| Download: |  |
| Mirror Download [FCC.gov] | |
| Document ID | 3733667 |
| Application ID | Qs/zIxu1qZReeoecl9bV1A== |
| Document Description | Users Manual Part 2.pdf |
| Short Term Confidential | No |
| Permanent Confidential | No |
| Supercede | No |
| Document Type | User Manual |
| Display Format | Adobe Acrobat PDF - pdf |
| Filesize | 379.63kB (4745436 bits) |
| Date Submitted | 2018-01-30 00:00:00 |
| Date Available | 2018-07-29 00:00:00 |
| Creation Date | 2018-01-23 16:00:59 |
| Producing Software | Acrobat Distiller 11.0 (Windows) |
| Document Lastmod | 2018-01-23 16:00:59 |
| Document Title | Users Manual Part 2.pdf |
| Document Creator | FrameMaker 12.0.2 |
Chapter 9 Applications
9.6 UPnP Screen
Use this screen to enable UPnP on your EMG2881-T20A.
Click Configuration > Applications > UPnP to display the screen shown next.
Figure 46 Configuration > Applications > UPnP
The following table describes the fields in this screen.
Table 37 Configuration > Applications > UPnP
LABEL
DESCRIPTION
UPnP
Select Enable to activate UPnP. Be aware that anyone could use a UPnP application to
open the web configurator's login screen without entering the EMG2881-T20A's IP address
(although you must still enter the password to access the web configurator).
Apply
Click Apply to save the setting to the EMG2881-T20A.
Cancel
Click Cancel to return to the previously saved settings.
9.7 Technical Reference
The following section contains additional technical information about the EMG2881-T20A features
described in this chapter.
IEEE 802.1Q Tag
The IEEE 802.1Q standard defines an explicit VLAN tag in the MAC header to identify the VLAN
membership of a frame across bridges. A VLAN tag includes the 12-bit VLAN ID and 3-bit user priority.
The VLAN ID associates a frame with a specific VLAN and provides the information that devices need to
process the frame across the network.
IEEE 802.1p specifies the user priority field and defines up to eight separate traffic types. The following
table describes the traffic types defined in the IEEE 802.1d standard (which incorporates the 802.1p).
Table 38 IEEE 802.1p Priority Level and Traffic Type
PRIORITY
LEVEL
TRAFFIC TYPE
Level 7
Typically used for network control traffic such as router configuration messages.
Level 6
Typically used for voice traffic that is especially sensitive to jitter (jitter is the variations in delay).
Level 5
Typically used for video that consumes high bandwidth and is sensitive to jitter.
Level 4
Typically used for controlled load, latency-sensitive traffic such as SNA (Systems Network
Architecture) transactions.
Level 3
Typically used for “excellent effort” or better than best effort and would include important business
traffic that can tolerate some delay.
Level 2
This is for “spare bandwidth”.
EMG2881-T20A User’s Guide
83
Chapter 9 Applications
Table 38 IEEE 802.1p Priority Level and Traffic Type
PRIORITY
LEVEL
TRAFFIC TYPE
Level 1
This is typically used for non-critical “background” traffic such as bulk transfers that are allowed but
that should not affect other applications and users.
Level 0
Typically used for best-effort traffic.
DiffServ
QoS is used to prioritize source-to-destination traffic flows. All packets in the flow are given the same
priority. You can use CoS (class of service) to give different priorities to different packet types.
DiffServ (Differentiated Services) is a class of service (CoS) model that marks packets so that they
receive specific per-hop treatment at DiffServ-compliant network devices along the route based on the
application types and traffic flow. Packets are marked with DiffServ Code Points (DSCPs) indicating the
level of service desired. This allows the intermediary DiffServ-compliant network devices to handle the
packets differently depending on the code points without the need to negotiate paths or remember
state information for every flow. In addition, applications do not have to request a particular service or
give advanced notice of where the traffic is going.
DSCP and Per-Hop Behavior
DiffServ defines a new Differentiated Services (DS) field to replace the Type of Service (TOS) field in the IP
header. The DS field contains a 2-bit unused field and a 6-bit DSCP field which can define up to 64
service levels. The following figure illustrates the DS field.
DSCP is backward compatible with the three precedence bits in the ToS octet so that non-DiffServ
compliant, ToS-enabled network device will not conflict with the DSCP mapping.
