-ospf)# area 0 Step 5 interface type instance Enters area configuration mode and configures an area for the OSPF process. • Backbone areas have an area ID of 0. • Nonbackbone areas have a nonzero area ID. • The area-id argument can be entered in dotted-decimal or IPv4 address notation, such as area 1000 or area 0.0.3.232. However, you must choose one form or the other for an area. We recommend using the IPv4 address notation. Enters interface configuration mode and associates one or more interfaces for the area configured in Step 4. Example: RP/0/RP0/CPU0:router(config-ospf-ar)# interface POS 0/1/0/3 Step 6 Repeat Step 5 for each interface that uses OSPF. Cisco IOS XR Routing Configuration Guide RC-146 — Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 7 Command or Action Purpose log adjacency changes [detail] [enable | disable] (Optional) Requests notification of neighbor changes. Example: • By default, this feature is enabled. • The messages generated by neighbor changes are considered notifications, which are categorized as severity Level 5 in the logging console command. The logging console command controls which severity level of messages are sent to the console. By default, all severity level messages are sent. RP/0/RP0/CPU0:router(config-ospf-ar-if)# log adjacency changes detail Step 8 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-ospf-ar-if)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-ospf-ar-if)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Configuring Stub and Not-so-Stubby Area Types This task explains how to configure the stub area and the NSSA for OSPF. SUMMARY STEPS 1. configure 2. router ospf process-name or router ospfv3 process-name 3. router-id {ipv4-address | interface-type interface-instance} 4. area area-id 5. stub [no-summary] or nssa [no-redistribution] [default-information-originate] [no-summary] Cisco IOS XR Routing Configuration Guide RC-147 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software 6. stub or nssa 7. default-cost cost 8. end or commit 9. Repeat this task on all other routers in the stub area or NSSA. DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router ospf process-name or router ospfv3 process-name Example: Enables OSPF routing for the specified routing process, and places the router in router configuration mode. or Enables OSPFv3 routing for the specified routing process, and places the router in router ospfv3 configuration mode. RP/0/RP0/CPU0:router(config)# router ospf 1 Note or The process-name argument is any alphanumeric string no longer than 40 characters. RP/0/RP0/CPU0:router(config)# router ospfv3 1 Step 3 router-id {ipv4-address | interface-type interface-instance} Configures a router ID for the OSPF process. Note We recommend using a stable IP address as the router ID. Example: RP/0/RP0/CPU0:router(config-ospf)# router-id 192.168.4.3 Step 4 area area-id Example: RP/0/RP0/CPU0:router(config-ospf)# area 1 Cisco IOS XR Routing Configuration Guide RC-148 Enters area configuration mode and configures a nonbackbone area for the OSPF process. • The area-id argument can be entered in dotted-decimal or IPv4 address notation, such as area 1000 or area 0.0.3.232. However, you must choose one form or the other for an area. We recommend using the IPv4 address notation. Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 5 Command or Action Purpose stub [no-summary] Defines the nonbackbone area as a stub area. or • See the “Configuring Stub and Not-so-Stubby Area Types” section on page RC-147. • Specify the no-summary keyword to further reduce the number of LSAs sent into a stub area. This keyword prevents the ABR from sending summary link-state advertisements (Type 3) in the stub area. nssa [no-redistribution] [default-information-originate] [no-summary] Example: RP/0/RP0/CPU0:router(config-ospf-ar)# stub no summary or or RP/0/RP0/CPU0:router(config-ospf-ar)# nssa no-redistribution Defines an area as an NSSA. • Step 6 stub or nssa (Optional) Turns off the options configured for stub and NSSA areas. • If you configured the stub and NSSA areas using the optional keywords (no-summary, no-redistribution, default-information-originate, and no-summary) in Step 5, you must now reissue the stub and nssa commands without the keywords—rather than using the no form of the command. • For example, the no nssa default-information-originate form of the command changes the NSSA area into a normal area that inadvertently brings down the existing adjacencies in that area. Example: RP/0/RP0/CPU0:router(config-ospf-ar)# stub or RP/0/RP0/CPU0:router(config-ospf-ar)# nssa Step 7 default-cost cost Example: See the “Configuring Stub and Not-so-Stubby Area Types” section on page RC-147. (Optional) Specifies a cost for the default summary route sent into a stub area or an NSSA. • Use this command only on ABRs attached to the NSSA. Do not use it on any other routers in the area. • The default cost is 1. RP/0/RP0/CPU0:router(config-ospf-ar)# default-cost 15 Cisco IOS XR Routing Configuration Guide RC-149 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 8 Command or Action Purpose end Saves configuration changes. or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-ospf-ar)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-ospf-ar)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Step 9 Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Repeat this task on all other routers in the stub area or — NSSA. Configuring Neighbors for Nonbroadcast Networks This task explains how to configure neighbors for a nonbroadcast network. This task is optional. Prerequisites Configuring NBMA networks as either broadcast or nonbroadcast assumes that there are virtual circuits from every router to every other router or a fully meshed network. SUMMARY STEPS 1. configure 2. router ospf process-name or router ospfv3 process-name 3. router-id {ipv4-address | interface-type interface-instance} 4. area area-id 5. network {broadcast | non-broadcast | {point-to-multipoint [non-broadcast] | point-to-point}} 6. dead-interval seconds 7. hello-interval seconds 8. interface type number Cisco IOS XR Routing Configuration Guide RC-150 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software 9. neighbor ip-address [priority number] [poll-interval seconds] [cost number] or neighbor ipv6-link-local-address [priority number] [poll-interval seconds] [cost number] [database-filter [all]] 10. Repeat Step 9 for all neighbors on the interface. 11. exit 12. interface type instance 13. neighbor ip-address [priority number] [poll-interval seconds][cost number] [database-filter [all]] or neighbor ipv6-link-local-address [priority number] [poll-interval seconds][cost number] [database-filter [all]] 14. Repeat Step 13 for all neighbors on the interface. 15. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router ospf process-name or router ospfv3 process-name Example: Enables OSPF routing for the specified routing process, and places the router in router configuration mode. or Enables OSPFv3 routing for the specified routing process, and places the router in router ospfv3 configuration mode. RP/0/RP0/CPU0:router(config)# router ospf 1 or Note The process-name argument is any alphanumeric string no longer than 40 characters. RP/0/RP0/CPU0:router(config)# router ospfv3 1 Step 3 router-id {ipv4-address | interface-type interface-instance} Configures a router ID for the OSPF process. Note We recommend using a stable IP address as the router ID. Example: RP/0/RP0/CPU0:router(config-ospf)# router-id 192.168.4.3 Step 4 area area-id Example: RP/0/RP0/CPU0:router(config-ospf)# area 0 Enters area configuration mode and configures an area for the OSPF process. • This example configures a backbone area. • The area-id argument can be entered in dotted-decimal or IPv4 address notation, such as area 1000 or area 0.0.3.232. However, you must choose one form or the other for an area. We recommend using the IPv4 address notation. Cisco IOS XR Routing Configuration Guide RC-151 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 5 Command or Action Purpose network {broadcast | non-broadcast | {point-to-multipoint [non-broadcast] | point-to-point}} Configures the OSPF network type to a type other than the default for a given medium. • The example sets the network type to NBMA. Example: RP/0/RP0/CPU0:router(config-ospf-ar)# network non-broadcast Step 6 dead-interval seconds (Optional) Sets the time to wait for a hello packet from a neighbor before declaring the neighbor down. Example: RP/0/RP0/CPU0:router(config-ospf-ar)# dead-interval 40 Step 7 hello-interval seconds (Optional) Specifies the interval between hello packets that OSPF sends on the interface. Example: RP/0/RP0/CPU0:router(config-ospf-ar)# hello-interval 10 Step 8 interface type instance Example: RP/0/RP0/CPU0:router(config-ospf-ar)# interface POS 0/2/0/0 Cisco IOS XR Routing Configuration Guide RC-152 Enters interface configuration mode and associates one or more interfaces for the area configured in Step 4. • In this example, the interface inherits the nonbroadcast network type and the hello and dead intervals from the areas because the values are not set at the interface level. Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 9 Command or Action Purpose neighbor ip-address [priority number] [poll-interval seconds][cost number] Configures the IPv4 address of OSPF neighbors interconnecting to nonbroadcast networks. or neighbor ipv6-link-local-address [priority number] [poll-interval seconds][cost number] [database-filter [all]] or Configures the link-local IPv6 address of OSPFv3 neighbors. • The ipv6-link-local-address must be in the form that is specified in RFC 2373. The address is specified in hexadecimal using 16-bit values between colons. • The priority keyword notifies the router that this neighbor is eligible to become a DR or BDR. The priority value should match the actual priority setting on the neighbor router. The neighbor priority default value is 0. This keyword does not apply to point-to-multipoint interfaces. • The poll-interval keyword does not apply to point-to-multipoint interfaces. RFC 1247 recommends that this value be much larger than the hello interval. The default is 120 seconds (2 minutes). • Neighbors with no specific cost configured assumes the cost of the interface, based on the cost command. On point-to-multipoint interfaces, cost number is the only keyword and argument combination that works. The cost keyword does not apply to NBMA networks. • The database-filter keyword filters outgoing LSAs to an OSPF neighbor. If you specify the all keyword, incoming and outgoing LSAs are filtered. Use with extreme caution because filtering might cause the routing topology to be seen as entirely different between two neighbors, resulting in black-holing of data traffic or routing loops. Example: RP/0/RP0/CPU0:router(config-ospf-ar-if)# neighbor 10.20.20.1 priority 3 poll-interval 15 or RP/0/RP0/CPU0:router(config-ospf-ar-if)# neighbor fe80::3203:a0ff:fe9d:f3fe Step 10 Repeat Step 9 for all neighbors on the interface. — Step 11 exit Enters area configuration mode. Example: RP/0/RP0/CPU0:router(config-ospf-ar-if)# exit Step 12 interface type instance Example: RP/0/RP0/CPU0:router(config-ospf-ar)# interface POS 0/3/0/1 Enters interface configuration mode and associates one or more interfaces for the area configured in Step 4. • In this example, the interface inherits the nonbroadcast network type and the hello and dead intervals from the areas because the values are not set at the interface level. Cisco IOS XR Routing Configuration Guide RC-153 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 13 Command or Action Purpose neighbor ip-address [priority number] [poll-interval seconds][cost number] [database-filter [all]] Configures the IPv4 address of OSPF neighbors interconnecting to nonbroadcast networks. or or neighbor ipv6-link-local-address [priority number] [poll-interval seconds][cost number] [database-filter [all]] Configures the link-local IPv6 address of OSPFv3 neighbors. • The ipv6-link-local-address argument must be in the form documented in RFC 2373 in which the address is specified in hexadecimal using 16-bit values between colons. • The priority keyword notifies the router that this neighbor is eligible to become a DR or BDR. The priority value should match the actual priority setting on the neighbor router. The neighbor priority default value is zero. This keyword does not apply to point-to-multipoint interfaces. • The poll-interval keyword does not apply to point-to-multipoint interfaces. RFC 1247 recommends that this value be much larger than the hello interval. The default is 120 seconds (2 minutes). • Neighbors with no specific cost configured assumes the cost of the interface, based on the cost command. On point-to-multipoint interfaces, cost number is the only keyword and argument combination that works. The cost keyword does not apply to NBMA networks. • The database-filter keyword filters outgoing LSAs to an OSPF neighbor. If you specify the all keyword, incoming and outgoing LSAs are filtered. Use with extreme caution since filtering may cause the routing topology to be seen as entirely different between two neighbors, resulting in ‘black-holing’ or routing loops. Example: RP/0/RP0/CPU0:router(config-ospf-ar)# neighbor 10.34.16.6 or RP/0/RP0/CPU0:router(config-ospf-ar)# neighbor fe80::3203:a0ff:fe9d:f3f Cisco IOS XR Routing Configuration Guide RC-154 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Command or Action Purpose Step 14 Repeat Step 13 for all neighbors on the interface. — Step 15 end Saves configuration changes. or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-ospf-ar)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-ospf-ar)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Configuring Authentication at Different Hierarchical Levels for OSPF Version 2 This task explains how to configure MD5 (secure) authentication on the OSPF router process, configure one area with plain text authentication, and then apply one interface with clear text (null) authentication. Note Authentication configured at the interface level overrides authentication configured at the area level and the router process level. If an interface does not have authentication specifically configured, the interface inherits the authentication parameter value from a higher hierarchical level. See the “OSPF Hierarchical CLI and CLI Inheritance” section on page RC-131 for more information about hierarchy and inheritance. Prerequisites If you choose to configure authentication, you must first decide whether to configure plain text or MD5 authentication, and whether the authentication applies to all interfaces in a process, an entire area, or specific interfaces. See the “Route Authentication Methods for OSPF Version 2” section on page RC-135 for information about each type of authentication and when you should use a specific method for your network. SUMMARY STEPS 1. configure 2. router ospf process-name 3. router-id {ipv4-address | interface-type interface-instance} 4. authentication [message-digest | null] Cisco IOS XR Routing Configuration Guide RC-155 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software 5. message-digest-key key-id md5 {key | clear key | encrypted key} 6. area area-id 7. interface type instance 8. Repeat Step 7 for each interface that must communicate, using the same authentication. 9. exit 10. area area-id 11. authentication [message-digest | null] 12. interface type instance 13. Repeat Step 7 for each interface that must communicate, using the same authentication. 14. interface type instance 15. authentication [message-digest | null] 16. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router ospf process-name Enables OSPF routing for the specified routing process, and places the router in router configuration mode. Example: Note RP/0/RP0/CPU0:router(config)# router ospf 1 Step 3 router-id {ipv4-address | interface-type interface-instance} The process-name argument is any alphanumeric string no longer than 40 characters. Configures a router ID for the OSPF process. Example: RP/0/RP0/CPU0:router(config-ospf)# router-id 192.168.4.3 Step 4 authentication [message-digest | null] Enables MD5 authentication for the OSPF process. • Example: RP/0/RP0/CPU0:router(config-ospf)# authentication message-digest Step 5 message-digest-key key-id md5 {key | clear key | encrypted key} Specifies the MD5 authentication key for the OSPF process. • Example: RP/0/RP0/CPU0:router(config-ospf)# message-digest-key 4 md5 yourkey Cisco IOS XR Routing Configuration Guide RC-156 This authentication type applies to the entire router process unless overridden by a lower hierarchical level such as the area or interface. The neighbor routers must have the same key identifier. Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 6 Command or Action Purpose area area-id Enters area configuration mode and configures a backbone area for the OSPF process. Example: RP/0/RP0/CPU0:router(config-ospf)# area 0 Step 7 interface type instance Example: Enters interface configuration mode and associates one or more interfaces to the backbone area. • RP/0/RP0/CPU0:router(config-ospf-ar)# interface POS 0/1/0/3 All interfaces inherit the authentication parameter values specified for the OSPF process (Step 4, Step 5, and Step 6). Step 8 Repeat Step 7 for each interface that must communicate, using the same authentication. — Step 9 exit Enters area OSPF configuration mode. Example: RP/0/RP0/CPU0:router(config-ospf-ar)# exit Step 10 area area-id Example: Enters area configuration mode and configures a nonbackbone area 1 for the OSPF process. • RP/0/RP0/CPU0:router(config-ospf)# area 1 Step 11 authentication [message-digest | null] Example: Enables Type 1 (plain text) authentication that provides no security. • RP/0/RP0/CPU0:router(config-ospf-ar)# authentication Step 12 interface type instance Example: RP/0/RP0/CPU0:router(config-ospf-ar)# interface POS 0/1/0/0 The area-id argument can be entered in dotted-decimal or IPv4 address notation, such as area 1000 or area 0.0.3.232. However, you must choose one form or the other for an area. We recommend using the IPv4 address notation. The example specifies plain text authentication (by not specifying a keyword). Use the authentication-key interface command to specify the plain text password. Enters interface configuration mode and associates one or more interfaces to the nonbackbone area 1 specified in Step 7. • All interfaces configured inherit the authentication parameter values configured for area 1. Step 13 Repeat Step 12 for each interface that must communicate, using the same authentication. — Step 14 interface type instance Enters interface configuration mode and associates one or more interfaces to a different authentication type. Example: RP/0/RP0/CPU0:router(config-ospf-ar)# interface POS 0/3/0/0 Cisco IOS XR Routing Configuration Guide RC-157 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 15 Command or Action Purpose authentication [message-digest | null] Specifies no authentication on POS interface 0/3/0/0, overriding the plain text authentication specified for area 1. • Example: RP/0/RP0/CPU0:router(config-ospf-ar-if)# authentication null Step 16 By default, all of the interfaces configured in the same area inherit the same authentication values of the area. Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-ospf-ar-if)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-ospf-ar-if)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Controlling the Frequency that the Same LSA Is Originated or Accepted for OSPF This task explains how to tune the convergence time of OSPF routes in the routing table when many LSAs need to be flooded in a very short time interval. SUMMARY STEPS 1. configure 2. router ospf process-name or router ospfv3 process-name 3. router-id {ipv4-address | interface-type interface-instance} 4. Do Step 5, Step 6 or both to control the frequency that the same LSA is originated or accepted. 5. timers lsa gen-interval seconds 6. timers lsa min-arrival seconds 7. timers lsa group-pacing seconds 8. end or commit Cisco IOS XR Routing Configuration Guide RC-158 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router ospf process-name or router ospfv3 process-name Example: Enables OSPF routing for the specified routing process, and places the router in router configuration mode. or Enables OSPFv3 routing for the specified routing process, and places the router in router ospfv3 configuration mode. RP/0/RP0/CPU0:router(config)# router ospf 1 or Note The process-name argument is any alphanumeric string no longer than 40 characters. RP/0/RP0/CPU0:router(config)# router ospfv3 1 Step 3 router-id {ipv4-address | interface-type interface-instance} Configures a router ID for the OSPF process. Note We recommend using a stable IP address as the router ID. Example: RP/0/RP0/CPU0:router(config-ospf)# router-id 192.168.4.3 Step 4 Perform Step 5 or Step 6 or both to control the — frequency that the same LSA is originated or accepted. Step 5 timers lsa gen-interval seconds Example: Changes the minimum interval between the same OSPF LSAs that the router originates. • The default is 5 seconds for both OSPF and OSPFv3. RP/0/RP0/CPU0:router(config-ospf)# timers lsa gen-interval 10 Step 6 timers lsa min-arrival seconds Example: Limits the frequency that new processes of any particular OSPF Version 2 LSA can be accepted during flooding. • The default is 1 second. RP/0/RP0/CPU0:router(config-ospf)# timers lsa min-arrival 2 Cisco IOS XR Routing Configuration Guide RC-159 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 7 Command or Action Purpose timers lsa group-pacing seconds Changes the interval at which OSPF link-state LSAs are collected into a group for flooding. The default is 240 seconds. Example: RP/0/RP0/CPU0:router(config-ospf)# timers lsa group-pacing 1000 Step 8 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-ospf)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-ospf)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Creating a Virtual Link with MD5 Authentication to Area 0 for OSPF This task explains how to create a virtual link to your backbone (area 0) and apply MD5 authentication. You must perform the steps described on both ABRs, one at each end of the virtual link. To understand virtual links, see the “Virtual Link and Transit Area for OSPF” section on page RC-138. Note After you explicitly configure area parameter values, they are inherited by all interfaces bound to that area—unless you override the values and configure them explicitly for the interface. An example is provided in the “Virtual Link Configured with MD5 Authentication for OSPF Version 2: Example” section on page RC-192. Prerequisites Meet the following prerequisites before you create a virtual link with MD5 authentication to area 0: • Have the router ID of the neighbor router at the opposite end of the link to configure the local router. You can use the show ospf or show ospfv3 command on the remote end to get its router ID. Cisco IOS XR Routing Configuration Guide RC-160 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software • For a virtual link to be successful, you need a stable router ID at each end of the virtual link. You do not want them to be subject to change, which could happen if they are assigned by default (See the “OSPF Process and Router ID” section on page RC-134 for an explanation of how the router ID is determined.) Therefore, we recommend that you perform one of the following tasks before configuring a virtual link: – Use the router-id command to set the router ID. This strategy is preferable. – Configure a loopback interface so that the router has a stable router ID. • Note Before configuring your virtual link for OSPF Version 2, you must decide whether to configure plain text authentication, MD5 authentication, or no authentication (which is the default). Your decision determines whether you need to perform additional tasks related to authentication. If you decide to configure plain text authentication or no authentication, see the authentication command provided in the OSPF Commands on Cisco IOS XR Software module in the Cisco IOS XR Routing Command Reference. SUMMARY STEPS 1. show ospf [process-name] or show ospfv3 [process-name] 2. configure 3. router ospf process-name or router ospfv3 process-name 4. router-id {ipv4-address | interface-type interface-instance} 5. area area-id 6. virtual link router-id 7. authentication message-digest 8. message-digest-key key-id md5 {key | clear key | encrypted key} 9. Repeat all of the steps in this task on the ABR that is at the other end of the virtual link. Specify the same key ID and key that you specified for the virtual link on this router. 10. end or commit 11. show ospf [process-name] [area-id] virtual-links or show ospfv3 [process-name] virtual-links Cisco IOS XR Routing Configuration Guide RC-161 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose show ospf [process-name] (Optional) Displays general information about OSPF routing processes. or show ospfv3 [process-name] • Example: The output displays the router ID of the local router. You need this router ID to configure the other end of the link. RP/0/RP0/CPU0:router# show ospf or RP/0/RP0/CPU0:router# show ospfv3 Step 2 configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 3 router ospf process-name or router ospfv3 process-name Example: Enables OSPF routing for the specified routing process, and places the router in router configuration mode. or Enables OSPFv3 routing for the specified routing process, and places the router in router ospfv3 configuration mode. RP/0/RP0/CPU0:router(config)# router ospf 1 Note or The process-name argument is any alphanumeric string no longer than 40 characters. RP/0/RP0/CPU0:router(config)# router ospfv3 1 Step 4 router-id {ipv4-address | interface-type interface-instance} Configures a router ID for the OSPF process. Note We recommend using a stable IPv4 address as the router ID. Example: RP/0/RP0/CPU0:router(config-ospf)# router-id 192.168.4.3 Step 5 area area-id Example: Enters area configuration mode and configures a nonbackbone area for the OSPF process. • RP/0/RP0/CPU0:router(config-ospf)# area 1 Step 6 virtual-link router-id Defines an OSPF virtual link. • Example: The area-id argument can be entered in dotted-decimal or IPv4 address notation, such as area 1000 or area 0.0.3.232. However, you must choose one form or the other for an area. We recommend using the IPv4 address notation. See the “Virtual Link and Transit Area for OSPF” section on page RC-138. RP/0/RP0/CPU0:router(config-ospf-ar)# virtual link 10.3.4.5 Step 7 authentication message-digest Example: RP/0/RP0/CPU0:router(config-ospf-ar-vl)# authentication message-digest Cisco IOS XR Routing Configuration Guide RC-162 Selects MD5 authentication for this virtual link. Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 8 Command or Action Purpose message-digest-key key-id md5 {key | clear key | encrypted key} Defines an OSPF virtual link. Example: RP/0/RP0/CPU0:router(config-ospf-ar-vl)# message-digest-key 4 md5 yourkey • See the “Virtual Link and Transit Area for OSPF” section on page RC-138 to understand a virtual link. • The key-id argument is a number in the range from 1 to 255. The key argument is an alphanumeric string of up to 16 characters. The routers at both ends of the virtual link must have the same key identifier and key to be able to route OSPF traffic. • The authentication-key key command is not supported for OSPFv3. • Once the key is encrypted it must remain encrypted. Step 9 Repeat all of the steps in this task on the ABR that is at the other end of the virtual link. Specify the same key ID and key that you specified for the virtual link on this router. — Step 10 end Saves configuration changes. or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-ospf-ar-vl)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-ospf-ar-vl)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Step 11 show ospf [process-name] [area-id] virtual-links or Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. (Optional) Displays the parameters and the current state of OSPF virtual links. show ospfv3 [process-name] virtual-links Example: RP/0/RP0/CPU0:router# show ospf 1 2 virtual-links or RP/0/RP0/CPU0:router# show ospfv3 1 virtual-links Cisco IOS XR Routing Configuration Guide RC-163 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Examples In the following example, the show ospfv3 virtual links EXEC command verifies that the OSPF_VL0 virtual link to the OSPFv3 neighbor is up, the ID of the virtual link interface is 2, and the IPv6 address of the virtual link endpoint is 2003:3000::1. RP/0/RP0/CPU0:router# show ospfv3 virtual-links Virtual Links for OSPFv3 1 Virtual Link OSPF_VL0 to router 10.0.0.3 is up Interface ID 2, IPv6 address 2003:3000::1 Run as demand circuit DoNotAge LSA allowed. Transit area 0.1.20.255, via interface POS 0/1/0/1, Cost of using 2 Transmit Delay is 5 sec, State POINT_TO_POINT, Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:02 Adjacency State FULL (Hello suppressed) Index 0/2/3, retransmission queue length 0, number of retransmission 1 First 0(0)/0(0)/0(0) Next 0(0)/0(0)/0(0) Last retransmission scan length is 1, maximum is 1 Last retransmission scan time is 0 msec, maximum is 0 msec Check for lines: Virtual Link OSPF_VL0 to router 10.0.0.3 is up Adjacency State FULL (Hello suppressed) State is up and Adjacency State is FULL Summarizing Subnetwork LSAs on an OSPF ABR If you configured two or more subnetworks when you assigned your IP addresses to your interfaces, you might want the software to summarize (aggregate) into a single LSA all of the subnetworks that the local area advertises to another area. Such summarization would reduce the number of LSAs and thereby conserve network resources. This summarization is known as interarea route summarization. It applies to routes from within the autonomous system. It does not apply to external routes injected into OSPF by way of redistribution. This task configures OSPF to summarize subnetworks into one LSA, by specifying that all subnetworks that fall into a range are advertised together. This task is performed on an ABR only. SUMMARY STEPS 1. configure 2. router ospf process-name or router ospfv3 process-name 3. router-id {ipv4-address | interface-type interface-instance} 4. area area-id 5. range ip-address mask [advertise | not-advertise] or range ipv6-prefix/prefix-length [advertise | not-advertise] 6. interface type instance Cisco IOS XR Routing Configuration Guide RC-164 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software 7. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router ospf process-name or router ospfv3 process-name Example: Enables OSPF routing for the specified routing process, and places the router in router configuration mode. or Enables OSPFv3 routing for the specified routing process, and places the router in router ospfv3 configuration mode. RP/0/RP0/CPU0:router(config)# router ospf 1 or Note The process-name argument is any alphanumeric string no longer than 40 characters. RP/0/RP0/CPU0:router(config)# router ospfv3 1 Step 3 router-id {ipv4-address | interface-type interface-instance} Configures a router ID for the OSPF process. Note We recommend using a stable IPv4 address as the router ID. Example: RP/0/RP0/CPU0:router(config-ospf)# router-id 192.168.4.3 Step 4 area area-id Example: Enters area configuration mode and configures a nonbackbone area for the OSPF process. • RP/0/RP0/CPU0:router(config-ospf)# area 0 Step 5 range ip-address mask [advertise | not-advertise] or range ipv6-prefix/prefix-length [advertise | not-advertise] Example: Consolidates and summarizes OSPF routes at an area boundary. • The advertise keyword causes the software to advertise the address range of subnetworks in a Type 3 summary LSA. • The not-advertise keyword causes the software to suppress the Type 3 summary LSA, and the subnetworks in the range remain hidden from other areas. • In the first example, all subnetworks for network 192.168.0.0 are summarized and advertised by the ABR into areas outside the backbone. • In the second example, two or more IPv4 interfaces are covered by a 192.x.x network. RP/0/RP0/CPU0:router(config-ospf-ar)# range 192.168.0.0 255.255.0.0 advertise or Example: RP/0/RP0/CPU0:router(config-ospf-ar)# range 4004:f000::/32 advertise The area-id argument can be entered in dotted-decimal or IPv4 address notation, such as area 1000 or area 0.0.3.232. However, you must choose one form or the other for an area. We recommend using the IPv4 address notation. Cisco IOS XR Routing Configuration Guide RC-165 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 6 Command or Action Purpose interface type instance Enters interface configuration mode and associates one or more interfaces to the area. Example: RP/0/RP0/CPU0:router(config-ospf-ar)# interface POS 0/2/0/3 Step 7 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-ospf-ar)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-ospf-ar)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Redistributing Routes from One IGP into OSPF This task redistributes routes from an IGP (could be a different OSPF process) into OSPF. Prerequisites For information about configuring routing policy, see the Implementing Routing Policy on Cisco IOS XR Software module. SUMMARY STEPS 1. configure 2. router ospf process-name or router ospfv3 process-name 3. router-id {ipv4-address | interface-type interface-instance} 4. redistribute protocol [process-id] {level-1 | level-1-2 | level-2} [metric metric-value] [metric-type type-value] [match {internal | external [1 | 2} | nssa-external [1 | 2}] [tag tag-value] [route-map map-tag | policy policy-tag] Cisco IOS XR Routing Configuration Guide RC-166 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software 5. summary-prefix address mask [not-advertise] [tag tag] or summary-prefix ipv6-prefix/prefix-length [not-advertise] [tag tag] 6. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router ospf process-name or router ospfv3 process-name Example: Enables OSPF routing for the specified routing process, and places the router in router configuration mode. or Enables OSPFv3 routing for the specified routing process, and places the router in router ospfv3 configuration mode. RP/0/RP0/CPU0:router(config)# router ospf 1 or Note RP/0/RP0/CPU0:router(config)# router ospfv3 1 Step 3 router-id {ipv4-address | interface-type interface-instance} The process-name argument is any alphanumeric string no longer than 40 characters. Configures a router ID for the OSPF process. Note We recommend using a stable IPv4 address as the router ID. Example: RP/0/RP0/CPU0:router(config-ospf)# router-id 192.168.4.3 Cisco IOS XR Routing Configuration Guide RC-167 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 4 Command or Action Purpose redistribute protocol [process-id] {level-1 | level-1-2 | level-2} [metric metric-value] [metric-type type-value] [match {internal | external [1 | 2} | nssa-external [1 | 2}] [tag tag-value] [route-map map-tag | policy policy-tag] Redistributes OSPF routes from one routing domain to another routing domain. Example: RP/0/RP0/CPU0:router(config-ospf)# redistribute bgp 1 level-1 or RP/0/RP0/CPU0:router(config-router)# redistribute bgp 1 level-1-2 metric-type 1 or Redistributes OSPFv3 routes from one routing domain to another routing domain. • This command causes the router to become an ASBR by definition. • OSPF tags all routes learned through redistribution as external. • The protocol and its process ID, if it has one, indicate the protocol being redistributed into OSPF. • The metric is the cost you assign to the external route. The default is 20 for all protocols except BGP, whose default metric is 1. • The OSPF example redistributes BGP autonomous system 1, Level 1 routes into OSPF as Type 2 external routes. • The OSPFv3 example redistributes BGP autonomous system 1, Level 1 and 2 routes into OSPF. The external link type associated with the default route advertised into the OSPFv3 routing domain is the Type 1 external route. Note Cisco IOS XR Routing Configuration Guide RC-168 RPL is not supported for OSPFv3. Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 5 Command or Action Purpose summary-prefix address mask [not-advertise] [tag tag] (Optional) Creates aggregate addresses for OSPF. or or summary-prefix ipv6-prefix/prefix-length [not-advertise] [tag tag] (Optional) Creates aggregate addresses for OSPFv3. Example: • This command provides external route summarization of the non-OSPF routes. • External ranges that are being summarized should be contiguous. Summarization of overlapping ranges from two different routers could cause packets to be sent to the wrong destination. • This command is optional. If you do not specify it, each route is included in the link-state database and advertised in LSAs. • In the OSPFv2 example, the summary address 10.1.0.0 includes address 10.1.1.0, 10.1.2.0, 10.1.3.0, and so on. Only the address 10.1.0.0 is advertised in an external LSA. • In the OSPFv3 example, the summary address 2010:11:22::/32 has addresses such as 2010:11:22:0:1000::1, 2010:11:22:0:2000:679:1, and so on. Only the address 2010:11:22::/32 is advertised in the external LSA. RP/0/RP0/CPU0:router(config-ospf)# summary-prefix 10.1.0.0 255.255.0.0 or RP/0/RP0/CPU0:router(config-router)# summary-prefix 2010:11:22::/32 Step 6 end or Saves configuration changes. commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-ospf)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-ospf)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Cisco IOS XR Routing Configuration Guide RC-169 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Configuring OSPF Shortest Path First Throttling This task explains how to configure SPF scheduling in millisecond intervals and potentially delay SPF calculations during times of network instability. This task is optional. Prerequisites See the “OSPF Shortest Path First Throttling” section on page RC-139 for information about OSPF SPF throttling. SUMMARY STEPS 1. configure 2. router ospf process-name or router ospfv3 process-name 3. router-id {ipv4-address | interface-type interface-instance} 4. timers throttle spf spf-start spf-hold spf-max-wait 5. area area-id 6. interface type instance 7. end or commit 8. show ospf [process-name] or show ospfv3 [process-name] DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router ospf process-name or router ospfv3 process-name Example: Enables OSPF routing for the specified routing process, and places the router in router configuration mode. or Enables OSPFv3 routing for the specified routing process, and places the router in router ospfv3 configuration mode. RP/0/RP0/CPU0:router(config)# router ospf 1 Note or RP/0/RP0/CPU0:router(config)# router ospfv3 1 Cisco IOS XR Routing Configuration Guide RC-170 The process-name argument is any alphanumeric string no longer than 40 characters. Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 3 Command or Action Purpose router-id {ipv4-address | interface-type interface-instance} Configures a router ID for the OSPF process. Note We recommend using a stable IPv4 address as the router ID. Example: RP/0/RP0/CPU0:router(config-ospf)# router-id 192.168.4.3 Step 4 timers throttle spf spf-start spf-hold spf-max-wait Sets SPF throttling timers. Example: RP/0/RP0/CPU0:router(config-ospf)# timers throttle spf 10 4800 90000 Step 5 Enters area configuration mode and configures a backbone area. area area-id • Example: RP/0/RP0/CPU0:router(config-ospf)# Step 6 area 0 interface type instance The area-id argument can be entered in dotted-decimal or IPv4 address notation, such as area 1000 or area 0.0.3.232. However, you must choose one form or the other for an area. We recommend using the IPv4 address notation. Enters interface configuration mode and associates one or more interfaces to the area. Example: RP/0/RP0/CPU0:router(config-ospf-ar)# interface POS 0/1/0/3 Cisco IOS XR Routing Configuration Guide RC-171 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 7 Command or Action Purpose end Saves configuration changes. or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-ospf-ar-if)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-ospf-ar-if)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Step 8 show ospf [process-name] Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. (Optional) Displays SPF throttling timers. or show ospfv3 [process-name] Example: RP/0/RP0/CPU0:router# show ospf 1 or RP/0/RP0/CPU0:router# show ospfv3 2 Examples In the following example, the show ospf EXEC command is used to verify that the initial SPF schedule delay time, minimum hold time, and maximum wait time are configured correctly. Additional details are displayed about the OSPF process, such as the router type and redistribution of routes. RP/0/RP0/CPU0:router# show ospf 1 Routing Process "ospf 1" with ID 192.168.4.3 Supports only single TOS(TOS0) routes Supports opaque LSA It is an autonomous system boundary router Redistributing External Routes from, ospf 2 Initial SPF schedule delay 5 msecs Minimum hold time between two consecutive SPFs 100 msecs Maximum wait time between two consecutive SPFs 1000 msecs Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs Number of external LSA 0. Checksum Sum 00000000 Number of opaque AS LSA 0. Checksum Sum 00000000 Number of DCbitless external and opaque AS LSA 0 Number of DoNotAge external and opaque AS LSA 0 Number of areas in this router is 1. 1 normal 0 stub 0 nssa External flood list length 0 Cisco IOS XR Routing Configuration Guide RC-172 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Non-Stop Forwarding enabled Note For a description of each output display field, see the show ospf command in the OSPF Commands on Cisco IOS XR Software module in the Cisco IOS XR Routing Command Reference document. Configuring Nonstop Forwarding for OSPF Version 2 This task explains how to configure OSPF NSF on your NSF-capable router. This task is optional. Prerequisites OSPF NSF requires that all neighbor networking devices be NSF aware, which happens automatically after you install the Cisco IOS XR image on the router. If an NSF-capable router discovers that it has non-NSF-aware neighbors on a particular network segment, it disables NSF capabilities for that segment. Other network segments composed entirely of NSF-capable or NSF-aware routers continue to provide NSF capabilities. See the “Nonstop Forwarding for OSPF Version 2” section on page RC-140 for conceptual information. Restrictions The following are restrictions when configuring nonstop forwarding: • OSPF Cisco NSF for virtual links is not supported. • Neighbors must be NSF aware. 1. configure 2. router ospf process-name 3. router-id {ipv4-address | interface-type interface-instance} 4. nsf or nsf enforce global 5. nsf interval seconds 6. end or commit SUMMARY STEPS Cisco IOS XR Routing Configuration Guide RC-173 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router ospf process-name Enables OSPF routing for the specified routing process, and places the router in router configuration mode. Example: Note RP/0/RP0/CPU0:router(config)# router ospf 1 Step 3 router-id {ipv4-address | interface-type interface-instance} The process-name argument is any alphanumeric string no longer than 40 characters. Configures a router ID for the OSPF process. Note We recommend using a stable IPv4 address as the router ID. Example: RP/0/RP0/CPU0:router(config-ospf)# router-id 192.168.4.3 Step 4 Enables OSPF NSF operations. nsf or • Use the nsf command without the optional enforce and global keywords to abort the NSF restart mechanism on the interfaces of detected non-NSF neighbors and allow NSF neighbors to function properly. • Use the nsf command with the optional enforce and global keywords if the router is expected to perform NSF during restart. However, if non-NSF neighbors are detected, NSF restart is canceled for the entire OSPF process. nsf enforce global Example: RP/0/RP0/CPU0:router(config-ospf)# nsf or RP/0/RP0/CPU0:router(config-ospf)# nsf enforce global Cisco IOS XR Routing Configuration Guide RC-174 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 5 Command or Action Purpose nsf interval seconds Sets the minimum time between NSF restart attempts. Note Example: RP/0/RP0/CPU0:router(config-ospf)# nsf interval 120 Step 6 When you use this command, the OSPF process must be up for at least 90 seconds before OSPF attempts to perform an NSF restart. Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-ospf)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-ospf)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Configuring OSPF Version 2 for MPLS Traffic Engineering This task explains how to configure OSPF for MPLS TE. This task is optional. For a description of the MPLS TE tasks and commands that allow you to configure the router to support tunnels, configure an MPLS tunnel that OSPF can use, and troubleshoot MPLS TE, see the Implementing MPLS Traffic Engineering Configuration Guide. Prerequisites Your network must support the following Cisco IOS XR features before you enable MPLS TE for OSPF on your router: Note • MPLS • IP Cisco Express Forwarding (CEF) You must enter the commands in the following task on every OSPF router in the traffic-engineered portion of your network. Cisco IOS XR Routing Configuration Guide RC-175 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Restrictions MPLS traffic engineering currently supports only a single OSPF area. SUMMARY STEPS 1. configure 2. router ospf process-name 3. router-id {ipv4-address | interface-type interface-instance} 4. mpls traffic-eng area area-id 5. mpls traffic-eng router-id {ip-address | interface-type interface-instance} 6. area area-id 7. interface type instance 8. end or commit 9. show ospf [process-name] [area-id] mpls traffic-eng {link | fragment} DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router ospf process-name Enables OSPF routing for the specified routing process, and places the router in router configuration mode. Example: Note RP/0/RP0/CPU0:router(config)# router ospf 1 Step 3 router-id {ipv4-address | interface-type interface-instance} The process-name argument is any alphanumeric string no longer than 40 characters. Configures a router ID for the OSPF process. Note We recommend using a stable IPv4 address as the router ID. Example: RP/0/RP0/CPU0:router(config-ospf)# router-id 192.168.4.3 Step 4 mpls traffic-eng area area-id Example: RP/0/RP0/CPU0:router(config-ospf)# mpls traffic-eng area 0 Cisco IOS XR Routing Configuration Guide RC-176 Configures the OSPF area for MPLS TE. Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 5 Step 6 Command or Action Purpose mpls traffic-eng router-id {ip-address | interface-type interface-instance} (Optional) Specifies that the traffic engineering router identifier for the node is the IP address associated with a given interface. Example: • This IP address is flooded to all nodes in TE LSAs. RP/0/RP0/CPU0:router(config-ospf)# mpls traffic-eng router-id loopback 0 • For all traffic engineering tunnels originating at other nodes and ending at this node, you must set the tunnel destination to the traffic engineering router identifier of the destination node because that is the address that the traffic engineering topology database at the tunnel head uses for its path calculation. • We recommend that loopback interfaces be used for MPLS TE router ID because they are more stable than physical interfaces. area area-id Example: RP/0/RP0/CPU0:router(config-ospf)# area 0 Step 7 interface type instance Enters area configuration mode and configures an area for the OSPF process. • The area-id argument can be entered in dotted-decimal or IPv4 address notation, such as area 1000 or area 0.0.3.232. However, you must choose one form or the other for an area. Enters interface configuration mode and associates one or more interfaces to the area. Example: RP/0/RP0/CPU0:router(config-ospf-ar)# interface interface loopback0 Cisco IOS XR Routing Configuration Guide RC-177 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 8 Command or Action Purpose end Saves configuration changes. or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-ospf-ar-if)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-ospf-ar-if)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Step 9 show ospf [process-name] [area-id] mpls traffic-eng {link | fragment} Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. (Optional) Displays information about the links and fragments available on the local router for MPLS TE. Example: RP/0/RP0/CPU0:router# show ospf 1 0 mpls traffic-eng link Examples This section provides the following output examples: • Sample Output for the show ospf Command Before Configuring MPLS TE, page RC-178 • Sample Output for the show ospf mpls traffic-eng Command, page RC-179 • Sample Output for the show ospf Command After Configuring MPLS TE, page RC-180 Sample Output for the show ospf Command Before Configuring MPLS TE In the following example, the show route ospf EXEC command verifies that POS interface 0/3/0/0 exists and MPLS TE is not configured: RP/0/RP0/CPU0:router# show route ospf 1 0 O E2 192.168.10.0/24 [110/20] via 192.168.1.2, 00:02:50, POS 0/3/0/0 [110/20] via 192.168.4.1, 00:02:50, POS 0/3/0/1 O E2 192.168.11.0/24 [110/20] via 192.168.1.2, 00:02:50, POS 0/3/0/0 [110/20] via 192.168.4.1, 00:02:50, POS 0/3/0/1 O E2 192.168.244.0/24 [110/20] via 192.168.1.2, 00:02:50, POS 0/3/0/0 [110/20] via 192.168.4.1, 00:02:50, POS 0/3/0/1 O 192.168.12.0/24 [110/2] via 192.168.1.2, 00:02:50, POS 0/3/0/0 [110/2] via 192.168.4.1, 00:02:50, POS 0/3/0/1 Cisco IOS XR Routing Configuration Guide RC-178 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Sample Output for the show ospf mpls traffic-eng Command In the following example, the show ospf mpls traffic-eng EXEC command verifies that the MPLS TE fragments are configured correctly: RP/0/RP0/CPU0:router# show ospf 1 mpls traffic-eng fragment OSPF Router with ID (192.168.4.3) (Process ID 1) Area 0 has 1 MPLS TE fragment. Area instance is 3. MPLS router address is 192.168.4.2 Next fragment ID is 1 Fragment 0 has 1 link. Fragment instance is 3. Fragment has 0 link the same as last update. Fragment advertise MPLS router address Link is associated with fragment 0. Link instance is 3 Link connected to Point-to-Point network Link ID :55.55.55.55 Interface Address :192.168.50.21 Neighbor Address :192.168.4.1 Admin Metric :0 Maximum bandwidth :19440000 Maximum global pool reservable bandwidth :25000000 Maximum sub pool reservable bandwidth :3125000 Number of Priority :8 Global pool unreserved BW Priority 0 : 25000000 Priority 1 : 25000000 Priority 2 : 25000000 Priority 3 : 25000000 Priority 4 : 25000000 Priority 5 : 25000000 Priority 6 : 25000000 Priority 7 : 25000000 Sub pool unreserved BW Priority 0 : 3125000 Priority 1 : 3125000 Priority 2 : 3125000 Priority 3 : 3125000 Priority 4 : 3125000 Priority 5 : 3125000 Priority 6 : 3125000 Priority 7 : 3125000 Affinity Bit :0 In the following example, the show ospf mpls traffic-eng EXEC command verifies that the MPLS TE links on area instance 3 are configured correctly: RP/0/RP0/CPU0:router# show ospf mpls traffic-eng link OSPF Router with ID (192.168.4.1) (Process ID 1) Area 0 has 1 MPLS TE links. Area instance is 3. Links in hash bucket 53. Link is associated with fragment 0. Link instance is 3 Link connected to Point-to-Point network Link ID :192.168.50.20 Interface Address :192.168.20.50 Neighbor Address :192.168.4.1 Admin Metric :0 Maximum bandwidth :19440000 Maximum global pool reservable bandwidth :25000000 Maximum sub pool reservable bandwidth :3125000 Number of Priority :8 Global pool unreserved BW Priority 0 : 25000000 Priority 1 : 25000000 Priority 2 : 25000000 Priority 3 : 25000000 Priority 4 : 25000000 Priority 5 : 25000000 Priority 6 : 25000000 Priority 7 : 25000000 Sub pool unreserved BW Cisco IOS XR Routing Configuration Guide RC-179 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Priority Priority Priority Priority Affinity 0 : 3125000 2 : 3125000 4 : 3125000 6 : 3125000 Bit :0 Priority Priority Priority Priority 1 3 5 7 : : : : 3125000 3125000 3125000 3125000 Sample Output for the show ospf Command After Configuring MPLS TE In the following example, the show route ospf EXEC command verifies that the MPLS TE tunnels replaced POS interface 0/3/0/0 and that configuration was performed correctly: RP/0/RP0/CPU0:router# show route ospf 1 0 O E2 192.168.10.0/24 [110/20] via 0.0.0.0, 00:00:15, tunnel2 O E2 192.168.11.0/24 [110/20] via 0.0.0.0, 00:00:15, tunnel2 O E2 192.168.1244.0/24 [110/20] via 0.0.0.0, 00:00:15, tunnel2 O 192.168.12.0/24 [110/2] via 0.0.0.0, 00:00:15, tunnel2 Verifying OSPF Configuration and Operation This task explains how to verify the configuration and operation of OSPF. Note To execute OSPFv3 commands for this task, replace ospf with ospfv3 in Steps 1 through 7. SUMMARY STEPS 1. show ospf [process-name] 2. show ospf [process-name] border-routers [router-id] 3. show ospf [process-name] database 4. show ospf [process-name] [area-id] flood-list interface type instance 5. show ospf [process-name] [area-id] neighbor [interface-type interface-instance] [neighbor-id] [detail] 6. clear ospf [process-name] process 7. clear ospf [process-name] statistics [neighbor [interface-type interface-instance] [ip-address]] DETAILED STEPS Step 1 Command or Action Purpose show ospf [process-name] (Optional) Displays general information about OSPF routing processes. Example: RP/0/RP0/CPU0:router# show ospf group1 Step 2 show ospf [process-name] border-routers [router-id] Example: RP/0/RP0/CPU0:router# show ospf group1 border-routers Cisco IOS XR Routing Configuration Guide RC-180 (Optional) Displays the internal OSPF routing table entries to an ABR and ASBR. Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Step 3 Command or Action Purpose show ospf [process-name] database (Optional) Displays the lists of information related to the OSPF database for a specific router. • Example: RP/0/RP0/CPU0:router# show ospf group2 database Step 4 show ospf [process-name] [area-id] flood-list interface type instance The various forms of this command deliver information about different OSPF LSAs. (Optional) Displays a list of OSPF LSAs waiting to be flooded over an interface. Example: RP/0/RP0/CPU0:router# show ospf 100 flood-list interface pos 0/3/0/0 Step 5 show ospf [process-name] [area-id] neighbor [interface-type interface-instance] [neighbor-id] [detail] (Optional) Displays OSPF neighbor information on an individual interface basis. Example: RP/0/RP0/CPU0:router# show ospf 100 neighbor Step 6 clear ospf [process-name] process (Optional) Resets an OSPF router process without stopping and restarting it. Example: RP/0/RP0/CPU0:router# clear ospf 100 process Step 7 clear ospf [process-name] statistics [neighbor [interface-type interface-instance] [ip-address]] (Optional) Clears the OSPF statistics of neighbor state transitions. Example: RP/0/RP0/CPU0:router# clear ospf 100 statistics Configuring OSPFv3 Graceful Restart This section describes the following tasks for configuring a graceful restart of an OSPFv3 process: • Enabling Graceful Restart, page RC-182 • Configuring the Maximum Lifetime of a Graceful Restart, page RC-182 • Configuring the Minimum Time Required Between Restarts, page RC-183 • Configuring the Helper Level of the Router, page RC-184 • Displaying Information About Graceful Restart, page RC-185 Cisco IOS XR Routing Configuration Guide RC-181 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Enabling Graceful Restart This section describes how to enable an OSPFv3 graceful restart on the current router. By default, this feature is disabled. SUMMARY STEPS 1. configuration 2. router ospfv3 3. graceful-restart DETAILED STEPS Step 1 Command or Action Purpose config Enters global configuration mode. Example: RP/0/RP0/CPU0:single10-hfr#config RP/0/RP0/CPU0:single10-hfr(config) Step 2 router ospfv3 process-name Example: RP/0/RP0/CPU0:single10-hfr(config)# router ospfv3 test Step 3 graceful-restart Enters router configuration mode for OSPFv3. The process name is a WORD that uniquely identifies an OSPF routing process. The process name is any alphanumeric string no longer than 40 characters without spaces. Enable graceful restart on the current router. Example: RP/0/RP0/CPU0:single10-hfr(config-ospfv3)#grace ful-restart Configuring the Maximum Lifetime of a Graceful Restart This section describes the task of modifying the total time that a router can be in graceful restart mode. The default lifetime is 95 seconds. The range is 90–3600 seconds. SUMMARY STEPS 1. configuration 2. router ospfv3 3. graceful-restart lifetime Cisco IOS XR Routing Configuration Guide RC-182 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose config Enters global configuration mode. Example: RP/0/RP0/CPU0:single10-hfr#config RP/0/RP0/CPU0:single10-hfr(config) Step 2 router ospfv3 Example: RP/0/RP0/CPU0:single10-hfr(config)# router ospfv3 test Step 3 graceful-restart lifetime Enters router configuration mode for OSPFv3. The process name is a WORD that uniquely identifies an OSPF routing process. The process name is any alphanumeric string no longer than 40 characters without spaces. Specifies a maximum duration for a graceful restart. Example: RP/0/RP0/CPU0:single10-hfr(config-ospfv3)#grace ful-restart lifetime 120 Configuring the Minimum Time Required Between Restarts This section describes the task of modifying the minimal time that is required between allowable graceful restarts. The purpose of this interval is to prevent the waste of system resources if the OSPFv3 process is repeatedly crashing for reasons that must be diagnosed. The default value for the interval is 90 seconds. The range is 90–3600 seconds. SUMMARY STEPS 1. configuration 2. router ospfv3 3. graceful-restart interval Cisco IOS XR Routing Configuration Guide RC-183 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose config Enters global configuration mode. Example: RP/0/RP0/CPU0:single10-hfr#config RP/0/RP0/CPU0:single10-hfr(config) Step 2 router ospfv3 Example: RP/0/RP0/CPU0:single10-hfr(config)# router ospfv3 test Step 3 graceful-restart interval Enters router configuration mode for OSPFv3. The process name is a WORD that uniquely identifies an OSPF routing process. The process name is any alphanumeric string no longer than 40 characters without spaces. Specifies the interval (minimal time) between graceful restarts on the current router. Example: RP/0/RP0/CPU0:single10-hfr(config-ospfv3)#grace ful-restart interval 120 Configuring the Helper Level of the Router This section describes the task of disabling the helper mode on the current router. By default, a router that is capable of doing an OSPFv3 graceful restart is also enabled to be a helper to a node in graceful mode. The graceful-restart helper command lets you disable the current router’s helper capability. SUMMARY STEPS 1. configuration 2. router ospfv3 3. graceful-restart helper [disable] Cisco IOS XR Routing Configuration Guide RC-184 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose config Enters global configuration mode. Example: RP/0/RP0/CPU0:single10-hfr#config RP/0/RP0/CPU0:single10-hfr(config) Step 2 router ospfv3 Example: RP/0/RP0/CPU0:single10-hfr(config)# router ospfv3 test Step 3 graceful-restart helper Enters router configuration mode for OSPFv3. The process name is a WORD that uniquely identifies an OSPF routing process. The process name is any alphanumeric string no longer than 40 characters without spaces. Disables the helper capability. Example: RP/0/RP0/CPU0:single10-hfr(config-ospfv3)#grace ful-restart helper disable Displaying Information About Graceful Restart This section describes the tasks you can use to display information about a graceful restart. • To see if the feature is enabled and when the last graceful restart ran, use the show ospf command. To see details for an OSPFv3 instance, use the show ospf process-name database grace command. Displaying the State of the Graceful Restart Feature The following screen output shows the state of the graceful restart capability on the local router: RP/0/0/CPU0:LA#show ospfv3 test database grace Routing Process “ospfv3 test” with ID 2.2.2.2 Initial SPF schedule delay 5000 msecs Minimum hold time between two consecutive SPFs 10000 Maximum wait time between two consecutive SPFs 10000 Initial LSA throttle delay 0 msecs Minimum hold time for LSA throttle 5000 msecs Maximum wait time for LSA throttle 5000 msecs Minimum LSA arrival 1000 msecs LSA group pacing timer 240 secs Interface flood pacing timer 33 msecs Retransmission pacing timer 66 msecs Maximum number of configured interfaces 255 Number of external LSA 0. Checksum Sum 00000000 Number of areas in this router is 1. 1 normal 0 stub Graceful Restart enabled, last GR 11:12:26 ago (took Area BACKBONE(0) Number of interfaces in this area is 1 SPF algorithm executed 1 times Number of LSA 6. Checksum Sum 0x0268a7 Number of DCbitless LSA 0 Number of indication LSA 0 Number of DoNotAge LSA 0 Flood list length 0 RP/0/0/CPU0:LA# msecs msecs 0 nssa 6 secs) Cisco IOS XR Routing Configuration Guide RC-185 Implementing OSPF on Cisco IOS XR Software How to Implement OSPF on Cisco IOS XR Software Displaying Graceful Restart Information for an OSPFv3 Instance The following screen output shows the link state for the instance of OSPFv3 called test: RP/0/0/CPU0:LA#show ospfv3 test database grace OSPFv3 Router with ID (2.2.2.2) (Process ID test) ADV Router 1.1.1.1 2.2.2.2 Router Link States (Area 0) Age Seq# Fragment ID 1949 0x8000000e 0 2007 0x80000011 0 ADV Router 1.1.1.1 s2.2.2.2 Link (Type-8) Link States (Area 0) Age Seq# Link ID 180 0x80000006 1 2007 0x80000006 1 Interface PO0/2/0/0 PO0/2/0/0 ADV Router 1.1.1.1 2.2.2.2 Intra Area Prefix Link States (Area 0) Age Seq# Link ID 180 0x80000006 0 2007 0x80000006 0 Ref-lstype Ref-LSID 0x2001 0x2001 ADV Router 2.2.2.2 Grace (Type-11) Link States (Area 0) Age Seq# Link ID 2007 0x80000005 1 Link count Bits 1 1 None None 0 0 Interface PO0/2/0/0 RP/0/0/CPU0:LA# Enabling Multicast-Intact for OSPFv2 This optional task describes how to enable multicast-intact for OSPFv2 routes that use IPv4 addresses. Summary Steps 1. configure 2. router ospf instance-id 3. mpls traffic-eng multicast-intact 4. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router ospf instance-id Example: RP/0/RP0/CPU0:router(config)# router ospf isp Cisco IOS XR Routing Configuration Guide RC-186 Enables OSPF routing for the specified routing process, and places the router in router configuration mode. In this example, the OSPF instance is called isp. Implementing OSPF on Cisco IOS XR Software Configuration Examples for Implementing OSPF on Cisco IOS XR Software Step 3 Command or Action Purpose mpls traffic-eng multicast-intact Enables multicast-intact. Example: RP/0/RP0/CPU0:router(config-isis)# mpls traffic-eng multicast-intact Step 4 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-isis-af)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config-isis-af)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Configuration Examples for Implementing OSPF on Cisco IOS XR Software This section provides the following configuration examples: • Cisco IOS XR for OSPF Version 2 Configuration: Example, page RC-188 • CLI Inheritance and Precedence for OSPF Version 2: Example, page RC-189 • MPLS TE for OSPF Version 2: Example, page RC-190 • ABR with Summarization for OSPFv3: Example, page RC-190 • ABR Stub Area for OSPFv3: Example, page RC-190 • ABR Totally Stub Area for OSPFv3: Example, page RC-191 • Route Redistribution for OSPFv3: Example, page RC-191 • Virtual Link Configured Through Area 1 for OSPFv3: Example, page RC-191 Cisco IOS XR Routing Configuration Guide RC-187 Implementing OSPF on Cisco IOS XR Software Configuration Examples for Implementing OSPF on Cisco IOS XR Software Cisco IOS XR for OSPF Version 2 Configuration: Example The following example shows how an OSPF interface is configured for an area in Cisco IOS XR software. In Cisco IOS XR software, area 0 must be explicitly configured with the area command and all interfaces that are in the range from 10.1.2.0 to 10.1.2.255 are bound to area 0. Interfaces are configured with the interface command (while the router is in area configuration mode) and the area keyword is not included in the interface statement. Cisco IOS XR Software Configuration interface POS 0/3/0/0 ip address 10.1.2.1 255.255.255.255 negotiation auto ! router ospf 1 router-id 10.2.3.4 area 0 interface POS 0/3/0/0 ! ! The following example shows how OSPF interface parameters are configured for an area in Cisco IOS XR software. In Cisco IOS XR software, OSPF interface-specific parameters are configured in interface configuration mode and explicitly defined for area 0. In addition, the ip ospf keywords are no longer required. Cisco IOS XR Software Configuration interface POS 0/3/0/0 ip address 10.1.2.1 255.255.255.0 negotiation auto ! router ospf 1 router-id 10.2.3.4 area 0 interface POS 0/3/0/0 cost 77 mtu-ignore authentication message-digest message-digest-key 1 md5 0 test ! ! The following example shows the hierarchical CLI structure of Cisco IOS XR software. In Cisco IOS XR software, OSPF areas must be explicitly configured, and interfaces configured under the area configuration mode are explicitly bound to that area. In this example, interface 10.1.2.0/24 is bound to area 0 and interface 10.1.3.0/24 is bound to area 1. Cisco IOS XR Software Configuration interface POS 0/3/0/0 ip address 10.1.2.1 255.255.255.0 negotiation auto ! interface POS 0/3/0/1 ip address 10.1.3.1 255.255.255.0 negotiation auto ! Cisco IOS XR Routing Configuration Guide RC-188 Implementing OSPF on Cisco IOS XR Software Configuration Examples for Implementing OSPF on Cisco IOS XR Software router ospf 1 router-id 10.2.3.4 area 0 interface POS 0/3/0/0 ! area 1 interface POS 0/3/0/1 ! ! CLI Inheritance and Precedence for OSPF Version 2: Example The following example configures the cost parameter at different hierarchical levels of the OSPF topology, and illustrates how the parameter is inherited and how only one setting takes precedence. According to the precedence rule, the most explicit configuration is used. The cost parameter is set to 5 in router configuration mode for the OSPF process. Area 1 sets the cost to 15 and area 6 sets the cost to 30. All interfaces in area 0 inherit a cost of 5 from the OSPF process because the cost was not set in area 0 or its interfaces. In area 1, every interface has a cost of 15 because the cost is set in area 1 and 15 overrides the value 5 that was set in router configuration mode. Area 4 does not set the cost, but POS interface 01/0/2 sets the cost to 20. The remaining interfaces in area 4 have a cost of 5 that is inherited from the OSPF process. Area 6 sets the cost to 30, which is inherited by POS interfaces 0/1/0/3 and 0/2/0/3. POS interface 0/3/0/3 uses the cost of 1, which is set in interface configuration mode. router ospf 1 router-id 10.5.4.3 cost 5 area 0 interface POS 0/1/0/0 ! interface POS 0/2/0/0 ! interface POS 0/3/0/0 ! ! area 1 cost 15 interface POS 0/1/0/1 ! interface POS 0/2/0/1 ! interface POS 0/3/0/1 ! ! area 4 interface POS 0/1/0/2 cost 20 ! interface POS 0/2/0/2 ! interface POS 0/3/0/2 ! ! area 6 cost 30 interface POS 0/1/0/3 ! Cisco IOS XR Routing Configuration Guide RC-189 Implementing OSPF on Cisco IOS XR Software Configuration Examples for Implementing OSPF on Cisco IOS XR Software interface POS 0/2/0/3 ! interface POS 0/3/0/3 cost 1 ! ! MPLS TE for OSPF Version 2: Example The following example shows how to configure the OSPF portion of MPLS TE. However, you still need to build an MPLS TE topology and create an MPLS TE tunnel. See the Cisco IOS XR MPLS Configuration Guide for information. In this example, loopback interface 0 is associated with area 0 and area 0 is declared to be an MPLS area: interface Loopback 0 ip address 10.10.10.10 255.255.255.0 ! interface POS 0/2/0/0 ip address 10.1.2.2 255.255.255.0 ! router ospf 1 router-id 10.10.10.10 nsf auto-cost reference-bandwidth 10000 area 0 interface POS 0/2/0/0 interface Loopback 0 mpls traffic-eng area 0 mpls traffic-eng router-id Loopback 0 ABR with Summarization for OSPFv3: Example The following example shows the prefix range 2300::/16 summarized from area 1 into the backbone: router ospfv3 1 router-id 192.168.0.217 area 0 interface POS 0/2/0/1 area 1 range 2300::/16 interface POS 0/2/0/0 ABR Stub Area for OSPFv3: Example The following example shows that area 1 is configured as a stub area: router ospfv3 1 router-id 10.0.0.217 area 0 interface POS 0/2/0/1 area 1 stub interface POS 0/2/0/0 Cisco IOS XR Routing Configuration Guide RC-190 Implementing OSPF on Cisco IOS XR Software Configuration Examples for Implementing OSPF on Cisco IOS XR Software ABR Totally Stub Area for OSPFv3: Example The following example shows that area 1 is configured as a totally stub area: router ospfv3 1 router-id 10.0.0.217 area 0 interface POS 0/2/0/1 area 1 stub no-summary interface POS 0/2/0/0 Route Redistribution for OSPFv3: Example The following example uses prefix lists to limit the routes redistributed from other protocols. Only routes with 9898:1000 in the upper 32 bits and with prefix lengths from 32 to 64 are redistributed from BGP 42. Only routes not matching this pattern are redistributed from BGP 1956. ipv6 prefix-list list1 seq 10 permit 9898:1000::/32 ge 32 le 64 ipv6 prefix-list list2 seq 10 deny 9898:1000::/32 ge 32 le 64 seq 20 permit ::/0 le 128 router ospfv3 1 router-id 10.0.0.217 redistribute bgp 42 redistribute bgp 1956 distribute-list prefix-list list1 out bgp 42 distribute-list prefix-list list2 out bgp 1956 area 1 interface POS 0/2/0/0 Virtual Link Configured Through Area 1 for OSPFv3: Example This example shows how to set up a virtual link to connect the backbone through area 1 for the OSPFv3 topology that consists of areas 0 and 1 and virtual links 10.0.0.217 and 10.0.0.212: ABR 1 Configuration router ospfv3 1 router-id 10.0.0.217 area 0 interface POS 0/2/0/1 area 1 virtual-link 10.0.0.212 interface POS 0/2/0/0 ABR 2 Configuration router ospfv3 1 router-id 10.0.0.212 area 0 interface POS 0/3/0/1 area 1 virtual-link 10.0.0.217 interface POS 0/2/0/0 Cisco IOS XR Routing Configuration Guide RC-191 Implementing OSPF on Cisco IOS XR Software Where to Go Next Virtual Link Configured with MD5 Authentication for OSPF Version 2: Example The following examples show how to configure a virtual link to your backbone and apply MD5 authentication. You must perform the steps described on both ABRs at each end of the virtual link. After you explicitly configure the ABRs, the configuration is inherited by all interfaces bound to that area—unless you override the values and configure them explicitly for the interface. To understand virtual links, see the “Virtual Link and Transit Area for OSPF” section on page RC-138. In this example, all interfaces on router ABR1 use MD5 authentication: router ospf ABR1 router-id 10.10.10.10 authentication message-digest message-digest-key 100 md5 0 cisco area 0 interface pos 0/2/0/1 interface pos 0/3/0/0 area 1 interface pos 0/3/0/1 virtual-link 10.10.5.5 ! ! In this example, only area 1 interfaces on router ABR3 use MD5 authentication: router ospf ABR2 router-id 10.10.5.5 area 0 area 1 authentication message-digest message-digest-key 100 md5 0 cisco interface pos 0/9/0/1 virtual-link 10.10.10.10 area 3 interface Loopback 0 interface pos 0/9/0/0 ! ! Where to Go Next To configure route maps through the RPL for OSPF Version 2, see the Implementing Routing Policy on Cisco IOS XR Software document. To build an MPLS TE topology, create tunnels, and configure forwarding over the tunnel for OSPF Version 2; see the Cisco IOS XR MPLS Configuration Guide. Cisco IOS XR Routing Configuration Guide RC-192 Implementing OSPF on Cisco IOS XR Software Additional References Additional References The following sections provide references related to implementing OSPF on Cisco IOS XR software. Related Documents Related Topic Document Title OSPF and OSPFv3 commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples Cisco IOS XR Routing Command Reference, Release 32 MPLS TE feature information Implementing MPLS Traffic Engineering on Cisco IOS XR Software module in the Cisco IOS XR MPLS Configuration Guide, Release 3.2 Standards Standards Title No new or modified standards are supported by this — feature, and support for existing standards has not been modified by this feature. MIBs MIBs • OSPF-MIB MIBs Link To locate and download MIBs for selected platforms using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL: http://cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml RFCs RFCs Title RFC 1587 Not so Stubby Area (NSSA) RFC 1793 OSPF over demand circuit RFC 2328 OSPF Version 2 RFC 2740 OSPFv3 RFC 3623 Graceful OSPF Restart (OSPFv2) Cisco IOS XR Routing Configuration Guide RC-193 Implementing OSPF on Cisco IOS XR Software Additional References Technical Assistance Description Link http://www.cisco.com/techsupport The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content. Cisco IOS XR Routing Configuration Guide RC-194 Implementing and Monitoring RIB on Cisco IOS XR Software Routing Information Base (RIB) is a distributed collection of information about routing connectivity among all nodes of a network. Each router maintains a RIB containing the routing information for that router. RIB stores the best routes from all routing protocols that are running on the system. This module describes the tasks you need to perform to implement and monitor RIB on your Cisco IOS XR network. Note For more information about RIB on the Cisco IOS XR software and complete descriptions of RIB commands listed in this module, see the “Related Documents” of this module. To locate documentation for other commands that might appear during the execution of a configuration task, search online in the Cisco IOS XR software master command index. Feature History for Implementing and Monitoring RIB on Cisco IOS XR Software Release Modification Release 2.0 This feature was introduced on the Cisco CRS-1. Release 3.0 No modification. Release 3.2 Support was added for the Cisco XR 12000 Series Router. Contents • Prerequisites for Implementing RIB on Cisco IOS XR Software, page RC-196 • Information About RIB Configuration, page RC-196 • How to Deploy and Monitor RIB, page RC-198 • Configuration Examples for RIB Monitoring, page RC-200 • Where to Go Next, page RC-202 • Additional References, page RC-203 Cisco IOS XR Routing Configuration Guide RC-195 Implementing and Monitoring RIB on Cisco IOS XR Software Prerequisites for Implementing RIB on Cisco IOS XR Software Prerequisites for Implementing RIB on Cisco IOS XR Software • To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide. • RIB is distributed with the base Cisco IOS XR software; as such, it does not have any special requirements for installation. The following are the requirements for base software installation: – Router – Cisco IOS XR software – Base package Information About RIB Configuration To implement the Cisco RIB feature, you must understand the following concepts: • Overview of RIB, page RC-196 • RIB Data Structures in BGP and Other Protocols, page RC-196 • RIB Administrative Distance, page RC-197 • RIB Support for IPv4 and IPv6, page RC-197 Overview of RIB Each routing protocol selects its own set of best routes and installs those routes and their attributes in RIB. RIB stores these routes and selects the best ones from among all routing protocols. Those routes are downloaded to the line cards for use in forwarding packets. The acronym RIB is used both to refer to RIB processes and the collection of route data contained within RIB. Within a protocol, routes are selected based on the metrics in use by that protocol. A protocol downloads its best routes (lowest or tied metric) to RIB. RIB selects the best overall route by comparing the administrative distance of the associated protocol. RIB Data Structures in BGP and Other Protocols RIB uses processes and maintains data structures distinct from other routing applications, such as Border Gateway Protocol (BGP) and other unicast routing protocols, or multicast protocols, such as Protocol Independent Multicast (PIM) or Multicast Source Discovery Protocol (MSDP). However, these routing protocols use internal data structures similar to what RIB uses, and may internally refer to the data structures as a RIB. For example, BGP routes are stored in the BGP RIB (BRIB), and multicast routes, computed by multicast routing protocols such as PIM and MSDP, are stored in the Multicast RIB (MRIB). RIB processes are not responsible for the BRIB and MRIB, which are handled by BGP and multicast processes, respectively. The table used by the line cards and RP to forward packets is called the Forwarding Information Base (FIB). RIB processes do not build the FIBs. Instead, RIB downloads the set of selected best routes to the FIB processes, by the Bulk Content Downloader (BCDL) process, onto each line card. FIBs are then constructed. Cisco IOS XR Routing Configuration Guide RC-196 Implementing and Monitoring RIB on Cisco IOS XR Software Information About RIB Configuration RIB Administrative Distance Forwarding is done based on the longest prefix match. If you are forwarding a packet destined to 10.0.2.1, you prefer 10.0.2.0/24 over 10.0.0.0/16 because the mask /24 is longer (and more specific) than a /16. Routes from different protocols that have the same prefix and length are chosen based on administrative distance. For instance, the Open Shortest Path First (OSPF) protocol has an administrative distance of 110, and the Intermediate System-to-Intermediate System (IS-IS) protocol has an administrative distance of 115. If IS-IS and OSPF both download 10.0.1.0/24 to RIB, RIB would prefer the OSPF route because OSPF has a lower administrative distance. Administrative distance is used only to choose between multiple routes of the same length. The default administrative distances for the common protocols are shown in Table 2. Table 2 Default Administrative Distances Protocol Administrative Distance Default Connected or local routes 0 Static routes 1 External BGP routes 20 OSPF routes 110 IS-IS routes 115 Internal BGP routes 200 The administrative distance for some routing protocols (for instance IS-IS, OSPF, and BGP) can be changed. See the protocol-specific documentation for the proper method to change the administrative distance of that protocol. Note Changing the administrative distance of a protocol on some but not all routers can lead to routing loops and other undesirable behavior. Doing so is not recommended. RIB Support for IPv4 and IPv6 In Cisco IOS XR software, RIB tables support multicast and unicast routing. The default routing table for Cisco IOS XR RIB are the unicast and the multicast-unicast RIB tables for IPv4 and IPv6 routing, respectively. For multicast routing, routing protocols insert unicast routes into the multicast-unicast RIB table. Multicast protocols then use the information to build multicast routes (which in turn are stored in the MRIB). See the multicast documentation for more information on using and configuring multicast. RIB processes ipv4_rib and ipv6_rib run on the RP card. If process placement functionality is available and supported by multiple RPs in the router, RIB processes can be placed on any available node. Cisco IOS XR Routing Configuration Guide RC-197 Implementing and Monitoring RIB on Cisco IOS XR Software How to Deploy and Monitor RIB How to Deploy and Monitor RIB To deploy and monitor RIB, you must understand the following concepts: • Verifying RIB Configuration Using the Routing Table, page RC-198 (required) • Verifying Networking and Routing Problems, page RC-198 (required) Verifying RIB Configuration Using the Routing Table This task verifies the RIB configuration to ensure that RIB is running on the RP and functioning properly by checking the routing table summary and details. SUMMARY STEPS 1. show route [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] summary 2. show route [protocol [process-id]] [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] [ip-address [mask]] DETAILED STEPS Step 1 Command or Action Purpose show route [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] summary Displays route summary information on the specified routing table. • Example: The default table summarized is the IPv4 unicast routing table. RP/0/RP0/CPU0:router# show route summary Step 2 show route [protocol [process-id]] [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] [ip-address [ mask]] Displays more detailed route information on the specified routing table. • Example: RP/0/RP0/CPU0:router# show route ipv4 unicast This command is usually issued with an IP address or other optional filters to limit its display. Otherwise, it displays all routes from the default IPv4 unicast routing table, which can result in an extensive list, depending on the configuration of the network. Verifying Networking and Routing Problems This task verifies the operation of the routes between nodes. SUMMARY STEPS 1. show route [protocol [instance]] [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] [ip-address [mask]] 2. show route [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] backup [ip-address] 3. show route [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] best-local ip-address 4. show route [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] connected Cisco IOS XR Routing Configuration Guide RC-198 Implementing and Monitoring RIB on Cisco IOS XR Software How to Deploy and Monitor RIB 5. show route [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] local [interface] 6. show route [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] ip-address mask longer-prefixes 7. show route [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] next-hop ip-address DETAILED STEPS Step 1 Command or Action Purpose show route [protocol [instance]] [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] [ip-address [mask]] Displays the current routes in RIB. Example: RP/0/RP0/CPU0:router# show route list list1 bgp aspo ipv4 unicast 192.168.111/8 Step 2 show route [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] backup [ip-address] Displays backup routes in RIB. Example: RP/0/RP0/CPU0:router# show route ipv4 unicast backup 192.168.111/8 Step 3 show route [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] best-local ip-address Displays the best-local address to use for return packets from the given destination. Example: RP/0/RP0/CPU0:router# show route ipv4 unicast best-local 192.168.111/8 Step 4 show route [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] connected Displays the current connected routes of the routing table. Example: RP/0/RP0/CPU0:router# show route ipv4 unicast connected Step 5 show route [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] local [interface] Displays local routes for receive entries in the routing table. Example: RP/0/RP0/CPU0:router# show route ipv4 unicast local Cisco IOS XR Routing Configuration Guide RC-199 Implementing and Monitoring RIB on Cisco IOS XR Software Configuration Examples for RIB Monitoring Step 6 Command or Action Purpose show route [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] ip-address mask longer-prefixes Displays the current routes in RIB that share a given number of bits with a given network. Example: RP/0/RP0/CPU0:router# show route ipv4 unicast 192.168.111/8 longer-prefixes Step 7 show route [afi-all | ipv4 | ipv6] [unicast | multicast | safi-all] next-hop ip-address Displays the next hop gateway or host to a destination address. Example: RP/0/RP0/CPU0:router# show route ipv4 unicast next-hop 192.168.1.34 Configuration Examples for RIB Monitoring RIB is not configured separately for the Cisco IOS XR system. RIB computes connectivity of the router with other nodes in the network based on input from the routing protocols. RIB may be used to monitor and troubleshoot the connections between RIB and its clients, but it is essentially used to monitor routing connectivity between the nodes in a network. This section contains displays from the show commands used to monitor that activity. The following sample output is provided: • Output of show route Command: Example, page RC-200 • Output of show route backup Command: Example, page RC-201 • Output of show route best-local Command: Example, page RC-201 • Output of show route connected Command: Example, page RC-201 • Output of show route local Command: Example, page RC-201 • Output of show route longer-prefixes Command: Example, page RC-202 • Output of show route next-hop Command: Example, page RC-202 Output of show route Command: Example The following is sample output from the show route command when entered without an address: RP/0/RP0/CPU0:router# show route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP O - OSPF, IA - OSPF inter area, N1 - OSPF NSSA external type 1 N2 - OSPF NSSA external type 2, E1 - OSPF external type 1 E2 - OSPF external type 2, E - EGP, i - ISIS, L1 - IS-IS level-1 L2 - IS-IS level-2, ia - IS-IS inter area su - IS-IS summary null, * - candidate default U - per-user static route, o - ODR, L - local Gateway of last resort is 172.23.54.1 to network 0.0.0.0 C L C 10.2.210.0/24 is directly connected, 1d21h, Ethernet0/1/0/0 10.2.210.221/32 is directly connected, 1d21h, Ethernet0/1/1/0 172.20.16.0/24 is directly connected, 1d21h, ATM4/0.1 Cisco IOS XR Routing Configuration Guide RC-200 Implementing and Monitoring RIB on Cisco IOS XR Software Configuration Examples for RIB Monitoring L C L S 172.20.16.1/32 is directly connected, 1d21h, ATM4/0.1 10.6.100.0/24 is directly connected, 1d21h, Loopback1 10.6.200.21/32 is directly connected, 1d21h, Loopback0 192.168.40.0/24 [1/0] via 172.20.16.6, 1d21h Output of show route backup Command: Example The following is sample output from the show route backup command: RP/0/RP0/CPU0:router# show route backup Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP O - OSPF, IA - OSPF inter area, N1 - OSPF NSSA external type 1 N2 - OSPF NSSA external type 2, E1 - OSPF external type 1 E2 - OSPF external type 2, E - EGP, i - ISIS, L1 - IS-IS level-1 L2 - IS-IS level-2, ia - IS-IS inter area su - IS-IS summary null, * - candidate default U - per-user static route, o - ODR, L - local S 172.73.51.0/24 is directly connected, 2d20h, GigabitEthernet2/2 Backup O E2 [110/1] via 10.12.12.2, POS3/0 Output of show route best-local Command: Example The following is sample output from the show route best-local command: RP/0/RP0/CPU0:router# show route best-local 10.12.12.1 Routing entry for 10.12.12.1/32 Known via "local", distance 0, metric 0 (connected) Routing Descriptor Blocks 10.12.12.1 directly connected, via POS3/0 Route metric is 0 Output of show route connected Command: Example The following is sample output from the show route connected command: RP/0/RP0/CPU0:router# show route connected Gateway of last resort is 172.23.54.1 to network 0.0.0.0 C C C 10.2.210.0/24 is directly connected, 1d21h, Ethernet0 172.20.16.0/24 is directly connected, 1d21h, ATM4/0.1 10.6.100.0/24 is directly connected, 1d21h, Loopback1 Output of show route local Command: Example The following is sample output from the show route local command: RP/0/RP0/CPU0:router# show route local L L L 10.10.10.1/32 is directly connected, 00:14:36, Loopback0 10.91.36.98/32 is directly connected, 00:14:32, Ethernet0/0 172.22.12.1/32 is directly connected, 00:13:35, POS3/0 Cisco IOS XR Routing Configuration Guide RC-201 Implementing and Monitoring RIB on Cisco IOS XR Software Where to Go Next L L 192.168.20.2/32 is directly connected, 00:13:27, GigabitEthernet2/0 10.254.254.1/32 is directly connected, 00:13:26, GigabitEthernet2/2 Output of show route longer-prefixes Command: Example The following is sample output from the show route longer-prefixes command: RP/0/RP0/CPU0:router# show route ipv4 172.16.0.0/8 longer-prefixes Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP O - OSPF, IA - OSPF inter area, N1 - OSPF NSSA external type 1 N2 - OSPF NSSA external type 2, E1 - OSPF external type 1 E2 - OSPF external type 2, E - EGP, i - ISIS, L1 - IS-IS level-1 L2 - IS-IS level-2, ia - IS-IS inter area su - IS-IS summary null, * - candidate default U - per-user static route, o - ODR, L - local Gateway of last resort is 172.23.54.1 to network 0.0.0.0 S 172.16.2.0/32 is directly connected, 00:00:24, Loopback0 S 172.16.3.0/32 is directly connected, 00:00:24, Loopback0 S 172.16.4.0/32 is directly connected, 00:00:24, Loopback0 S 172.16.5.0/32 is directly connected, 00:00:24, Loopback0 S 172.16.6.0/32 is directly connected, 00:00:24, Loopback0 S 172.16.7.0/32 is directly connected, 00:00:24, Loopback0 S 172.16.8.0/32 is directly connected, 00:00:24, Loopback0 S 172.16.9.0/32 is directly connected, 00:00:24, Loopback0 Output of show route next-hop Command: Example The following is sample output from the show route next-hop command: RP/0/RP0/CPU0:router# show route next-hop 10.0.0.1 Routing entry for 10.0.0.0/24 Known via "connected", distance 0, metric 0 (connected) Routing Descriptor Blocks 10.0.0.50 directly connected, via GigabitEthernet6/0 Route metric is 0 Where to Go Next For additional information on the protocols that interact with RIB, you may want to see the following publications: • Implementing BGP on Cisco IOS XR Software • Implementing IS-IS on Cisco IOS XR Software • Implementing OSPF on Cisco IOS XR Software • RIB Commands on Cisco IOS XR Software Cisco IOS XR Routing Configuration Guide RC-202 Implementing and Monitoring RIB on Cisco IOS XR Software Additional References Additional References The following sections provide references related to implementing RIB on Cisco IOS XR software: Related Documents Related Topic Document Title Routing Information Base commands: complete RIB Commands on Cisco IOS XR Software in the Cisco IOS XR command syntax, command modes, command history, Routing Command Reference, Release 3.2 defaults, usage guidelines, and examples BGP commands: complete command syntax, command BGP Commands on Cisco IOS XR Software, in the Cisco IOS XR modes, command history, defaults, usage guidelines, Routing Command Reference, Release 3.2 and examples IS-IS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples IS-IS Commands on Cisco IOS XR Software in the Cisco IOS XR Routing Command Reference, Release 3.2 OSPF commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples OSPF Commands on Cisco IOS XR Software in the Cisco IOS XR Routing Command Reference, Release 3.2 OSPFv3 commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples OSPFv3 Commands on Cisco IOS XR Software in the Cisco IOS XR Routing Command Reference, Release 3.2 Multicast commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples Cisco IOS XR Multicast Command Reference, Release 3.2 Multicast configuration: complete command syntax, command modes, command history, defaults, usage guidelines, and examples Cisco IOS XR Multicast Configuration Guide, Release 3.2 Standards Standards Title No new or modified standards are supported by this — feature, and support for existing standards has not been modified by this feature. MIBs MIBs • IP-FORWARD-MIB • RFC1213-MIB MIBs Link To locate and download MIBs for selected platforms using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL: http://cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml Cisco IOS XR Routing Configuration Guide RC-203 Implementing and Monitoring RIB on Cisco IOS XR Software Additional References RFCs RFCs Title No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. — Technical Assistance Description Link http://www.cisco.com/techsupport The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content. Cisco IOS XR Routing Configuration Guide RC-204 Implementing Routing Policy on Cisco IOS XR Software A routing policy instructs the router to inspect routes, filter them, and potentially modify their attributes as they are accepted from a peer, advertised to a peer, or redistributed from one routing protocol to another. Routing protocols make decisions to advertise, aggregate, discard, distribute, export, hold, import, redistribute and otherwise modify routes based on configured routing policy. The routing policy language (RPL) has been designed to provide a single, straightforward language in which all routing policy needs can be expressed. RPL was designed to support large-scale routing configurations. It greatly reduces the redundancy inherent in previous routing policy configuration methods. RPL has been designed to streamline routing policy configuration, to reduce system resources required to store and process these configurations, and to simplify troubleshooting. Note For more information about routing policy on the Cisco IOS XR software and complete descriptions of the routing policy commands listed in this module, see the “Related Documents” section of this module. To locate documentation for other commands that might appear during execution of a configuration task, search online in the Cisco IOS XR software master command index. Feature History for Implementing Routing Policy on Cisco IOS XR Software Release Modification Release 2.0 This feature was introduced on the Cisco CRS-1. Release 3.0 No modification. Release 3.2 Support was added for the Cisco XR 12000 Series Router. Contents • Prerequisites for Implementing Routing Policy, page RC-206 • Information About Implementing Routing Policy, page RC-206 • How to Implement Routing Policy, page RC-237 • Configuration Examples for Implementing Routing Policy, page RC-241 • Additional References, page RC-244 Cisco IOS XR Routing Configuration Guide RC-205 Implementing Routing Policy on Cisco IOS XR Software Prerequisites for Implementing Routing Policy Prerequisites for Implementing Routing Policy The following are prerequisites for implementing Routing Policy on Cisco IOS XR Software: • To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide. • Border Gateway Protocol (BGP), integrated Intermediate System-to-Intermediate System (IS-IS), or Open Shortest Path First (OSPF) must be configured in your network. Information About Implementing Routing Policy To implement RPL, you need to understand the following concepts: • Routing Policy Language, page RC-206 • Routing Policy Language, page RC-206 • Routing Policy Configuration Basics, page RC-213 • Policy Definitions, page RC-213 • Parameterization, page RC-214 • Semantics of Policy Application, page RC-215 • Policy Statements, page RC-219 • Attach Points, page RC-223 • Attached Policy Modification, page RC-235 • Nonattached Policy Modification, page RC-235 Routing Policy Language This section contains the following information: • Routing Policy Language Overview, page RC-206 • Routing Policy Language Structure, page RC-207 • Routing Policy Language Components, page RC-211 • Routing Policy Language Usage, page RC-211 Routing Policy Language Overview RPL was developed to support large-scale routing configurations. RPL has several fundamental capabilities that differ from those present in configurations oriented to traditional route maps, access lists, and prefix lists. The first of these capabilities is the ability to build policies in a modular form. Common blocks of policy can be defined and maintained independently. These common blocks of policy can then be applied from other blocks of policy to build complete policies. This capability reduces the amount of configuration information that needs to be maintained. In addition, these common blocks of policy can be parameterized. This parameterization allows for policies that share the same structure but differ in the specific values that are set or matched against to be maintained as independent blocks of Cisco IOS XR Routing Configuration Guide RC-206 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy policy. For example, three policies that are identical in every way except for the local preference value they set can be represented as one common parameterized policy that takes the varying local preference value as a parameter to the policy. The policy language introduces the notion of sets. Sets are containers of similar data that can be used in route attribute matching and setting operations. Four set types exist: prefix-sets, community-sets, as-path-sets, and extcommunity-sets. These sets hold groupings of IPv4 or IPv6 prefixes, community values, AS path regular expressions, and extended community values, respectively. Sets are simply containers of data. Most sets also have an inline variant. An inline set allows for small enumerations of values to be used directly in a policy rather than having to refer to a named set. Prefix lists, community lists, and AS path lists must be maintained even when only one or two items are in the list. An inline set in RPL allows the user to place small sets of values directly in the policy body without having to refer to a named set. Decision making, such as accept and deny, is explicitly controlled by the policy definitions themselves. RPL combines matching operators, which may use set data, with the traditional Boolean logic operators and, or, and not into complex conditional expressions. All matching operations return a true or false result. The execution of these conditional expressions and their associated actions can then be controlled by using simple if then, elseif, and else structures, which allow the evaluation paths through the policy to be fully specified by the user. Routing Policy Language Structure This section describes the basic structure of RPL. Names The policy language provides two kinds of persistent, namable objects: sets and policies. Definition of these objects is bracketed by beginning and ending command lines. For example, to define a policy named test, the configuration syntax would look similar to the following: route-policy test [ . . . policy statements . . . ] end-policy Legal names for policy objects can be any sequence of the upper- and lowercase alphabetic characters; the numerals 0 to 9; and the punctuation characters period, hyphen, and underscore. A name must begin with a letter or numeral. Sets In this context, the term set is used in its mathematical sense to mean an unordered collection of unique elements. The policy language provides sets as a container for groups of values for matching purposes. Sets are used in conditional expressions. The elements of the set are separated by commas. Null (empty) sets are not allowed. Four kinds of sets exist: as-path-set, community-set, extcommunity-set, and prefix-set. You may want to perform comparisons against a small number of elements, such as two or three community values, for example. To allow for these comparisons, the user can enumerate these values directly. These enumerations are referred to as inline sets. Functionally, inline sets are equivalent to named sets, but allow for simple tests to be inline. Thus, comparisons do not require that a separate named set be maintained when only one or two elements are being compared. See the set types described in the following sections for the syntax. In general, the syntax for an inline set is a comma-separated list Cisco IOS XR Routing Configuration Guide RC-207 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy surrounded by parentheses as follows: ( , , , ... ), where is an entry of an item appropriate to the type of usage such as a prefix or a community value. The following is an example using an inline community set: route-policy sample-inline if community matches-any ([10..15]:100) then set local-preference 100 endif end-policy The following is an equivalent example using the named set test-communities: community-set test-communities 10:100, 11:100, 12:100, 13:100, 14:100, 15:100 end-set route-policy sample if community matches-any test-communities then set local-preference 100 endif end-policy Both of these policies are functionally equivalent, but the inline form does not require the configuration of the community set just to store the six values. You can choose the form appropriate to the configuration context. In the following sections, examples of both the named set version and the inline form are provided where appropriate. as-path-set An AS path set comprises operations for matching an AS path attribute. The only matching operation is a regular expression match. Named Set Form The named set form uses the ios-regex keyword to indicate the type of regular expression and requires single quotation marks around the regular expression. The following is a sample definition of a named AS path set: as-path-set aset1 ios-regex ’_42$’, ios-regex ’_127$’ end-set This AS path set comprises two elements. When used in a matching operation, this AS path set matches any route whose AS path ends with either the autonomous system (AS) number 42 or 127. To remove the named AS path set, use the no as-path-set aset1 command-line interface (CLI) command. Inline Set Form The inline set form is a parenthesized list of comma-separated expressions, as follows: (ios-regex '_42$', ios-regex '_127$') Cisco IOS XR Routing Configuration Guide RC-208 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy This set matches the same AS paths as the previously named set, but does not require the extra effort of creating a named set separate from the policy that uses it. community-set A community-set holds community values for matching against the BGP community attribute. A community is a 32-bit quantity. Integer community values must be split in half and expressed as two unsigned decimal integers in the range from 0 to 65535, separated by a colon. Single 32-bit community values are not allowed. The following is the named set form: Named Set Form community-set cset1 12:34, 12:56, 12:78, internet end-set Inline Set Form (12:34, 12:56, 12:78) ($as:34, $as:$tag1, 12:78, internet) The inline form of a community-set also supports parameterization. Each 16-bit portion of the community may be parameterized. See the “Parameterization” section on page RC-214 for more information. RPL provides symbolic names for the standard well-known community values: internet is 0:0, no-export is 65535:65281, no-advertise is 65535:65282, and local-as is 65535:65283. RPL also provides a facility for using wildcards in community specifications. A wildcard is specified by inserting an asterisk (*) in place of one of the 16-bit portions of the community specification; the wildcard indicates that any value for that portion of the community matches. Thus, the following policy matches all communities in which the autonomous system part of the community is 123: community-set cset3 123:* end-set Every community set must contain at least one community value. Empty community sets are invalid and are rejected. extcommunity-set An extended community-set is analogous to a community-set except that it contains extended community values instead of regular community values. It also supports named forms and inline forms. The following are syntactic examples: Named Form extcommunity-set extcomm-set1 RT:1.2.3.4:666, RT:1234:666, SoO:1.2.3.4:777, SoO :4567:777 end-set Cisco IOS XR Routing Configuration Guide RC-209 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy Inline Form (RT:1.2.3.4:666, RT:1234:6667, SoO:1.2.3.4:777, SoO:45678:777) (RT:$ipaddr:666, RT:1234:$tag, SoO:1.2.3.4:777, SoO:$tag2:777) As with community sets, the inline form supports parameterization within parameterized policies. Either portion of the extended community value can be parameterized. Every extended community-set must contain at least one extended community value. Empty extended community-sets are invalid and rejected. prefix-set A prefix-set holds IPv4 or IPv6 prefix match specifications, each of which has four parts: an address, a mask length, a minimum matching length, and a maximum matching length. The address is required, but the other three parts are optional. The address is a standard dotted-decimal IPv4 or colon-separated hexadecimal IPv6 address. The mask length, if present, is a nonnegative decimal integer in the range from 0 to 32 (0 to 128 for IPv6) following the address and separated from it by a slash. The optional minimum matching length follows the address and optional mask length and is expressed as the keyword ge (mnemonic for greater than or equal to), followed by a nonnegative decimal integer in the range from 0 to 32 (0 to 128 for IPv6). The optional maximum matching length follows the rest and is expressed by the keyword le (mnemonic for less than or equal to), followed by yet another nonnegative decimal integer in the range from 0 to 32 (0 to 128 for IPv6). A syntactic shortcut for specifying an exact length for prefixes to match is the eq keyword (mnemonic for equal to). If a prefix match specification has no mask length, then the default mask length is 32 for IPv4 and 128 for IPv6. The default minimum matching length is the mask length. If a minimum matching length is specified, then the default maximum matching length is 32 for IPv4 and 128 for IPv6. Otherwise, if neither minimum nor maximum is specified, the default maximum is the mask length. The prefix-set itself is a comma-separated list of prefix match specifications. The following are examples: prefix-set legal-ipv4-prefix-examples 10.0.1.1, 10.0.2.0/24, 10.0.3.0/24 ge 28, 10.0.4.0/24 le 28, 10.0.5.0/24 ge 26 le 30, 10.0.6.0/24 eq 28 end-set prefix-set legal-ipv6-prefix-examples 2001:0:0:1::/64, 2001:0:0:2::/64 ge 96, 2001:0:0:2::/64 ge 96 le 100, 2001:0:0:2::/64 eq 100 end-set The first element of the prefix-set matches only one possible value, 10.0.1.1/32 or the host address 10.0.1.1. The second element matches only one possible value, 10.0.2.0/24. The third element matches a range of prefix values, from 10.0.3.0/28 to 10.0.3.255/32. The fourth element matches a range of values, from 10.0.4.0/24 to 10.0.4.240/28. The fifth element matches prefixes in the range from 10.0.5.0/26 to 10.0.5.252/30. The sixth element matches any prefix of length 28 in the range from 10.0.6.0/28 through 10.0.6.240/28. Cisco IOS XR Routing Configuration Guide RC-210 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy The following prefix-set consists entirely of invalid prefix match specifications: prefix-set ILLEGAL-PREFIX-EXAMPLES 10.1.1.1 ge 16, 10.1.2.1 le 16, 10.1.3.0/24 le 23, 10.1.4.0/24 ge 33, 10.1.5.0/25 ge 29 le 28 end-set Neither the minimum