DSCP (6 bits)
Unused (2 bits)
The DSCP value determines the forwarding behavior, the PHB (Per-Hop Behavior), that each packet
gets across the DiffServ network. Based on the marking rule, different kinds of traffic can be marked for
different kinds of forwarding. Resources can then be allocated according to the DSCP values and the
configured policies.
IP Precedence
Similar to IEEE 802.1p prioritization at layer-2, you can use IP precedence to prioritize packets in a layer-3
network. IP precedence uses three bits of the eight-bit ToS (Type of Service) field in the IP header. There
are eight classes of services (ranging from zero to seven) in IP precedence. Zero is the lowest priority
level and seven is the highest.
Automatic Priority Queue Assignment
If you enable QoS on the EMG2881-T20A, the EMG2881-T20A can automatically base on the IEEE 802.1p
priority level, IP precedence and/or packet length to assign priority to traffic which does not match a
class.
EMG2881-T20A User’s Guide
84
Chapter 9 Applications
The following table shows you the internal layer-2 and layer-3 QoS mapping on the EMG2881-T20A. On
the EMG2881-T20A, traffic assigned to higher priority queues gets through faster while traffic in lower
index queues is dropped if the network is congested.
Table 39 Internal Layer2 and Layer3 QoS Mapping
LAYER 2
LAYER 3
PRIORITY
QUEUE
IEEE 802.1P USER
PRIORITY
(ETHERNET
PRIORITY)
TOS (IP
PRECEDENCE)
DSCP
000000
000000
>1100
001110
250~1100
IP PACKET LENGTH
(BYTE)
001100
001010
001000
010110
010100
010010
010000
011110
<250
011100
011010
011000
100110
100100
100010
100000
101110
110000
111000
101000
Token Bucket
The token bucket algorithm uses tokens in a bucket to control when traffic can be transmitted. The
bucket stores tokens, each of which represents one byte. The algorithm allows bursts of up to b bytes
which is also the bucket size, so the bucket can hold up to b tokens. Tokens are generated and added
into the bucket at a constant rate. The following shows how tokens work with packets:
• A packet can be transmitted if the number of tokens in the bucket is equal to or greater than the size
of the packet (in bytes).
• After a packet is transmitted, a number of tokens corresponding to the packet size is removed from
the bucket.
EMG2881-T20A User’s Guide
85
Chapter 9 Applications
• If there are no tokens in the bucket, the EMG2881-T20A stops transmitting until enough tokens are
generated.
• If not enough tokens are available, the EMG2881-T20A treats the packet in either one of the following
ways:
In traffic shaping:
• Holds it in the queue until enough tokens are available in the bucket.
In traffic policing:
• Drops it.
• Transmits it but adds a DSCP mark. The EMG2881-T20A may drop these marked packets if the
network is overloaded.
Configure the bucket size to be equal to or less than the amount of the bandwidth that the interface
can support. It does not help if you set it to a bucket size over the interface’s capability. The smaller the
bucket size, the lower the data transmission rate and that may cause outgoing packets to be dropped.
A larger transmission rate requires a big bucket size. For example, use a bucket size of 10 kbytes to get
the transmission rate up to 10 Mbps.
Single Rate Three Color Marker
The Single Rate Three Color Marker (srTCM, defined in RFC 2697) is a type of traffic policing that identifies
packets by comparing them to one user-defined rate, the Committed Information Rate (CIR), and two
burst sizes: the Committed Burst Size (CBS) and Excess Burst Size (EBS).
The srTCM evaluates incoming packets and marks them with one of three colors which refer to packet
loss priority levels. High packet loss priority level is referred to as red, medium is referred to as yellow and
low is referred to as green.
The srTCM is based on the token bucket filter and has two token buckets (CBS and EBS). Tokens are
generated and added into the bucket at a constant rate, called Committed Information Rate (CIR).
When the first bucket (CBS) is full, new tokens overflow into the second bucket (EBS).
All packets are evaluated against the CBS. If a packet does not exceed the CBS it is marked green.
Otherwise it is evaluated against the EBS. If it is below the EBS then it is marked yellow. If it exceeds the
EBS then it is marked red.
The following shows how tokens work with incoming packets in srTCM:
• A packet arrives. The packet is marked green and can be transmitted if the number of tokens in the
CBS bucket is equal to or greater than the size of the packet (in bytes).
• After a packet is transmitted, a number of tokens corresponding to the packet size is removed from
the CBS bucket.
• If there are not enough tokens in the CBS bucket, the EMG2881-T20A checks the EBS bucket. The
packet is marked yellow if there are sufficient tokens in the EBS bucket. Otherwise, the packet is
marked red. No tokens are removed if the packet is dropped.
Two Rate Three Color Marker
The Two Rate Three Color Marker (trTCM, defined in RFC 2698) is a type of traffic policing that identifies
packets by comparing them to two user-defined rates: the Committed Information Rate (CIR) and the
Peak Information Rate (PIR). The CIR specifies the average rate at which packets are admitted to the
EMG2881-T20A User’s Guide
86
Chapter 9 Applications
network. The PIR is greater than or equal to the CIR. CIR and PIR values are based on the guaranteed
and maximum bandwidth respectively as negotiated between a service provider and client.
The trTCM evaluates incoming packets and marks them with one of three colors which refer to packet
loss priority levels. High packet loss priority level is referred to as red, medium is referred to as yellow and
low is referred to as green.
The trTCM is based on the token bucket filter and has two token buckets (Committed Burst Size (CBS)
and Peak Burst Size (PBS)). Tokens are generated and added into the two buckets at the CIR and PIR
respectively.
All packets are evaluated against the PIR. If a packet exceeds the PIR it is marked red. Otherwise it is
evaluated against the CIR. If it exceeds the CIR then it is marked yellow. Finally, if it is below the CIR then
it is marked green.
The following shows how tokens work with incoming packets in trTCM:
• A packet arrives. If the number of tokens in the PBS bucket is less than the size of the packet (in bytes),
the packet is marked red and may be dropped regardless of the CBS bucket. No tokens are removed
if the packet is dropped.
• If the PBS bucket has enough tokens, the EMG2881-T20A checks the CBS bucket. The packet is
marked green and can be transmitted if the number of tokens in the CBS bucket is equal to or greater
than the size of the packet (in bytes). Otherwise, the packet is marked yellow.
9.7.1 Using UPnP in Windows XP Example
This section shows you how to use the UPnP feature in Windows XP. You must already have UPnP installed
in Windows XP and UPnP activated on the EMG2881-T20A.
Make sure the computer is connected to a LAN port of the EMG2881-T20A. Turn on your computer and
the EMG2881-T20A.
9.7.1.1 Auto-discover Your UPnP-enabled Network Device
Click start and Control Panel. Double-click Network Connections. An icon displays under Internet
Gateway.
Right-click the icon and select Properties.
Figure 47 Network Connections
EMG2881-T20A User’s Guide
87
Chapter 9 Applications
In the Internet Connection Properties window, click Settings to see the port mappings there were
automatically created.
Figure 48 Internet Connection Properties
You may edit or delete the port mappings or click Add to manually add port mappings.
Figure 49 Internet Connection Properties: Advanced Settings
Figure 50 Internet Connection Properties: Advanced Settings: Add
Note: When the UPnP-enabled device is disconnected from your computer, all port
mappings will be deleted automatically.
EMG2881-T20A User’s Guide
88
Chapter 9 Applications
Select Show icon in notification area when connected option and click OK. An icon displays in the
system tray.
Figure 51 System Tray Icon
Double-click on the icon to display your current Internet connection status.
Figure 52 Internet Connection Status
9.7.2 Web Configurator Easy Access
With UPnP, you can access the web-based configurator on the EMG2881-T20A without finding out the IP
address of the EMG2881-T20A first. This comes helpful if you do not know the IP address of the EMG2881T20A.
Follow the steps below to access the web configurator.
Click Start and then Control Panel.
Double-click Network Connections.
Select My Network Places under Other Places.
EMG2881-T20A User’s Guide
89
Chapter 9 Applications
Figure 53 Network Connections
An icon with the description for each UPnP-enabled device displays under Local Network.
Right-click on the icon for your EMG2881-T20A and select Invoke. The web configurator login screen
displays.
Figure 54 Network Connections: My Network Places
Right-click on the icon for your EMG2881-T20A and select Properties. A properties window displays with
basic information about the EMG2881-T20A.
EMG2881-T20A User’s Guide
90
Chapter 9 Applications
Figure 55 Network Connections: My Network Places: Properties: Example
EMG2881-T20A User’s Guide
91
C H A P T E R 10
Security
10.1 Overview
Use these screens to enable and configure the firewall that protects your EMG2881-T20A and your LAN
from unwanted or malicious traffic.