length nor maximum length is valid without a mask length. The maximum length must be at least the mask length. For IPv4, the minimum length must be less than 32, the maximum length of an IPv4 prefix. For IPv6, the minimum length must be less than 128, the maximum length of an IPv6 prefix. The maximum length must be equal to or greater than the minimum length. Routing Policy Language Components Four main components in the routing policy language are involved in defining, modifying, and using policies: the configuration front end, policy repository, execution engine, and policy clients themselves. The configuration front end (CLI) is the mechanism to define and modify policies. This configuration is then stored on the router using the normal storage means and can be displayed using the normal configuration show commands. The second component of the policy infrastructure, the policy repository, has several responsibilities. First, it compiles the user-entered configuration into a form that the execution engine can understand. Second, it performs much of the verification of policies; and it ensures that defined policies can actually be executed properly. Third, it tracks which attach points are using which policies so that when policies are modified the appropriate clients are properly updated with the new policies relevant to them. The third component is the execution engine. This component is the piece that actually runs policies as the clients request. The process can be thought of as receiving a route from one of the policy clients and then executing the actual policy against the specific route data. The fourth component is the policy clients (the routing protocols). This component calls the execution engine at the appropriate times to have a given policy be applied to a given route, and then perform some number of actions. These actions may include deleting the route if policy indicated that it should be dropped, passing along the route to the protocol decision tree as a candidate for the best route, or advertising a policy modified route to a neighbor or peer as appropriate. Routing Policy Language Usage This section provides basic routing policy language usage examples. See the “How to Implement Routing Policy” section on page RC-237 for detailed information on how to implement routing policy language. The pass policy The following example shows how the policy accepts all presented routes without modifying the routes. route-policy quickstart-pass pass end-policy The drop everything policy The following example shows how the policy explicitly rejects all routes presented to it. This type of policy is used to ignoring everything coming from a misbehaving peer. Cisco IOS XR Routing Configuration Guide RC-211 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy route-policy quickstart-drop drop end-policy Ignore routes with specific AS numbers in the path The following example shows the policy definition in three parts. First, the as-path-set command defines three regular expressions to match against an AS path. Second, the route-policy command applies the AS path set to a route. If the AS path attribute of the route matches the regular expression defined with the as-path-set command, the protocol refuses the route. Third, the route policy is attached to BGP neighbor 10.0.1.2. BGP consults the policy named ignore_path_as on routes received (imported) from neighbor 10.0.1.2. as-path-set ignore_path ios-regex '_11_', ios-regex '_22_', ios-regex '_33_' end-set route-policy ignore_path_as if as-path in ignore_path then drop else pass endif end-policy router bgp 2 neighbor 10.0.1.2 address-family ipv4 unicast policy ignore_path_as in Set community based on MED The following example shows how the policy tests the MED of a route and modifies the community attribute of the route based on the value of the MED. If the MED value is 127, the policy adds the community 123:456 to the route. If the MED value is 63, the policy adds the value 123:789 to the community attribute of the route. Otherwise, the policy removes the community 123:123 from the route. In any case, the policy instructs the protocol to accept the route. route-policy quickstart-med if med eq 127 then set community (123:456) additive elseif med eq 63 then set community (123:789) additive else delete community in (123:123) endif pass end-policy Set local preference based on community The following example shows how the community-set named quickstart-communities defines community values. The route policy named quickstart-localpref tests a route for the presence of the communities specified in the quickstart-communities community set. If any of the community values are present in the route, the route policy sets the local preference attribute of the route to 31. In any case, the policy instructs the protocol to accept the route. community-set quickstart-communities 987:654, 987:543, 987:321, 987:210 end-set Cisco IOS XR Routing Configuration Guide RC-212 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy route-policy quickstart-localpref if community matches-any quickstart-communities then set local-preference 31 endif pass end-policy Persistent Remarks The following example shows how comments are placed in the policy to clarify the meaning of the entries in the set and the statements in the policy. The remarks are persistent, meaning they remain attached to the policy. For example, remarks are displayed in the output of the show running-config command. Adding remarks to the policy makes the policy easier to understand, modify at a later date, and troubleshoot if an unexpected behavior occurs. prefix-set rfc1918 # These are the networks defined as private in RFC1918 (including # all subnets thereof) 10.0.0.0/8 ge 8, 172.16.0.0/12 ge 12, 192.168.0.0/16 ge 16 end-set route-policy quickstart-remarks # Handle routes to RFC1918 networks if destination in rfc1918 then # Set the community such that we do not export the route set community (no-export) additive endif end-policy Routing Policy Configuration Basics Route policies comprise series of statements and expressions that are bracketed with the route-policy and end-policy keywords. Rather than a collection of individual commands (one for each line), the statements within a route policy have context relative to each other. Thus, instead of each line being an individual command, each policy or set is an independent configuration object that can be used, entered, and manipulated as a unit. Each line of a policy configuration is a logical subunit. At least one new line must follow the then, else, and end-policy keywords. A new line must also follow the closing parenthesis of a parameter list and the name string in a reference to an AS path set, community set, extended community set, or prefix set. At least one new line must precede the definition of a route policy, AS path set, community set, extended community set, or prefix set. One or more new lines can follow an action statement. One or more new lines can follow a comma separator in a named AS path set, community set, extended community set, or prefix set. A new line must appear at the end of a logical unit of policy expression and may not appear anywhere else. Policy Definitions Policy definitions create named sequences of policy statements. A policy definition consists of the CLI route-policy keyword followed by a name, a sequence of policy statements, and the end-policy keyword. For example, the following policy drops any route it encounters: Cisco IOS XR Routing Configuration Guide RC-213 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy route-policy drop-everything drop end-policy The name serves as a handle for binding the policy to protocols. To remove a policy definition, issue the no route-policy name command. Policies may also refer to other policies such that common blocks of policy can be reused. This reference to other policies is accomplished by using the apply statement, as shown in the following example: route-policy check-as-1234 if as-path passes-through ‘1234’ then apply drop-everything else pass endif end-policy The apply statement indicates that the policy drop-everything should be executed if the route under consideration passed through autonomous system 1234 before it is received. If a route that has autonomous system 1234 in its AS path is received, the route is dropped; otherwise, the route is accepted without modification. This policy is an example of a hierarchical policy. Thus, the semantics of the apply statement are just as if the applied policy were cut and pasted into the applying policy: route-policy check-as-1234-prime if as-path passes-through '1234' then drop else pass endif end-policy You may have as many levels of hierarchy as desired. However, many levels may be difficult to maintain and understand. Parameterization In addition to supporting reuse of policies using the apply statement, policies can be defined that allow for parameterization of some of the attributes. The following example shows how to define a parameterized policy named param-example. In this case, the policy takes one parameter, $mytag. Parameters always begin with a dollar sign and consist otherwise of any alphanumeric characters. Parameters can be substituted into any attribute that takes a parameter. In the following example, a 16-bit community tag is used as a parameter: route-policy param-example ($mytag) set community (1234:$mytag) additive end-policy This parameterized policy can then be reused with different parameterizations, as shown in the following example. In this manner, policies that share a common structure but use different values in some of their individual statements can be modularized. For details on which attributes can be parameterized, see the individual attribute sections. Cisco IOS XR Routing Configuration Guide RC-214 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy route-policy origin-10 if as-path originates-from ‘10’ then apply param-example(10) else pass endif end-policy route-policy origin-20 if as-path originates-from ‘20’ then apply param-example(20) else pass endif end-policy The parameterized policy param-example provides a policy definition that is expanded with the values provided as the parameters in the apply statement. Note that the policy hierarchy is always maintained, Thus, if the definition of param-example changes, then the behavior of origin_10 and origin_20 changes to match. The effect of the origin-10 policy is that it adds the community 1234:10 to all routes that pass through this policy and have an AS path indicating the route originated from autonomous system 10. The origin-20 policy is similar except that it adds to community 1234:20 for routes originating from autonomous system 20. Semantics of Policy Application This section discusses how routing policies are evaluated and applied. The following concepts are discussed: • Boolean Operator Precedence, page RC-215 • Multiple Modifications of the Same Attribute, page RC-216 • When Attributes Are Modified, page RC-216 • Default Drop Disposition, page RC-217 • Control Flow, page RC-217 • Policy Verification, page RC-218 Boolean Operator Precedence Boolean expressions are evaluated in order of operator precedence, from left to right. The highest precedence operator is not, followed by and, and then or. The following expression: med eq 10 and not destination in (10.1.3.0/24) or community matches-any ([10..25]:35) if fully parenthesized to display the order of evaluation, would look like this: (med eq 10 and (not destination in (10.1.3.0/24))) or community matches-any ([10..25]:35) The inner not applies only to the destination test; the and combines the result of the not expression with the Multi Exit Discriminator (MED) test; and the or combines that result with the community test. If the order of operations are rearranged: not med eq 10 and destination in (10.1.3.0/24) or community matches-any ([10..25]:35) Cisco IOS XR Routing Configuration Guide RC-215 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy then the expression, fully parenthesized, would look like the following: ((not med eq 10) and destination in (10.1.3.0/24)) or community matches-any ([10..25]:35) Multiple Modifications of the Same Attribute When a policy replaces the value of an attribute multiple times, the last assignment wins because all actions are executed. Because the MED attribute in BGP is one unique value, the last value to which it gets set to wins. Therefore, the following policy results in a route with a MED value of 12: set set set set med med med med 9 10 11 12 This example is trivial, but the feature is not. It is possible to write a policy that effectively changes the value for an attribute. For example: set med 8 if community matches-any cs1 then set local-preference 122 if community matches-any cs2 then set med 12 endif endif The result is a route with a MED of 8, unless the community list of the route matches both cs1 and cs2, in which case the result is a route with a MED of 12. In the case in which the attribute being modified can contain only one value, it is easy to think of this case as the last statement wins. However, a few attributes can contain multiple values and the result of multiple actions on the attribute is cumulative rather than as a replacement. The first of these cases is the use of the additive keyword on community and extended community evaluation. Consider a policy of the form: route-policy community-add set community (10:23) set community (10:24) additive set community (10:25) additive end-policy This policy sets the community string on the route to contain all three community values: 10:23, 10:24, and 10:25. The second of these cases is AS path prepending. Consider a policy of the form: route-policy prepend-example prepend as-path 2 3 prepend as-path 666 2 end-policy This policy prepends the following to the AS path (666 666 2 2 2). This prepending is a result of all actions being taken and to AS path being an attribute that contains an array of values rather than a simple scalar value. When Attributes Are Modified A policy does not modify route attribute values until all tests have been completed. In other words, comparison operators always run on the initial data in the route. Intermediate modifications of the route attributes do not have a cascading effect on the evaluation of the policy. Take the following example: Cisco IOS XR Routing Configuration Guide RC-216 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy if med eq 12 then set med 42 if med eq 42 then drop endif endif This policy never executes the drop statement because the second test (med eq 42) sees the original, unmodified value of the MED in the route. Because the MED has to be 12 to get to the second test, the second test always returns false. Default Drop Disposition All route policies have a default action to drop the route under evaluation unless the route has been modified by a policy action or explicitly passed. Applied (nested) policies implement this disposition as though the applied policy were pasted into the point where it is applied. Consider a policy to allow all routes in the 10 network and set their local preference to 200 while dropping all other routes. You might write the policy as follows: route-policy two if destination in (10.0.0.0/8 ge 8 le 32) then set local-preference 200 endif end-policy route-policy one apply two end-policy It may appear that policy one drops all routes because it neither contains an explicit pass statement nor modifies a route attribute. However, the applied policy does set an attribute for some routes and this disposition is passed along to policy one. The result is that policy one passes routes with destinations in network 10, and drops all others. Control Flow Policy statements are processed sequentially in the order in which they appear in the configuration. Policies that hierarchically reference other policy blocks are processed as if the referenced policy blocks had been directly substituted inline. For example, if the following policies are defined: route-policy one set weight 100 end-policy route-policy two set med 200 end-policy route-policy three apply two set community (2:666) additive end-policy route-policy four apply one apply three pass end-policy Cisco IOS XR Routing Configuration Guide RC-217 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy Policy four could be rewritten in an equivalent way as follows: route-policy four-equivalent set weight 100 set med 200 set community (2:666) additive pass end-policy Note The pass statement is not required and can be removed to represent the equivalent policy in another way. Policy Verification Several different types of verification occur when policies are being defined and used. Range Checking As policies are being defined, some simple verifications, such as range checking of values, is done. For example, the MED that is being set is checked to verify that it is in a proper range for the MED attribute. However, this range checking cannot cover parameter specifications because they may not have defined values yet. These parameter specifications are verified when a policy is attached to an attach point. The policy repository also verifies that there are no recursive definitions of policy, and that parameter numbers are correct. At attach time, all policies must be well formed. All sets and policies that they reference must be defined and have valid values. Likewise, any parameter values must also be in the proper ranges. Incomplete Policy and Set References As long as a given policy is not attached at an attach point, the policy is allowed to refer to nonexistent sets and policies, which allows for freedom of workflow. You can build configurations that reference sets or policy blocks that are not yet defined, and then can later fill in those undefined policies and sets, thereby achieving much greater flexibility in policy definition. Every piece of policy you want to reference while defining a policy need not exist in the configuration. Thus, a user can define a policy sample that references the policy bar using an apply statement even if the policy bar does not exist. Similarly, a user can enter a policy statement that refers to a nonexistent set. However, the existence of all referenced policies and sets is enforced when a policy is attached. If you attempt to attach the policy sample with the reference to an undefined policy bar at an inbound BGP policy using the neighbor 1.2.3.4 address-family ipv4 unicast policy sample in command, the configuration attempt is rejected because the policy bar does not exist. Likewise, you cannot remove a route policy or set that is currently in use at an attach point because this removal would result in an undefined reference. An attempt to remove a route policy or set that is currently in use results in an error message to the user. A condition exists that is referred to as a null policy in which the policy bar exists but has no statements, actions, or dispositions in it. In other words, the policy bar does exist as follows: route-policy bar end-policy This is a valid policy block. It effectively forces all routes to be dropped because it is a policy block that never modifies a route, nor does it include the pass statement. Thus, the default action of drop for the policy block is followed. Cisco IOS XR Routing Configuration Guide RC-218 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy Attached Policy Modification Policies that are in use do, on occasion, need to be modified. Traditionally, configuration changes are done by completely removing the relevant configuration and then re-entering it. However, this allows for a window of time in which no policy is attached and the default action takes place. RPL provides a mechanism for an atomic change so that if a policy is redeclared, or edited using the emacs editor, the new configuration is applied immediately, which allows for policies that are in use to be changed without having a window of time in which no policy is applied at the given attach point. Verification of Attribute Comparisons and Actions The policy repository knows which attributes, actions, and comparisons are valid at each attach point. When a policy is attached, these actions and comparisons are verified against the capabilities of that particular attach point. Take, for example, the following policy definition: route-policy bad set med 100 set level level-1-2 set cost 200 end-policy This policy attempts to perform actions to set the BGP attribute med, IS-IS attribute level, and OSPF attribute cost. The system allows you to define such a policy, but it does not allow you to attach such a policy. If you had defined the policy bad and then attempted to attach it as an inbound BGP policy using the BGP configuration statement neighbor 1.2.3.4 address-family ipv4 unicast route-policy bad in the system would reject this configuration attempt. This rejection results from the verification process checking the policy and realizing that while BGP could set the MED, it has no way of setting the level or cost as the level and cost are attributes of IS-IS and OSPF, respectively. Instead of silently omitting the actions that cannot be done, the system generates an error to the user. Likewise, a valid policy in use at an attach point cannot be modified in such a way as to introduce an attempt to modify a nonexistent attribute or to compare against a nonexistent attribute. The verifiers test for nonexistent attributes and reject such a configuration attempt. Policy Statements Four types of policy statements exist: remark, disposition (drop and pass), action (set), and if (comparator). Remark A remark is text attached to policy configuration but otherwise ignored by the policy language parser. Remarks are useful for documenting parts of a policy. The syntax for a remark is text that has each line prepended with a pound sign (#): # This is a simple one-line remark. # # # # This is a remark comprising multiple lines. In general, remarks are used between complete statements or elements of a set. Remarks are not supported in the middle of statements or within an inline set definition. Cisco IOS XR Routing Configuration Guide RC-219 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy Unlike traditional !-comments in the CLI, RPL remarks persist through reboots and when configurations are saved to disk or a TFTP server and then loaded back onto the router. Disposition By default, a route is dropped at the end of policy processing unless either the policy modifies a route attribute or it passes the route by means of an explicit pass statement. For example, the following policy drops all routes because it neither modifies the attribute of any route nor explicitly passes it. route-policy EMPTY end-policy Whereas the following policies pass all routes that they evaluate. route-policy PASS-ALL pass end-policy route-policy SET-LPREF set local-preference 200 end-policy In addition to being implicitly dropped, a route may be dropped by an explicit drop statement. Drop statements cause a route to be dropped immediately so that no further policy processing is done. Note also that a drop statement overrides any previously processed pass statements or attribute modifications. For example, the following policy drops all routes. The first pass statement is executed, but is then immediately overridden by the drop statement. The second pass statement never gets executed. route-policy DROP-EXAMPLE pass drop pass end-policy When one policy applies another, it is as if the applied policy were copied into the right place in the applying policy, and then the same drop-and-pass semantics are put into effect. For example, policies ONE and TWO are equivalent to policy ONE-PRIME: route-policy ONE apply route-policy two if as-path neighbor-is '123' then pass endif end-policy route-policy TWO if destination in (10.0.0.0/16 le 32) then drop endif end-policy route-policy ONE-PRIME if destination in (10.0.0.0/16 le 32) then drop endif if as-path neighbor-is '123' then pass endif end-policy Cisco IOS XR Routing Configuration Guide RC-220 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy Because the effect of an explicit drop statement is immediate, routes in 10.0.0.0/16 le 32 are dropped without any further policy processing. Other routes are then considered to see if they were advertised by autonomous system 123. If they were advertised, they are passed; otherwise, they are implicitly dropped at the end of all policy processing. Action An action is a sequence of primitive operations that modify a route. Most actions, but not all, are distinguished by the set keyword. In a route policy, actions can be grouped together. For example, the following is a route policy comprising three actions: route-policy actions set med 217 set community (12:34) additive delete community in (12:56) end-policy If In its simplest form, an if statement uses a conditional expression to decide which actions or dispositions should be taken for the given route. For example: if as-path in as-path-set-1 then drop endif The example indicates that any routes whose AS path is in the set as-path-set-1 are dropped. The contents of the then clause may be an arbitrary sequence of policy statements. The following example contains two action statements: if origin is igp then set med 42 prepend as-path 73 5 endif The CLI provides support for the exit command as an alternative to the endif command. The if statement also permits an else clause, which is executed if the if condition is false: if med eq 8 then set community (12:34) additive else set community (12:56) additive endif The policy language also provides syntax, using the elseif keyword, to string together a sequence of tests: if med eq 150 then set local-preference elseif med eq 200 then set local-preference elseif med eq 250 then set local-preference else set local-preference endif 10 60 110 0 Cisco IOS XR Routing Configuration Guide RC-221 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy The statements within an if statement may themselves be if statements, as shown in the following example: if community matches-any (12:34,56:78) then if med eq 150 then drop endif set local-preference 100 endif This policy example sets the value of the local preference attribute to 100 on any route that has a community value of 12:34 or 56:78 associated with it. However, if any of these routes has a MED value of 150, then these routes with either the community value of 12:34 or 56:78 and a MED of 150 are dropped. Boolean Conditions In the previous section describing the if statement, all of the examples use simple Boolean conditions that evaluate to either true or false. RPL also provides a way to build compound conditions from simple conditions by means of Boolean operators. Three Boolean operators exist: negation (not), conjunction (and), and disjunction (or). In the policy language, negation has the highest precedence, followed by conjunction, and then by disjunction. Parentheses may be used to group compound conditions to override precedence or to improve readability. The following simple condition: med eq 42 is true only if the value of the MED in the route is 42, otherwise it is false. A simple condition may also be negated using the not operator: not next-hop in (10.0.2.2) Any Boolean condition enclosed in parentheses is itself a Boolean condition: (destination in prefix-list-1) A compound condition takes either of two forms. It can be a simple expression followed by the and operator, itself followed by a simple condition: med eq 42 and next-hop in (10.0.2.2) A compound condition may also be a simpler expression followed by the or operator and then another simple condition: origin is igp or origin is incomplete An entire compound condition may be enclosed in parentheses: (med eq 42 and next-hop in (10.0.2.2)) The parentheses may serve to make the grouping of subconditions more readable, or they may force the evaluation of a subcondition as a unit. In the following example, the highest-precedence not operator applies only to the destination test, the and operator combines the result of the not expression with the community test, and the or operator combines that result with the MED test. med eq 10 or not destination in (10.1.3.0/24) and community matches-any ([12..34]:[56..78]) Cisco IOS XR Routing Configuration Guide RC-222 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy With a set of parentheses to express the precedence, the result is the following: med eq 10 or ((not destination in (10.1.3.0/24)) and community matches-any ([12..34]:[56..78]) The following is another example of a complex expression: (origin is igp or origin is incomplete or not med eq 42) and next-hop in (10.0.2.2) The left conjunction is a compound condition enclosed in parentheses. The first simple condition of the inner compound condition tests the value of the origin attribute; if it is Interior Gateway Protocol (IGP), then the inner compound condition is true. Otherwise, the evaluation moves on to test the value of the origin attribute again, and if it is incomplete, then the inner compound condition is true. Otherwise, the evaluation moves to check the next component condition, which is a negation of a simple condition. apply As discussed in the sections on policy definitions and parameterization of policies, the apply command executes another policy (either parameterized or unparameterized) from within another policy, which allows for the reuse of common blocks of policy. When combined with the ability to parameterize common blocks of policy, the apply command becomes a powerful tool for reducing repetitive configuration. Attach Points Policies do not become useful until they are applied to routes, and for policies to be applied to routes they need to be made known to routing protocols. In BGP, for example, there are several situations where policies can be used, the most common of these is defining import and export policy. The policy attach point is the point in which an association is formed between a specific protocol entity, in this case a BGP neighbor, and a specific named policy. It is important to note that a verification step happens at this point. Each time a policy is attached, the given policy and any policies it may apply are checked to ensure that the policy can be validly used at that attach point. For example, if a user defines a policy that sets the IS-IS level attribute and then attempts to attach this policy as an inbound BGP policy, the attempt would be rejected because BGP routes do not carry IS-IS attributes. Likewise, when policies are modified that are in use, the attempt to modify the policy is verified against all current uses of the policy to ensure that the modification is compatible with the current uses. Each protocol has a distinct definition of the set of attributes (commands) that compose a route. For example, BGP routes may have a community attribute, which is undefined in OSPF. Routes in IS-IS have a level attribute, which is unknown to BGP. Routes carried internally in the RIB may have a tag attribute. When a policy is attached to a protocol, the protocol checks the policy to ensure the policy operates using route attributes known to the protocol. If the protocol uses unknown attributes, then the protocol rejects the attachment. For example, OSPF rejects attachment of a policy that tests the values of BGP communities. The situation is made more complex by the fact that each protocol has access to at least two distinct route types. In addition to native protocol routes, for example BGP or IS-IS, some protocol policy attach points operate on RIB routes, which is the common central representation. Using BGP as an example, the protocol provides an attach point to apply policy to routes redistributed from the RIB to BGP. An attach point dealing with two different kinds of routes permits a mix of operations: RIB attribute operations for matching and BGP attribute operations for setting. Cisco IOS XR Routing Configuration Guide RC-223 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy Note The protocol configuration rejects attempts to attach policies that perform unsupported operations. The following sections describe the protocol attach points, including information on the attributes (commands) and operations that are valid for each attach point. • BGP Policy Attach Points, page RC-224 • OSPF Policy Attach Points, page RC-231 • OSPFv3 Policy Attach Points, page RC-232 • IS-IS Policy Attach Points, page RC-234 See the Cisco IOS XR Routing Command Reference for more information on the attributes and operations. BGP Policy Attach Points This section describes each of the BGP policy attach points and provides a summary of the BGP attributes and operators. Aggregation The aggregation attach point generates an aggregate route to be advertised based on the conditional presence of subcomponents of that aggregate. Policies attached at this attach point are also able to set any of the valid BGP attributes on the aggregated routes. For example, the policy could set a community value or a MED on the aggregate that is generated. The specified aggregate is generated if any routes evaluated by the named policy pass the policy. More specifics of the aggregate are filtered using the suppress-route keyword. Any actions taken to set attributes in the route affect attributes on the aggregate. In the policy language, the configuration is controlled by which routes pass the policy. The suppress map was used to selectively filter or suppress specific components of the aggregate when the summary-only flag is not set. In other words, when the aggregate and more specific components are being sent, some of the more specific components can be filtered using a suppress map. In the policy language, this is controlled by selecting the route and setting the suppress flag. The attribute-map allowed the user to set specific attributes on the aggregated route. In the policy language, setting attributes on the aggregated route is controlled by normal action operations. In the following example, the aggregate address 10.0.0.0/8 is generated if there are any component routes in the range 10.0.0.0/8 ge 8 le 25 except for 10.2.0.0/24. Because summary-only is not set, all components of the aggregate are advertised. However, the specific component 10.1.0.0 are suppressed. route-policy sample if destination in (10.0.0.0/8 ge 8 le 25) then set community (10:33) endif if destination in (10.2.0.0/24) then drop endif if destination in (10.1.0.0/24) then suppress-route endif end-policy Cisco IOS XR Routing Configuration Guide RC-224 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy router bgp 2 address-family ipv4 aggregate-address 10.0.0.0/8 policy sample . . . Dampening The dampening attach point controls the default route-dampening behavior within BGP. Unless overridden by a more specific policy on the associate peer, all routes in BGP apply the associated policy to set their dampening attributes. The following policy sets dampening values for BGP IPv4 unicast routes. Those routes that are more specific than a /25 take longer to recover after they have been dampened than routes that are less specific than /25. route-policy sample_damp if destination in (0.0.0.0/0 ge 25) then set dampening halflife 30 others default else set dampening halflife 20 others default endif end-policy router bgp 2 address-family ipv4 unicast bgp dampening policy sample_damp . . . Default Originate The default originate attach point allows the default route (0.0.0.0/0) to be conditionally generated and advertised to a peer, based on the presence of other routes. It accomplishes this configuration by evaluating the associated policy against routes in the Routing Information Base (RIB). If any routes pass the policy, the default route is generated and sent to the relevant peer. The following policy generates and sends a default-route to the BGP neighbor 10.0.0.1 if any routes that match 10.0.0.0/8 ge 8 le 32 are present in the RIB. route-policy sample-originate if rib-has-route in (10.0.0.0/8 ge 8 le 32) then pass endif end-policy router bgp 2 neighbor 10.0.0.1 remote-as 3 address-family ipv4 unicast default-originate policy sample-originate . . . Note The current implementation of default origination policy permits matching only on destination address. Cisco IOS XR Routing Configuration Guide RC-225 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy Neighbor Export The neighbor export attach point selects the BGP routes to send to a given peer or group of peers. The routes are selected by running the set of possible BGP routes through the associated policy. Any routes that pass the policy are then sent as updates to the peer or group of peers. The routes that are sent may have had their BGP attributes altered by the policy that has been applied. The following policy sends all BGP routes to neighbor 10.0.0.5. Routes that are tagged with any community in the range 2:100 to 2:200 are sent with a MED of 100 and a community of 2:666. The rest of the routes are sent with a MED of 200 and a community of 2:200. route-policy sample-export if community matches-any (2:[100-200]) then set med 100 set community (2:666) else set med 200 set community (2:200) endif end-policy router bgp 2 neighbor 10.0.0.5 remote-as 3 address-family ipv4 unicast route-policy sample-export out . . . Neighbor Import The neighbor import attach point controls the reception of routes from a specific peer. All routes that are received by a peer are run through the attached policy. Any routes that pass the attached policy are passed to the BGP Routing Information Base (BRIB) as possible candidates for selection as best path routes. When a BGP import policy is modified, it is necessary to rerun all the routes that have been received from that peer against the new policy. The modified policy may now discard routes that were previously allowed through, allow through previously discarded routes, or change the way the routes are modified. A new configuration option in BGP (bgp auto-policy-soft-reset) that allows this modification to happen automatically in cases for which either soft reconfiguration is configured or the BGP route-refresh capability has been negotiated. The following example shows how to receive routes from neighbor 10.0.0.1. Any routes received with the community 3:100 have their local preference set to 100 and their community tag set to 2:666. All other routes received from this peer have their local preference set to 200 and their community tag set to 2:200. route-policy sample_import if community matches-any (3:100) then set local-preference 100 set community (2:666) else set local-preference 200 set community (2:200) endif end-policy Cisco IOS XR Routing Configuration Guide RC-226 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy router bgp 2 neighbor 10.0.0.1 remote-as 3 address-family ipv4 unicast route-policy sample_import in . . . Network The network attach point controls the injection of routes from the RIB into BGP. A route policy attached at this point is able to set any of the valid BGP attributes on the routes that are being injected. The following example shows a route policy attached at the network attach point that sets the well-known community no-export for any routes more specific than /24: route-policy NetworkControl if destination in (0.0.0.0/0 ge 25) then set community (no-export) additive endif end-policy router bgp 2 address-family ipv4 unicast network 172.16.0.5/27 route-policy NetworkControl Redistribute The redistribute attach point allows routes from other sources to be advertised by BGP. The policy attached at this point is able to set any of the valid BGP attributes on the routes that are being redistributed. Likewise, selection operators allow a user to control what route sources are being redistributed and which routes from those sources. The following example shows how to redistribute all routes from OSPF instance 12 into BGP. If OSPF were carrying a default route, it is dropped. Routes carrying a tag of 10 have their local preference set to 300 and the community value of 2:666 and no-advertise attached. All other routes have their local preference set to 200 and a community value of 2:100 set. route-policy sample_redistribute if destination in (0.0.0.0/0) then drop endif if tag eq 10 then set local-preference 300 set community (2:666, no-advertise) else set local-preference 200 set community (2:100) endif end-policy router bgp 2 address-family ipv4 unicast redistribute ospf 12 route-policy sample_redistribute . . Cisco IOS XR Routing Configuration Guide RC-227 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy Show bgp The show bgp attach point allows the user to display selected BGP routes that pass the given policy. Any routes that are not dropped by the attached policy are displayed in a manner similar to the output of the show ip bgp command. In the following example, the show bgp route-policy command is used to display any BGP routes carrying a MED of 5: route-policy sample-display if med eq 5 then pass endif end-policy ! show bgp route-policy sample-display A show bgp policy route-policy command also exists, which runs all routes in the RIB past the named policy as if the RIB were an outbound BGP policy. This command then displays what each route looked like before it was modified and after it was modified, as shown in the following example: RP/0/RP0/CPU0:router# show rpl route-policy test2 route-policy test2 if (destination in (10.0.0.0/8 ge 8 le 32)) then set med 333 endif end-policy ! RP/0/RP0/CPU0:router# show bgp BGP router identifier 10.0.0.1, local AS number 2 BGP main routing table version 11 BGP scan interval 60 secs Status codes:s suppressed, d damped, h history, * valid, > best i - internal, S stale Origin codes:i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *> 10.0.0.0 10.0.1.2 10 0 3 ? *> 10.0.0.0/9 10.0.1.2 10 0 3 ? *> 10.0.0.0/10 10.0.1.2 10 0 3 ? *> 10.0.0.0/11 10.0.1.2 10 0 3 ? *> 10.1.0.0/16 10.0.1.2 10 0 3 ? *> 10.3.30.0/24 10.0.1.2 10 0 3 ? *> 10.3.30.128/25 10.0.1.2 10 0 3 ? *> 10.128.0.0/9 10.0.1.2 10 0 3 ? *> 10.255.0.0/24 10.0.101.2 1000 555 0 100 e *> 10.255.64.0/24 10.0.101.2 1000 555 0 100 e .... Cisco IOS XR Routing Configuration Guide RC-228 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy RP/0/RP0/CPU0:router# show bgp policy route-policy test2 10.0.0.0/8 is advertised to 10.0.101.2 Path info: neighbor:10.0.1.2 neighbor router id:10.0.1.2 valid external best Attributes after inbound policy was applied: next hop:10.0.1.2 MET ORG AS origin:incomplete neighbor as:3 metric:10 aspath:3 Attributes after outbound policy was applied: next hop:10.0.1.2 MET ORG AS origin:incomplete neighbor as:3 metric:333 aspath:2 3 ... Table Policy The table policy attach point allows the user to configure traffic-index values on routes as they are installed into the global routing table. This attach point supports the BGP policy accounting feature. BGP policy accounting uses the traffic indexes that are set on the BGP routes to track various counters. This way, router operators can select different sets of BGP route attributes using the matching operations and then set different traffic indexes for each different class of route they are interested in tracking. The following example shows how to set the traffic index to 10 in IPv4 unicast routes that originated from autonomous system 10. Likewise, any IPv4 unicast routes that originated from autonomous system 11 have their traffic index set to 11 when they are installed into the FIB. These traffic indexes are then used to count traffic being forwarded on these routes in line cards by enabling the BGP policy accounting counters on the interfaces of interest. route-policy sample-table if as-path originates-from ‘10’ then set traffic-index 10 elseif as-path originates-from ‘11’ then set traffic-index 11 endif end-policy router bgp 2 address-family ipv4 unicast table-policy sample-table . . . BGP Attributes and Operators Table 3 summarizes the BGP attributes and operators. Cisco IOS XR Routing Configuration Guide RC-229 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy Table 3 BGP Attributes and Operators Attribute Match Set as-path in prepend is-local length neighbor-is originates-from passes-though unique-length community is-empty delete matches-any set matches-every dampening n/a set dampening... to set values that control the dampening (see Dampening, page RC-225) destination in n/a extended community is-empty delete matches-any set matches-every local-preference n/a set med is, eq, ge, le set set + set - next-hop in set origin is set rib-has-route in n/a route-type is n/a source in n/a suppress-route n/a suppress-route tag is, eq, ge, le set traffic-index n/a set unsuppress-route n/a unsuppress-route weight n/a set Some BGP route attributes are inaccessible from some BGP attach points for various reasons. For example, the set med igp-cost only command makes sense when there is a configured igp-cost to provide a source value. Table 4 summarizes which operations are valid and where they are valid. Cisco IOS XR Routing Configuration Guide RC-230 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy Table 4 Restricted BGP Operations by Attach Point import export aggregation redistribution prepend as-path eBGP only eBGP only n/a n/a set med igp-cost forbidden eBGP only forbidden forbidden set weight n/a forbidden n/a n/a suppress forbidden forbidden n/a forbidden OSPF Policy Attach Points This section describes each of the OSPF policy attach points and provides a summary of the OSPF attributes and operators. Default Originate The default originate attach point allows the user to conditionally inject the default route 0.0.0.0/0 into the OSPF link-state database, which is done by evaluating the attached policy. If any routes in the local RIB pass the policy, then the default route is inserted into the link-state database. The following example shows how to generate a default route if any of the routes that match 10.0.0.0/8 ge 8 le 25 are present in the RIB: route-policy ospf-originate if rib-has-route in (10.0.0.0/8 ge 8 le 25) then pass endif end-policy router ospf 1 default-information originate policy ospf-originate . . . Redistribute The redistribute attach point within OSPF injects routes from other routing protocol sources into the OSPF link-state database, which is done by selecting the route types it wants to import from each protocol. It then sets the OSPF parameters of cost and metric type. The policy can control how the routes are injected into OSPF by using the set level command. The following example shows how to redistribute routes from IS-IS instance instance_10 into OSPF instance 1 using the policy OSPF-redist. The policy sets the metric type to type-2 for all redistributed routes. IS-IS routes with a tag of 10 have their cost set to 100, and IS-IS routes with a tag of 20 have their OSPF cost set to 200. Any IS-IS routes not carrying a tag of either 10 or 20 are not be redistributed into the OSPF link-state database. Cisco IOS XR Routing Configuration Guide RC-231 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy route-policy OSPF-redist set metric-type type-2 if tag eq 10 then set cost 100 elseif tag eq 20 then set cost 200 else drop endif end-policy router ospf 1 redistribute isis instance_10 policy OSPF-redist . . . OSPF Attributes and Operators Table 5 summarizes the OSPF attributes and operators. Table 5 OSPF Attributes and Operators Attribute Match Set cost n/a set destination in n/a metric-type n/a set rib-has-route in n/a route-type is n/a tag eq, ge, le set OSPFv3 Policy Attach Points This section describes each of the OSPFv3 policy attach points and provides a summary of the BGP attributes and operators. Default Originate The default originate attach point allows the user to conditionally inject the default route 0::/0 into the OSPFv3 link-state database, which is done by evaluating the attached policy. If any routes in the local RIB pass the policy, then the default route is inserted into the link-state database. The following example shows how to generate a default route if any of the routes that match 2001::/96 are present in the RIB: route-policy ospfv3-originate if rib-has-route in (2001::/96) then pass endif end-policy Cisco IOS XR Routing Configuration Guide RC-232 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy router ospfv3 1 default-information originate policy ospfv3-originate . . . Redistribute The redistribute attach point within OSPFv3 injects routes from other routing protocol sources into the OSPFv3 link-state database, which is done by selecting the route types it wants to import from each protocol. It then sets the OSPFv3 parameters of cost and metric type. The policy can control how the routes are injected into OSPFv3 by using the metric type command. The following example shows how to redistribute routes from BGP instance instance_15 into OSPF instance 1 using the policy OSPFv3-redist. The policy sets the metric type to type-2 for all redistributed routes. BGP routes with a tag of 10 have their cost set to 100, and BGP routes with a tag of 20 have their OSPFv3 cost set to 200. Any BGP routes not carrying a tag of either 10 or 20 are not be redistributed into the OSPFv3 link-state database. route-policy OSPFv3-redist set metric-type type-2 if tag eq 10 then set cost 100 elseif tag eq 20 then set cost 200 else drop endif end-policy router ospfv3 1 redistribute bgp instance_15 policy OSPFv3-redist . . . OSPFv3 Attributes and Operators Table 6 summarizes the OSPFv3 attributes and operators. Table 6 OSPFv3 Attributes and Operators Attribute Match Set cost n/a set destination in n/a metric-type n/a set rib-has-route in n/a route-type is n/a tag eq, ge, le set Cisco IOS XR Routing Configuration Guide RC-233 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy IS-IS Policy Attach Points This section describes each of the IS-IS policy attach points and provides a summary of the BGP attributes and operators. Redistribute The redistribute attach point within IS-IS allows routes from other protocols to be readvertised by IS-IS. The policy is a set of control structures for selecting the types of routes that a user wants to redistribute into IS-IS. The policy can also control which IS-IS level the routes are injected into and at what metric values. The following example shows how to redistribute routes from IS-IS instance 1 into IS-IS instance instance_10 using the policy ISIS-redist. This policy sets the level to level-1-2 for all redistributed routes. OSPF routes with a tag of 10 have their metric set to 100, and IS-IS routes with a tag of 20 have their IS-IS metric set to 200. Any IS-IS routes not carrying a tag of either 10 or 20 are not be redistributed into the IS-IS database. route-policy ISIS-redist set level level-1-2 if tag eq 10 then set metric 100 elseif tag eq 20 then set metric 200 else drop endif end-policy router isis instance_10 address-family ipv4 unicast redistribute ospf 1 policy ISIS-redist . . . IS-IS Attributes and Operators Table 7 summarizes the IS-IS attributes and operators. Table 7 IS-IS Attributes and Operators Attribute Match Set Destination in n/a Level n/a set metric n/a set metric-type n/a set rib-has-route in n/a route-type is n/a tag eq, ge, le n/a Cisco IOS XR Routing Configuration Guide RC-234 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy Attached Policy Modification Policies that are in use do, on occasion, need to be modified. In the traditional configuration model, a policy modification would be done by completely removing the policy and re-entering it. However, this model allows for a window of time in which no policy is attached and default actions to be used, which is an opportunity for inconsistencies to exist. To close this window of opportunity, you can modify a policy in use at an attach point by respecifying it, which allows for policies that are in use to be changed, without having a window of time in which no policy is applied at the given attach point. Note A route policy or set that is in use at an attach point cannot be removed because this removal would result in an undefined reference. An attempt to remove a route policy or set that is in use at an attach point results in an error message to the user. Nonattached Policy Modification As long as a given policy is not attached at an attach point, the policy is allowed to refer to nonexistent sets and policies. Configurations can be built that reference sets or policy blocks that are not yet defined, and then later those undefined policies and sets can be filled in. This method of building configurations gives much greater flexibility in policy definition. Every piece of policy you want to reference while defining a policy need not exist in the configuration. Thus, you can define a policy sample1 that references a policy sample2 using an apply statement even if the policy sample2 does not exist. Similarly, you can enter a policy statement that refers to a nonexistent set. However, the existence of all referenced policies and sets is enforced when a policy is attached. Thus, if a user attempts to attach the policy sample1 with the reference to an undefined policy sample2 at an inbound BGP policy using the statement neighbor 1.2.3.4 address-family ipv4 unicast policy sample1 in, the configuration attempt is rejected because the policy sample2 does not exist. Editing Routing Policy Configuration Elements RPL is based on statements rather than on lines. That is, within the begin-end pair that brackets policy statements from the CLI, a new line is merely a separator, the same as a space character. The CLI provides the means to enter and delete route policy statements. RPL provides a means to edit the contents of the policy between the begin-end brackets using a microemacs editor. Editing Routing Policy Configuration Elements Using the EMACS Editor To edit the contents of a routing policy, use the following CLI command in EXEC mode: edit {route-policy | prefix-set | as-path-set | community-set | extended-community-set} name A copy of the route policy is copied to a temporary file and the editor is launched. After editing, save the changes by using the save-buffer command, C-X C-S (Control-X Control-S). To exit the editor, use the quit command, Control-X Control-C. When you quit the editor, the buffer is committed. If there are no parse errors, the configuration is committed: Cisco IOS XR Routing Configuration Guide RC-235 Implementing Routing Policy on Cisco IOS XR Software Information About Implementing Routing Policy RP/0/RP0/CPU0:router# edit route-policy policy_A ---------------------------------------== MicroEMACS 3.8b () == rpl_edit.139281 == if destination in (2001::/8) then drop endif end-policy ! == MicroEMACS 3.8b () == rpl_edit.139281 == Parsing. 83 bytes parsed in 1 sec (82)bytes/sec Committing. 1 items committed in 1 sec (0)items/sec Updating. Updated Commit database in 1 sec RP/0/RP0/CPU0:router# If there are parse errors, you are asked whether editing should continue: RP/0/RP0/CPU0:router#edit route-policy policy_B == MicroEMACS 3.8b () == rpl_edit.141738 route-policy policy_B set metric-type type_1 if destination in (2001::/8) then drop endif end-policy ! == MicroEMACS 3.8b () == rpl_edit.141738 == Parsing. 105 bytes parsed in 1 sec (103)bytes/sec % Syntax/Authorization errors in one or more commands.!! CONFIGURATION FAILED DUE TO SYNTAX/AUTHORIZATION ERRORS set metric-type type_1 if destination in (2001::/8) then drop endif end-policy ! Continue editing? [no]: If you answer yes, the editor continues on the text buffer from where you left off. If you answer no, the running configuration is not changed and the editing session is ended. Editing Routing Policy Configuration Elements Using the CLI The CLI allows you to enter and delete route policy statements. You can complete a policy configuration block by entering applicable commands such as end-policy or end-set. Alternatively, the CLI interpreter allows you to use the exit command to complete a policy configuration block. The abort command is used to discard the current policy configuration and return to global configuration mode. Cisco IOS XR Routing Configuration Guide RC-236 Implementing Routing Policy on Cisco IOS XR Software How to Implement Routing Policy How to Implement Routing Policy This section contains the following procedures: • Defining a Route Policy, page RC-237 (required) • Attaching a Routing Policy to a BGP Neighbor, page RC-238 (required) • Modifying a Routing Policy Using the Microemacs Editor, page RC-240 (optional) Defining a Route Policy This task explains how to define a route policy. Note If you want to modify an existing routing policy using the command-line interface (CLI), you must redefine the policy by completing this task. SUMMARY STEPS 1. configure 2. route-policy name 3. end-policy 4. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 route-policy name Enters route-policy configuration mode. • Example: After the route-policy has been entered, a group of commands can be entered to define the route-policy. RP/0/RP0/CPU0:router(config)# route-policy sample1 Cisco IOS XR Routing Configuration Guide RC-237 Implementing Routing Policy on Cisco IOS XR Software How to Implement Routing Policy Step 3 Command or Action Purpose end-policy Ends the definition of a route policy and exits route-policy configuration mode. Example: RP/0/RP0/CPU0:router(config-rpl)# end-policy Step 4 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Attaching a Routing Policy to a BGP Neighbor This task explains how to attach a routing policy to a BGP neighbor. The procedure to attach a routing policy to an IS-IS or OSPF neighbor is the same as BGP, except that the commands and applicable arguments vary. Prerequisites A routing policy must be preconfigured and well defined prior to it being applied at an attach point. If a policy is not predefined, an error message is generated stating that the policy is not defined. SUMMARY STEPS 1. configure 2. router bgp as-number 3. neighbor ip-address 4. address-family {ipv4 | ipv6} {multicast | unicast} 5. route-policy route-policy-name {in | out} 6. end or commit Cisco IOS XR Routing Configuration Guide RC-238 Implementing Routing Policy on Cisco IOS XR Software How to Implement Routing Policy DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 router bgp as-number Example: Configures a BGP routing process and enters router configuration mode. • RP/0/RP0/CPU0:router(config)# router bgp 125 Step 3 neighbor ip-address The as-number argument identifies the autonomous system in which the router resides. Valid values are from 0 to 65535. Private autonomous system numbers that can be used in internal networks range from 64512 to 65535. Specifies a neighbor IP address. Example: RP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.0.20 Step 4 address-family {ipv4 | ipv6} {multicast | unicast} Example: Specifies the address family, the version of IP that is in use, and either multicast or unicast. • Enters address family configuration mode. RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicast Cisco IOS XR Routing Configuration Guide RC-239 Implementing Routing Policy on Cisco IOS XR Software How to Implement Routing Policy Step 5 Command or Action Purpose route-policy policy-name {in | out} Attaches the route-policy, which must be well formed and predefined. Example: RP/0/RP0/CPU0:router(config-bgp-nbr-af)# route-policy example1 in Step 6 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config-bgp-nbr-af)# end or – Entering yes saves configuration changes to RP/0/RP0/CPU0:router(config-bgp-nbr-af)# commit the running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Modifying a Routing Policy Using the Microemacs Editor This task explains how to modify an existing routing policy using the microemacs editor. SUMMARY STEPS 1. edit {route-policy | prefix-set | as-path-set | community-set | extended-community-set} name 2. show rpl route-policy name [detail] 3. show rpl prefix-set name Cisco IOS XR Routing Configuration Guide RC-240 Implementing Routing Policy on Cisco IOS XR Software Configuration Examples for Implementing Routing Policy DETAILED STEPS Step 1 Command or Action Purpose edit {route-policy | prefix-set | as-path-set | community-set | extended-community-set} name Identifies the route policy, prefix set, AS path set, community set, or extended community set name to be modified. Example: • RP/0/RP0/CPU0:router# edit route-policy sample1 A copy of the route policy, prefix set, AS path set, community set, or extended community set is copied to a temporary file and the microemacs editor is launched. When you finish editing the policy or set, save the changes by using the save-buffer command, ^X^S (Control-X Control-S). To commit the changed configuration: Step 2 show rpl route-policy name [detail] • save the buffer (Control-X Control-S) • exit MicroEmacs (Control-X Control-C) (Optional) Displays the configuration of a specific named route policy. • Example: RP/0/RP0/CPU0:router# show rpl route-policy sample2 Step 3 show rpl prefix-set name (Optional) Displays the contents of a named prefix set. • Example: RP/0/RP0/CPU0:router# show rpl prefix-set prefixset1 Use the detail keyword to display all policies and sets that a policy uses. To display the contents of a named AS path set, community set, or extended community set, replace the prefix-set keyword with as-path-set, community-set, or extcommunity-set, respectively. Configuration Examples for Implementing Routing Policy This section provides the following configuration examples: • Routing Policy Definition: Example, page RC-241 • Simple Inbound Policy: Example, page RC-242 • Modular Inbound Policy: Example, page RC-243 • Translating Cisco IOS Route Maps to Cisco IOS XR Routing Policy Language: Example, page RC-244 Routing Policy Definition: Example In the following example, a BGP route policy named sample1 is defined using the route-policy name command. The policy compares the network layer reachability information (NLRI) to the elements in the prefix set test. If it evaluates to true, the policy performs the operations in the then clause. If it evaluates to false, the policy performs the operations in the else clause, that is, sets the MED value to 200 and adds the community 2:100 to the route. The final steps of the example commit the configuration to the router, exit configuration mode, and display the contents of route policy sample1. Cisco IOS XR Routing Configuration Guide RC-241 Implementing Routing Policy on Cisco IOS XR Software Configuration Examples for Implementing Routing Policy configure route-policy sample1 if destination in test then drop else set med 200 set community (2:100) additive endif end-policy end show config running route-policy sample1 Building configuration... route-policy sample1 if destination in test then drop else set med 200 set community (2:100) additive endif end-policy Simple Inbound Policy: Example The following policy discards any route whose network layer reachability information (NLRI) specifies a prefix longer than /24, and any route whose NLRI specifies a destination in the address space reserved by RFC 1918. For all remaining routes, it sets the MED and local preference, and adds a community to the list in the route. For routes whose community lists include any values in the range from 101:202 to 106:202 that have a 16-bit tag portion containing the value 202, the policy prepends autonomous system number 2 twice, and adds the community 2:666 to the list in the route. Of these routes, if the MED is either 666 or 225, then the policy sets the origin of the route to incomplete, and otherwise sets the origin to IGP. For routes whose community lists do not include any of the values in the range from 101:202 to 106:202, the policy adds the community 2:999 to the list in the route. prefix-set too-specific 0.0.0.0/0 ge 25 le 32 end-set prefix-set rfc1918 10.0.0.0/8 le 32, 172.16.0.0/12 le 32, 192.168.0.0/16 le 32 end-set route-policy inbound-tx if destination in too-specific or destination in rfc1918 then drop endif set med 1000 set local-preference 90 set community (2:1001) additive if community matches-any ([101..106]:202) then prepend as-path 2 2 set community (2:666) additive if med is 666 or med is 225 then set origin incomplete else set origin igp Cisco IOS XR Routing Configuration Guide RC-242 Implementing Routing Policy on Cisco IOS XR Software Configuration Examples for Implementing Routing Policy endif else set community (2:999) additive endif end-policy router bgp 2 neighbor 10.0.1.2 address-family ipv4 unicast route-policy inbound-tx in Modular Inbound Policy: Example The following policy example shows how to build two inbound policies, in-100 and in-101, for two different peers. In building the specific policies for those peers, the policy reuses some common blocks of policy that may be common to multiple peers. It builds a few basic building blocks, the policies common-inbound, filter-bogons, and set-lpref-prepend. The filter-bogons building block is a simple policy that filters all undesirable routes, such as those from the RFC 1918 address space. The policy set-lpref-prepend is a utility policy that can set the local preference and prepend the AS path according to parameterized values that are passed in. The common-inbound policy uses these filter-bogons building blocks to build a common block of inbound policy. The common-inbound policy is used as a building block in the construction of in-100 and in-101 along with the set-lpref-prepend building block. This is a simple example that illustrates the modular capabilities of the policy language. prefix-set bogon 10.0.0.0/8 ge 8 le 32, 0.0.0.0, 0.0.0.0/0 ge 27 le 32, 192.168.0.0/16 ge 16 le 32 end-set ! route-policy in-100 apply common-inbound if community matches-any ([100..120]:135) then apply set-lpref-prepend (100,100,2) set community (2:1234) additive else set local-preference 110 endif if community matches-any ([100..666]:[100..999]) then set med 444 set local-preference 200 set community (no-export) additive endif end-policy ! route-policy in-101 apply common-inbound if community matches-any ([101..200]:201) then apply set-lpref-prepend(100,101,2) set community (2:1234) additive else set local-preference 125 endif end-policy ! route-policy filter-bogons if destination in bogon then drop else Cisco IOS XR Routing Configuration Guide RC-243 Implementing Routing Policy on Cisco IOS XR Software Additional References pass endif end-policy ! route-policy common-inbound apply filter-bogons set origin igp set community (2:333) end-policy ! route-policy set-lpref-prepend($lpref,$as,$prependcnt) set local-preference $lpref prepend as-path $as $prependcnt end-policy Translating Cisco IOS Route Maps to Cisco IOS XR Routing Policy Language: Example RPL performs the same functions as route-maps. See the Converting Cisco IOS Configurations to Cisco IOS XR Configurations guide. Additional References The following sections provide references related to implementing RPL. Related Documents Related Topic Document Title Routing policy language commands: complete Routing Policy Language Commands on Cisco IOS XR Software, command syntax, command modes, command history, Release 3.2 defaults, usage guidelines, and examples Regular expression syntax “Understanding Regular Expressions, Special Characters and Patterns” appendix in the Cisco IOS XR Getting Started Guide Standards Standards Title Draft-ietf-idr-bgp4-26.txt A Border Gateway Protocol 4, by Y. Rekhter, T.Li, S. Hares Cisco IOS XR Routing Configuration Guide RC-244 Implementing Routing Policy on Cisco IOS XR Software Additional References MIBs MIBs MIBs Link There are no applicable MIBs for this module. To locate and download MIBs for selected platforms using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL: http://cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml RFCs RFCs Title No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. — Technical Assistance Description Link http://www.cisco.com/techsupport The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content. Cisco IOS XR Routing Configuration Guide RC-245 Implementing Routing Policy on Cisco IOS XR Software Additional References Cisco IOS XR Routing Configuration Guide RC-246 Implementing Static Routes on Cisco IOS XR Software Static routes are user-defined routes that cause packets moving between a source and a destination to take a specified path. Static routes can be important if the Cisco IOS XR software cannot build a route to a particular destination. They are useful for specifying a gateway of last resort to which all unroutable packets are sent. This module describes the tasks you need to implement static routes on your Cisco IOS XR network. Note For more information about static routes on the Cisco IOS XR software and complete descriptions of the static routes commands listed in this module, see the “Related Documents” section of this module. To locate documentation for other commands that might appear while executing a configuration task, search online in the Cisco IOS XR software master command index. Feature History for Implementing Static Routes on Cisco IOS XR Software Release Modification Release 2.0 This feature was introduced on the Cisco CRS-1. Release 3.0 No modification. Release 3.2 Support was added for the Cisco XR 12000 Series Router. Contents • Prerequisites for Implementing Static Routes on Cisco IOS XR Software, page RC-248 • Information About Implementing Static Routes on Cisco IOS XR Software, page RC-248 • How to Implement Static Routes on Cisco IOS XR Software, page RC-250 • Configuration Examples, page RC-255 • Where to Go Next, page RC-255 • Additional References, page RC-256 Cisco IOS XR Routing Configuration Guide RC-247 Implementing Static Routes on Cisco IOS XR Software Prerequisites for Implementing Static Routes on Cisco IOS XR Software Prerequisites for Implementing Static Routes on Cisco IOS XR Software To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide. Information About Implementing Static Routes on Cisco IOS XR Software To implement static routes you need to understand the following concepts: • Static Route Functional Overview, page RC-248 • Default Administrative Distance, page RC-248 • Directly Connected Routes, page RC-249 Static Route Functional Overview Static routes are entirely user configurable and can point to a next-hop interface, next-hop IP address, or both. In Cisco IOS XR software, if an interface was specified, then the static route is installed in the Routing Information Base (RIB) if the interface is reachable. If an interface was not specified, the route is installed if the next-hop address is reachable. The only exception to this configuration is when a static route is configured with the permanent attribute, in which case it is installed in RIB regardless of reachability. Networking devices forward packets using route information that is either manually configured or dynamically learned using a routing protocol. Static routes are manually configured and define an explicit path between two networking devices. Unlike a dynamic routing protocol, static routes are not automatically updated and must be manually reconfigured if the network topology changes. The benefits of using static routes include security and resource efficiency. Static routes use less bandwidth than dynamic routing protocols, and no CPU cycles are used to calculate and communicate routes. The main disadvantage to using static routes is the lack of automatic reconfiguration if the network topology changes. Static routes can be redistributed into dynamic routing protocols, but routes generated by dynamic routing protocols cannot be redistributed into the static routing table. No algorithm exists to prevent the configuration of routing loops that use static routes. Static routes are useful for smaller networks with only one path to an outside network and to provide security for a larger network for certain types of traffic or links to other networks that need more control. In general, most networks use dynamic routing protocols to communicate between networking devices but may have one or two static routes configured for special cases. Default Administrative Distance Static routes have a default administrative distance of 1. A low number indicates a preferred route. By default, static routes are preferred to routes learned by routing protocols. Therefore, you can configure an administrative distance with a static route if you want the static route to be overridden by dynamic Cisco IOS XR Routing Configuration Guide RC-248 Implementing Static Routes on Cisco IOS XR Software Information About Implementing Static Routes on Cisco IOS XR Software routes. For example, you could have routes installed by the Open Shortest Path First (OSPF) protocol with an administrative distance of 120. To have a static route that would be overridden by an OSPF dynamic route, specify an administrative distance greater than 120. Directly Connected Routes The routing table considers the static routes that point to an interface as “directly connected.” Directly connected networks are advertised by IGP routing protocols if a corresponding interface command is contained under the router configuration stanza of that protocol. In directly attached static routes, only the output interface is specified. The destination is assumed to be directly attached to this interface, so the packet destination is used as the next hop address. The following example shows how to specify that all destinations with address prefix 2001:0DB8::/32 are directly reachable through interface GigabitEthernet 0/5/0/0: RP/0/RP0/CPU0:router(config)# route ipv6 unicast 2001:0DB8::/32 gigabitethernet 0/5/0/0 Directly attached static routes are candidates for insertion in the routing table only if they refer to a valid interface; that is, an interface that is both up and has IPv4 or IPv6 enabled on it. Recursive Static Routes In a recursive static route, only the next hop is specified. The output interface is derived from the next hop. The following example shows how to specify that all destinations with address prefix 2001:0DB8::/32 are reachable through the host with address 2001:0DB8:3000::1: RP/0/RP0/CPU0:router(config)# route ipv6 unicast 2001:0DB8::/32 2001:0DB8:3000::1 A recursive static route is valid (that is, it is a candidate for insertion in the routing table) only when the specified next hop resolves, either directly or indirectly, to a valid output interface, provided the route does not self-recurse, and the recursion depth does not exceed the maximum IPv6 forwarding recursion depth. A route self-recurses if it is itself used to resolve its own next hop. If a static route becomes self-recursive, RIB sends a notification to static routes to withdraw the recursive route. The following example shows how to define a recursive IPv6 static route: RP/0/RP0/CPU0:router(config)# route ipv6 unicast 2001:0DB8::/32 2001:0DB8:3000::1 This static route is not inserted into the IPv6 routing table because it is self-recursive. The next hop of the static route, 2001:0DB8:3000:1, resolves through the BGP route 2001:0DB8:3000:0/16, which is itself a recursive route (that is, it only specifies a next hop). The next hop of the BGP route, 2001:0DB8::0104, resolves through the static route. Therefore, the static route would be used to resolve its own next hop. It is not normally useful to manually configure a self-recursive static route, although it is not prohibited. However, a recursive static route that has been inserted in the routing table may become self-recursive as a result of some transient change in the network learned through a dynamic routing protocol. If this occurs, the fact that the static route has become self-recursive will be detected and it will be removed from the routing table, although not from the configuration. A subsequent network change may cause the static route to no longer be self-recursive, in which case it will be re-inserted in the routing table. Cisco IOS XR Routing Configuration Guide RC-249 Implementing Static Routes on Cisco IOS XR Software How to Implement Static Routes on Cisco IOS XR Software Fully Specified Static Routes In a fully specified static route, both the output interface and next hop are specified. This form of static route is used when the output interface is a multiaccess one and it is necessary to explicitly identify the next hop. The next hop must be directly attached to the specified output interface. The following example shows a definition of a fully specified static route: RP/0/RP0/CPU0:router(config)# route ipv6 unicast 2001:0DB8::/32 2001:0DB8:3000::1 A fully specified route is valid (that is, a candidate for insertion into the routing table) when the specified interface is IPv4 or IPv6 enabled and up. Floating Static Routes Floating static routes are static routes that are used to back up dynamic routes learned through configured routing protocols. A floating static route is configured with a higher administrative distance than the dynamic routing protocol it is backing up. As a result, the dynamic route learned through the routing protocol is always preferred to the floating static route. If the dynamic route learned through the routing protocol is lost, the floating static route is used in its place. The following example shows how to define a floating static route: RP/0/RP0/CPU0:router(config)# route ipv6 unicast 2001:0DB8::/32 2001:0DB8:3000::1 210 Any of the three types of static routes can be used as a floating static route. A floating static route must be configured with an administrative distance that is greater than the administrative distance of the dynamic routing protocol because routes with smaller administrative distances are preferred. Note By default, static routes have smaller administrative distances than dynamic routes, so static routes preferred to dynamic routes. How to Implement Static Routes on Cisco IOS XR Software This section contains the following procedures: • Configuring a Static Route, page RC-250 (required) • Configuring a Floating Static Route, page RC-251 (optional) • Changing the Maximum Number of Allowable Static Routes, page RC-253 (optional) Configuring a Static Route This task explains how to configure a static route. SUMMARY STEPS 1. configure 2. route {ipv4 | ipv6} {unicast | multicast} prefix mask {ip-address | interface-type interface-instance} [distance] [tag tag] [permanent] Cisco IOS XR Routing Configuration Guide RC-250 Implementing Static Routes on Cisco IOS XR Software How to Implement Static Routes on Cisco IOS XR Software 3. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 route {ipv4 | ipv6} {unicast | multicast} prefix mask {ip-address | interface-type interface-instance} [distance] [tag tag] [permanent] Configures an administrative distance of 110. • Example: This example shows how to route packets for network 10.0.0.0 through to a router at 172.20.16.6 if dynamic information with administrative distance less than 110 is not available. RP/0/RP0/CPU0:router(config)# route ipv4 unicast 10.0.0.0/8 172.20.16.6 110 Step 3 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Configuring a Floating Static Route This task explains how to configure a floating static route. SUMMARY STEPS 1. configure 2. route {ipv4 | ipv6} {unicast | multicast} prefix mask {ip-address | interface-type interface-instance} [distance] [tag tag] [permanent] Cisco IOS XR Routing Configuration Guide RC-251 Implementing Static Routes on Cisco IOS XR Software How to Implement Static Routes on Cisco IOS XR Software 3. end or commit DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 route {ipv4 | ipv6} {unicast | multicast} prefix mask {ip-address | interface-type interface-instance} [distance] [tag tag] [permanent] Example: In this example, a floating static IPv6 route is being configured. An administrative distance of 201 is configured Default administrative distances are as follows: • Connected interface—0 • Static route—1 RP/0/RP0/CPU0:router(config)# route ipv6 unicast 2001:0DB8::/32 2001:0DB8:3000::1 201 Step 3 Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Cisco IOS XR Routing Configuration Guide RC-252 Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Implementing Static Routes on Cisco IOS XR Software How to Implement Static Routes on Cisco IOS XR Software Changing the Maximum Number of Allowable Static Routes This task explains how to change the maximum number of allowable static routes. Restrictions The number of static routes that can be configured on a router for a given address family is limited by default to 4000. The limit can be raised or lowered using the route maximum command. Note that if you use the route maximum command to reduce the configured maximum allowed number of static routes for a given address family below the number of static routes currently configured, the change is rejected. In addition, understand the following behavior: If you commit a batch of routes that would, when grouped, push the number of static routes configured above the maximum allowed, the first n routes in the batch are accepted. The number previously configured is accepted, and the remainder are rejected. The n argument is the difference between the maximum number allowed and number previously configured. SUMMARY STEPS 1. configure 2. route maximum {ipv4 | ipv6} value 3. end or commit Cisco IOS XR Routing Configuration Guide RC-253 Implementing Static Routes on Cisco IOS XR Software How to Implement Static Routes on Cisco IOS XR Software DETAILED STEPS Step 1 Command or Action Purpose configure Enters global configuration mode. Example: RP/0/RP0/CPU0:router# configure Step 2 route maximum {ipv4 | ipv6} value Example: RP/0/RP0/CPU0:router(config)# route maximum ipv4 10000 Step 3 Changes the maximum number of allowable static routes. • Specify IPv4 or IPv6 address prefixes. • Specify the maximum number of static routes for the given address family. The range is from 1 to 128000. • This example sets the maximum number of static IPv4 routes to 10000. Saves configuration changes. end or commit When you issue the end command, the system prompts you to commit changes: Example: Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]: • RP/0/RP0/CPU0:router(config)# end or – Entering yes saves configuration changes to the RP/0/RP0/CPU0:router(config)# commit running configuration file, exits the configuration session, and returns the router to EXEC mode. – Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes. – Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes. • Cisco IOS XR Routing Configuration Guide RC-254 Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session. Implementing Static Routes on Cisco IOS XR Software Configuration Examples Configuration Examples This section provides the following configuration examples: • Configuring Traffic Discard: Example • Configuring a Fixed Default Route: Example • Configuring a Floating Static Route: Example Configuring Traffic Discard: Example Configuring a static route to point at interface null 0 may be used for discarding traffic to a particular prefix. For example, if it is required to discard all traffic to prefix 2001:0DB8:42:1/64, the following static route would be defined: configure route ipv6 unicast 2001:0DB8:42:1::/64 null 0 end Configuring a Fixed Default Route: Example A default static route is often used in simple router topologies. In the following example, a router is configured with an administrative distance of 110. configure route ipv4 unicast 10.0.0.0/8 172.20.16.6 110 end Configuring a Floating Static Route: Example A floating static route often is used to provide a backup path if connectivity fails. In the following example, a router is configured with an administrative distance of 201. configure route ipv6 unicast 2001:0DB8::/32 2001:0DB8:3000::1 201 end Where to Go Next For additional information on static routes, routing protocols, and RIB, consult the following publications: • Implementing and Monitoring RIB on Cisco IOS XR Software • Implementing BGP on Cisco IOS XR Software • Implementing IS-IS on Cisco IOS XR Software • Implementing OSPF on Cisco IOS XR Software • Implementing OSPFv3 on Cisco IOS XR Software • RIB Commands on Cisco IOS XR Software Cisco IOS XR Routing Configuration Guide RC-255 Implementing Static Routes on Cisco IOS XR Software Additional References Additional References The following sections provide references related to implementing static routes on Cisco IOS XR software. Related Documents Related Topic Document Title Static routes commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples Static and Utility Routing Commands on Cisco IOS XR Software, Release 3.2 Standards Standards Title No new or modified standards are supported by this — feature, and support for existing standards has not been modified by this feature. MIBs MIBs MIBs Link There are no applicable MIBs for this module. To locate and download MIBs for selected platforms using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL: http://cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml RFCs RFCs Title No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. — Technical Assistance Description Link http://www.cisco.com/techsupport The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content. Cisco IOS XR Routing Configuration Guide RC-256 I N D EX BGP (Border Gateway Protocol) HC Cisco IOS XR Interface and Hardware Component Configuration Guide IC Cisco IOS XR IP Addresses and Services Configuration Guide MCC Cisco IOS XR Multicast Configuration Guide MPC Cisco IOS XR MPLS Configuration Guide QC Cisco IOS XR Modular Quality of Service Configuration Guide description RC Cisco IOS XR Routing Configuration Guide functional overview SC Cisco IOS XR System Security Configuration Guide inheritance, monitoring SMC Cisco IOS XR System Management Configuration Guide local next-hop addresses, validating bestpath algorithm configuration grouping RC-5 inheriting RC-7 RC-1 multiprotocol A RC-18 RC-2 RC-11 RC-21 neighbors, maximum limits on address family command RC-5 RC-96 RC-197 advertisement-interval command aggregate-address command apply command RC-56 RC-44 RC-225 neighbor export RC-226 neighbor import RC-226 RC-227 redistribute RC-134 show bgp RC-146 RC-227 RC-228 table policy attached bit on an IS-IS instance RC-90 RC-229 policy attach points, aggregation authentication RC-224 router identifier MD5 (OSPFv2) RC-135 route, key rollover (OSPFv2) strategies RC-225 default originate network RC-223 Area Border Routers (ABRs) area command dampening RC-113 administrative distance RC-3 policy attach points address-family command (IS-IS) adjacencies, tuning RC-4 router identifier RC-136 routing policy RC-136 enforcing authentication, configuring (OSPFv2) authentication command (OSPFv2) RC-155 RC-132 B description RC-162 Autonomous System Boundary Routers (ASBRs) RC-16 update groups RC-156 authentication message-digest command autonomous systems RC-3 example RC-134 RC-18 RC-77 bgp bestpath as-path ignore command RC-40 bgp bestpath compare-routerid command bgp bestpath med always command RC-40 bgp bestpath med confed command RC-40 RC-41 bgp bestpath med missing-as-worst command backbone area RC-133 bestpath algorithm RC-18 bgp confederation identifier command bgp confederation peers command RC-40 RC-32 RC-33 Cisco IOS XR Routing Configuration Guide RC-257 Index bgp dampening command bgp redistribute-internal command RC-49 bgp default local-preference command bgp global address family submode aggregate-address command bgp dampening command distance bgp command network command bgp router submode RC-36 RC-5 bgp bestpath as-path ignore command RC-5 RC-40 bgp bestpath compare-routerid command RC-44 RC-49 RC-54 bgp bestpath med always command RC-40 bgp bestpath med confed command RC-40 bgp confederation identifier command RC-47 See address family command bgp confederation peers command table-policy command bgp default local-preference command RC-53 bgp neighbor address family submode next-hop self command bgp redistribute-internal command RC-5 default-metric command RC-65 route-policy (BGP) command route-policy command timers bgp command RC-31 See neighbor address family command RC-39 RC-6, RC-56 advertisement-interval command description command RC-56 RC-56 password accept command RC-57 password-disable command RC-57 receive-buffer-size command See neighbor-group command RC-57 RC-57 update-source command bgp neighbor submode RC-97 clear bgp flap-statistics command clear bgp soft in command RC-51 RC-71 clear bgp soft out command RC-72 RC-181 clear ospfv3 command RC-181 csnp-interval command RC-104 D dampening, route RC-23 RC-57 RC-5 RC-152 default address family RC-15 default-cost command RC-149 default-information originate command default-metric command shutdown command description command RC-70 RC-58 Cisco IOS XR Routing Configuration Guide RC-258 RC-50 clear bgp flap-statistics reexp command See bgp neighbor command use command RC-77 C dead interval command RC-57 ttl-security command RC-6 RC-57 See neighbor group command timers command RC-69 clear ospf command RC-56 send-buffer-size command RC-45 clear bgp flap-statistics route-policy command dmz-link-bandwidth command local-as command RC-56 RC-56 ebgp-multihop command RC-36 RC-34 BGP update groups example circuit-type command RC-5 bgp neighbor group submode RC-33 RC-67 soft-reconfiguration inbound always command bgp neighbor command RC-32 RC-37 bgp session group submode RC-61 send-community-ebgp command RC-40 See router bgp command RC-63 route-reflector-client command weight command RC-41 bgp bestpath med missing-as-worst command RC-42 redistribute command RC-45 distance bgp command RC-37 RC-56 RC-54 RC-121 RC-51 Index distance command show bgp reexp command RC-121 dmz-link-bandwidth command RC-56 Draft-ietf-idr-bgp4-24.txt, BGP RC-80, RC-244 Draft-ietf-idr-bgp4-mib-15.txt, BGP draft-ietf-idr-cease-subcode-05.txt RC-74 show bgp summary command RC-75 show isis adjacency command RC-101 show isis adjacency-log command RC-80 show isis command RC-80 Draft-ietf-isis-igp-p2p-over-lan-05.txt, Point-to-point operation over LAN RC-124 RC-93 show isis database command RC-105 show isis database-log command Draft-ietf-isis-ipv6-05.txt, Routing IPv6 with IS-IS RC-124 show isis interface command show isis lsp-log command Draft-ietf-isis-restart-04.txt, Restart Signalling for IS-IS RC-124 RC-101 show isis mpls command RC-105 RC-116 RC-105 RC-112 Draft-ietf-isis-traffic-05.txt, IS-IS Extensions for Traffic Engineering RC-124 show isis mpls traffic-eng adjacency-log command RC-112 Draft-ietf-isis-wg-multi-topology-06.txt, M-ISIS show isis mpls traffic-eng advertisements command RC-112 Multi Topology (MT) Routing in IS-IS RC-124 show isis neighbors command show isis spf-log command E RC-118 show isis topology command ebgp-multihop command end-policy command EXEC mode RC-116 RC-97 show running-config command RC-56 RC-107 RC-30 G RC-13 clear bgp flap statistics command RC-50 clear bgp flap statistics reexp command clear bgp flap statistics route-policy command clear bgp soft in command clear ospfv3 command RC-51 RC-71 clear bgp soft out command clear ospf command graceful-restart helper command RC-51 RC-142 graceful-restart interval command RC-142 graceful-restart lifetime command RC-142 RC-72 H RC-181 RC-181 show bgp af-group command RC-12, RC-13 show bgp cidr-only command RC-74 show bgp community command RC-74 show bgp count-only command RC-74 show bgp flap-statistics command show bgp neighbor command show bgp paths command RC-152 RC-114 RC-114 hello-password command RC-110, RC-115 RC-50 RC-50 I RC-12 ignore-lsp-errors command RC-11 show bgp neighbor-group command show bgp neighbors command hello interval (OSPF) command hello-padding command show bgp flap statistics route-policy command show bgp inheritance command RC-114 hello-multiplier command RC-50 show bgp flap statistics reexp command hello-interval (IS-IS) command RC-74 RC-75 RC-14, RC-75 RC-104 inheritance configurations (BGP) monitoring RC-7 RC-11 Cisco IOS XR Routing Configuration Guide RC-259 Index interior routers configuring RC-134 IPv6 overload bit IS-IS support configuring multitopology RIB support on router RC-88 single-topology routing authentication, configuring RC-108 configuring RC-87 isis router submode router isis command configuration ispf command RC-85 Level 1 or Level 2 routing RC-100 RC-117 ispf startup-delay command RC-91 is-type command RC-117 RC-92 RC-98 RC-84 single topology default routes L RC-93 customizing routes RC-119 link-state advertisement (LSA) RC-90 RC-83 RC-91, RC-250, RC-251, RC-253 enabling multicast-intact functional overview IPv6 routing RC-137 OSPFv3 RC-129, RC-137, RC-143 RC-56 log adjacency changes command lsp-check-interval command RC-85 controlling Level 1 or Level 2 routing, configuration RC-91 LSP flooding RC-87 RC-86 mesh group configuration RC-87 on specific interfaces RC-86 lsp-interval command configuring RC-110 description RC-89 lsp-mtu command multitopology, configuring nonstop forwarding RC-103 RC-104 RC-103 lsp-password command RC-89 RC-87 RC-87 lsp-gen-interval command MPLS TE multi-instance IS-IS RC-103 RC-102 lifetime maximum limiting RC-102 lifetime maximum RC-114, RC-147 LSP flooding RC-86 controlling OSPFv2 local-as command RC-118 RC-85 grouped configuration limiting RC-93 IPv6 support RC-85 multitopology RC-116 single-topology Cisco IOS and Cisco IOS XR software differences, configuration grouped configuration RC-84 single topology RC-90 enabling set SPF interval RC-113 attached bit on an instance description RC-234 restrictions, configuring adjacencies, tuning restrictions RC-89 redistribute RC-197 RC-86 grouped RC-87 policy attach points RC-87 IS-IS (Intermediate System-to-Intermediate System) RC-109 lsp-refresh-interval command RC-98 RC-88 Cisco IOS XR Routing Configuration Guide RC-260 RC-106 RC-103 Index nsf interface-expires command M nsf interface-timer command maximum-paths command RC-121 nsf interval command RC-175 max-lsp-lifetime command RC-103 nsf lifetime command RC-107 mesh-group command RC-104 message-digest-key command metric-style wide command nsg enforce global command RC-156 nssa command RC-110 OSPFv2 mpls traffic-eng command network command RC-152 RC-149 stub command RC-21 RC-165 RC-149 ospf area submode multitopology authentication message-digest command RC-98 virtual-link command RC-123 ospf interface configuration submode N neighbor command NBMA networks neighbor command (OSPFv2, OSPFv3) neighbor-group command RC-153 RC-56 not-so-stubby area RC-133 RC-106 enabling RC-173 RC-150 RC-180 RC-127 Designate Router (DR) RC-65 nonstop forwarding, configuring (OSPFv2) nsf command description RC-42, RC-152 RC-131 RC-175 configuration and operation, verifying RC-3 RC-131 configuration neighbors, nonbroadcast networks RC-92, RC-251, RC-252, RC-254 next-hop-self command CLI (command-line interface) inheritance MPLS TE RC-136 maximum limits (BGP) RC-155 Cisco IOS XR OSPFv3 and OSPFv2 differences neighbors network command RC-153 authentication, configuring RC-5 RC-5 adjacency (OSPFv2) RC-147 OSPFv2 (Open Shortest Path First Version 2) RC-135 neighbor address family command neighbor command RC-162 RC-162 log adjacency changes net command RC-152 RC-146 range command RC-89 multiprotocol BGP RC-149 interface command nssa command RC-144 multi-instance IS-IS RC-152 hello interval command RC-112, RC-177 RC-90 example O default-cost command RC-111 multicast-intact configuring RC-149 dead-interval command RC-176 mpls traffic-eng router-id command OSPFv2 RC-174 ospf area configuration submode RC-175 mpls traffic-eng area command IS-IS RC-107 RC-112 MPLS TE (Multiprotocol Label Switching traffic engineering) configuring IS-IS RC-107 RC-136 RC-145 functional overview instance and router ID RC-129 RC-134 LSA controlling the frequency RC-158 Cisco IOS XR Routing Configuration Guide RC-261 Index on an OSPF ABR types configuration and operation, verifying RC-164 description RC-137 MD5 authentication enabling RC-135 MPLS TE, configuring neighbors, adjacency RC-127 RC-145 functional overview RC-175 RC-129 instance and router ID RC-136 neighbors, nonbroadcast networks, configuring RC-150 nonstop forwarding load balancing RC-134 RC-141 LSA configuring RC-173 controlling frequency description RC-140 on an OSPF ABR policy attach points default originate redistribute types RC-164 RC-137 nonbroadcast networks, configuring route authentication methods MD5 RC-158 neighbors RC-231 RC-231, RC-233 key rollover RC-180 RC-150 policy attach points default originate RC-136 redistribute RC-135 RC-232 RC-231, RC-233 plain text RC-135 routes, redistribute strategies RC-136 SPF (Shortest Path First) throttling configuring route redistribution RC-166 stub and not-so-stubby area types, configuring configuring RC-166 description RC-139 virtual link, description ospfv3 area configuration submode Shortest Path First (SPF) throttling dead-interval command configuring RC-170 default-cost command description RC-139 hello interval command stub and not-so-stubby area types, configuring RC-147 supported OSPF network types NBMA networks virtual link adjacency RC-138 OSPFv2 (Open Shortest Path Fisrt version 2) enabling multicast-intact RC-149 RC-165 RC-170 log adjacency changes RC-131 overload bit configuration RC-131 configuration SPF throttling RC-143 neighbor command RC-131 on router neighbors, nonbroadcast networks RC-141 RC-186 ospfv3 interface configuration submode Cisco IOS XR OSPFv3 and OSPFv2 differences CLI inheritance RC-149 displaying information RC-186 OSPFv3 (Open Shortest Path First Version 3) RC-150 RC-170 Cisco IOS XR Routing Configuration Guide RC-262 RC-152 OSPFv3 Graceful Restart feature RC-160 addresses, importing RC-152 network command stub command transit area RC-149 RC-146 range command RC-135 RC-152 interface command nssa command RC-135 point to point networks creating RC-138 RC-87 RC-89 RC-147 RC-153 RC-170 RC-147 Index RFC 3065, Autonomous System Confederations for BGP RC-81 P password accept command password-disable command point-to-point networks RFC 3277, IS-IS Transient Blackhole Avoidance RC-57 RFC 3373, Three-Way Handshake for IS-IS Point-to-Point Adjacencies RC-125 RC-57 RC-135 RFC 3392, Capabilities Advertisement with BGP-4 policy, modifying attached RFC 3567, IS-IS Cryptopgraphic Authentication RC-235 nonattached RC-125 RFC 3623, OSPFv3 RC-235 RC-81 RC-125 RC-193 RIB (Routing Information Base) administrative distance R range command RC-197 data structures in BGP and other protocols deploying RC-165 receive-buffer-size command redistribute command examples RC-47, RC-168 redistribute isis command RC-200 RC-196 IPv4 and IPv6 support RC-104 retransmit-throttle-interval command RC-195 functional overview RC-121 retransmit-interval command RC-198 description RC-57 monitoring RC-104 RC-197 RC-198 prerequisites RFC 1142, OSI IS-IS Intra-domain Routing Protocol RC-125 RC-196 route dampening RC-23 RFC 1195, Use of OSI IS-IS for Routing in TCP/IP and Dual Environments RC-125 route-policy (BGP) command RFC 1587, Not So Stubby Area (NSSA) route-policy pass-all command RFC 1793, OSPF over demand circuit RFC 1997, BGP Communities Attribute RFC 2328, OSPF Version 2 RC-193 RC-193 RC-80 RFC 2545, Use of BGP-4 Multiprotocol Extensions for IPv6 Inter-Domain Routing RC-80 RC-193 RFC 2740 OSPFv3 RC-130 RC-29 RC-30 router bgp command RC-5 router bgp neighbor group address family configuration mode address family command RC-6 route redistribution (OSPFv2, OSPFv3) route-reflector-client command RFC 2763, Dynamic Hostname Exchange Mechanism for IS-IS RC-125 RFC 2796, BGP Route Reflection - An Alternative to Full Mesh IBGP RC-80 route reflectors router-id command RC-146 default-information originate command distance command RFC 2918, Route Refresh Capability for BGP-4 RC-80 ispf command RC-125 RC-61 router isis address family submode RC-80 RFC 2966, Domain-wide Prefix Distribution with Two-Level IS-IS RC-125 RC-139 RC-24 RFC 2858, Multiprotocol Extensions for BGP-4 RFC 2973, IS-IS Mesh Groups RC-16 See route-policy command RFC 2385, Protection of BGP Sessions via the TCP MD5 Signature Option RC-80 RFC 2740, OSPFv3 RC-31, RC-63 RC-29, RC-62 end-policy command RC-130, RC-193 RFC 2439, BGP Route Flap Damping route-policy command route policy submode RC-80 RC-196 RC-121 RC-121 RC-117 ispf startup-delay command maximum-paths command metric-style wide command RC-117 RC-121 RC-112 Cisco IOS XR Routing Configuration Guide RC-263 Index mpls traffic-eng command retransmit-throttle-interval command RC-111 mpls traffic-eng router-id command RC-112 router isis interface submode mesh-group command redistribute isis command RC-121 set-attached-bit command RC-122 router ospf command single-topology command RC-96 router ospf configuration submode spf-interval command summary-prefix command router isis command area command RC-117 router isis configuration submode RC-92 log adjacency changes command lsp-gen-interval command lsp-mtu command RC-114 RC-103 RC-103 max-lsp-lifetime command RC-103 RC-103 net command RC-92, RC-251, RC-252, RC-254 nsf command RC-106 RC-176 nsf interval command RC-175 redistribute command RC-168 router-id command nsf interface-timer command RC-107 RC-107 RC-146 summary-prefix command RC-169 timers lsa gen-interval command RC-159 RC-160 timers throttle spf command RC-159 RC-171 router ospf configuration submode command nsf command RC-174 RC-120 router isis interface configuration submode address-family command nsf enforce global RC-174 router ospfv3 command RC-146 router ospfv3 configuration submode RC-107 set-overload-bit command RC-97 area command RC-146 redistribute command router-id command RC-168 RC-146 summary-prefix command RC-97 RC-169 csnp-interval command RC-104 timers lsa gen-interval command hello-interval command RC-114 timers lsa group-pacing command hello-multiplier command hello-padding command RC-114 RC-114 hello-password command RC-110, RC-115 timers lsa min-interval command timers throttle spf command RC-95 customizing (IS-IS) ipv6 address command RC-95 default IS-IS lsp-interval command RC-104 redistribute (OSPFv2, OSPFv3) mesh-group command RC-104 redistribute IS-IS routes example Cisco IOS XR Routing Configuration Guide RC-159 RC-119 RC-95 RC-104 RC-160 RC-171 ipv6 enable command retransmit-interval command RC-159 routes ipv4 address command RC-264 RC-177 router ospf submode nsf interface-expires command circuit-type command RC-156 timers lsa min-interval command RC-109 lsp-refresh-interval command nsf lifetime command RC-156 timers lsa group-pacing command RC-103 lsp-password command RC-146 mpls traffic-eng router-id command RC-104 lsp-check-interval command RC-146 mpls traffic-eng area command RC-96 ignore-lsp-errors command is-type command RC-146 message-digest-key command RC-100 address-family command RC-104 authentication command RC-121 RC-104 RC-90 routing components RC-166 RC-123 Index Area Border Routers (ABRs) statement processing RC-134 Autonomous System Boundary Routers (ASBRs) RC-134 autonomous systems backbone area RC-209 extended community set, inline form RC-24 RC-210 extended community set, named form RC-16 names RC-238 configuration elements, editing RC-207 prefix-set RC-235 sets RC-209 RC-210 RC-207 RC-237 defining (example) enforcing, BGP RC-241 S RC-16 implementing send-buffer-size command prerequisites RC-206 inbound (example) modifying RC-240 RC-243 statements RC-221 disposition RC-220 RC-221 Boolean operators, types set-overload-bit command RC-120 show bgp af-group command RC-12, RC-13 show bgp cidr-only command RC-74 show bgp community command RC-74 show bgp count-only command RC-74 show bgp inheritance command RC-222 show bgp neighbor command RC-211 RC-50 show bgp neighbors command policy attributes modification RC-50 RC-216 parameterization Boolean operator precedence configuration basics RC-217 RC-75 show bgp reexp command RC-74 RC-201 RC-101 show isis adjacency-log command show isis command RC-13 RC-75 show ip route connected command show isis adjacency command RC-14, RC-75 RC-74 show bgp paths command show bgp summary command RC-215 RC-213 default drop disposition RC-213 RC-11 show bgp session-group command RC-214 RC-50 RC-12 show bgp neighbor-group command RC-206 definitions RC-122 show bgp flap-statistics route-policy command RPL (routing policy language) overview set-attached-bit command show bgp flap-statistics reexp command RC-219 components RC-67 show bgp flap-statistics command RC-221 remark RC-57 send-community-ebgp command RC-242 modular inbound (example) if RC-209 community-set, named set form attaching to BGP neighbor elseif RC-208 community-set, inline set form RC-133 routing domain confederation defining RC-208 as-path-set, named set form RC-133 routing policy RC-218 as-path-set, inline set form RC-136 RC-134 not-so-stubby area RC-219 structure RC-133 interior routers action verification RC-132 Designated Router (DR) stub area statements, types RC-217 RC-101 RC-93 Cisco IOS XR Routing Configuration Guide RC-265 Index show isis database command show isis database-log command show isis interface command show isis lsp-log command show isis mpls command timers lsa min-interval command RC-105 timers throttle spf command RC-105 ttl-security command RC-116 update groups show isis mpls traffic-eng advertisements command RC-112 show isis neighbors command show isis spf-log command BGP configuration monitor use command RC-70 virtual link transit area (OSPFv2) RC-96 configuring example virtual-link command RC-122 spf-interval command RC-69 RC-117 SPF throttling, configuring OSPFv2 (Open Shortest Path First Version 2) RC-170 static route Cisco IOS static route and Cisco IOS XR static route differences RC-247 RC-133 stub area types, configuring (OSPFv3) RC-147 RC-149 summary-prefix command RC-121, RC-169 T table-policy command timers bgp command timers command RC-53 RC-34 RC-57 timers lsa gen-interval command timers lsa group-pacing command RC-159 RC-160 Cisco IOS XR Routing Configuration Guide RC-266 RC-162 W RC-116 soft-reconfiguration inbound always command stub command RC-138 RC-87 set SPF interval stub area RC-58 V RC-107 single-topology IPv6 support RC-57 RC-162 show running-config command command RC-18 RC-75 update-source command RC-97 RC-162 shutdown command RC-18 BGP update generation RC-116 RC-118 show isis topology command show ospfv3 command RC-57 U show isis mpls traffic-eng adjacency-log command RC-112 show ospf command RC-171 RC-105 RC-112 weight command RC-39 RC-159
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