Enable the firewall to protect your LAN computers from attacks by hackers on the Internet and control
access between the LAN and WAN. By default the firewall:
• allows traffic that originates from your LAN computers to go to all of the networks.
• blocks traffic that originates on the other networks from going to the LAN.
The following figure illustrates the default firewall action. User A can initiate an IM (Instant Messaging)
session from the LAN to the WAN (1). Return traffic for this session is also allowed (2). However other traffic
initiated from the WAN is blocked (3 and 4).
Figure 56 Default Firewall Action
10.1.1 What You Can Do
• Use the IPv4 Firewall screen to enable or disable the EMG2881-T20A’s IPv4 firewall (Section 10.2 on
page 93).
• Use the IPv6 Firewall screen to enable or disable the EMG2881-T20A’s IPv6 firewall (Section 10.3 on
page 95).
10.1.2 What You Need To Know
The following terms and concepts may help as you read through this chapter.
EMG2881-T20A User’s Guide
92
Chapter 10 Security
About the EMG2881-T20A Firewall
The EMG2881-T20A’s firewall feature physically separates the LAN and the WAN and acts as a secure
gateway for all data passing between the networks.
It is a stateful inspection firewall and is designed to protect against Denial of Service attacks when
activated (click the IPv4 Firewall or IPv6 Firewall tab under Security and then click the Enable Firewall
check box). The EMG2881-T20A's purpose is to allow a private Local Area Network (LAN) to be securely
connected to the Internet. The EMG2881-T20A can be used to prevent theft, destruction and
modification of data, as well as log events, which may be important to the security of your network.
The EMG2881-T20A is installed between the LAN and a broadband modem connecting to the Internet.
This allows it to act as a secure gateway for all data passing between the Internet and the LAN.
The EMG2881-T20A has one Ethernet WAN port and four Ethernet LAN ports, which are used to physically
separate the network into two areas.The WAN (Wide Area Network) port attaches to the broadband
(cable or DSL) modem to the Internet.
The LAN (Local Area Network) port attaches to a network of computers, which needs security from the
outside world. These computers will have access to Internet services such as e-mail, FTP and the World
Wide Web. However, "inbound access" is not allowed (by default) unless the remote host is authorized to
use a specific service.
Guidelines For Enhancing Security With Your Firewall
Change the default password via Web Configurator.
Think about access control before you connect to the network in any way, including attaching a
modem to the port.
Limit who can access your router.
Don't enable any local service (such as NTP) that you don't use. Any enabled service could present a
potential security risk. A determined hacker might be able to find creative ways to misuse the enabled
services to access the firewall or the network.
For local services that are enabled, protect against misuse. Protect by configuring the services to
communicate only with specific peers, and protect by configuring rules to block packets for the services
at specific interfaces.
Protect against IP spoofing by making sure the firewall is active.
Keep the firewall in a secured (locked) room.
10.2 IPv4 Firewall Screen
Use this screen to enable or disable the EMG2881-T20A’s IPv4 firewall. Click Configuration > Security >
IPv4 Firewall to open the firewall setup screen.
EMG2881-T20A User’s Guide
93
Chapter 10 Security
Figure 57 Configuration > Security > IPv4 Firewall
The following table describes the labels in this screen.
Table 40 Configuration > Security > IPv4 Firewall
LABEL
DESCRIPTION
ICMP
Internet Control Message Protocol is a message control and error-reporting protocol between
a host server and a gateway to the Internet. ICMP uses Internet Protocol (IP) datagrams, but
the messages are processed by the TCP/IP software and directly apparent to the application
user.
Respond to Ping
on
The EMG2881-T20A will not respond to any incoming Ping requests when Disable is selected.
Select LAN to reply to incoming LAN Ping requests. Select WAN to reply to incoming WAN Ping
requests. Otherwise select LAN&WAN to reply to all incoming LAN and WAN Ping requests.
Firewall Setup
Enable Firewall
Select this check box to activate the firewall. The EMG2881-T20A performs access control and
protects against Denial of Service (DoS) attacks when the firewall is activated.
Enable Firewall Rule
Enable Firewall
Rule
Select this check box to activate the firewall rules that you define (see Add Firewall Rule
below).
Filter table type
Select DROP to silently discard the packets which meet the firewall rules. The others are
accepted.
Select ACCEPT to allow the passage of the packets which meet the firewall rules. The others
are blocked.
Add Firewall Rule
Service Name
Enter a name that identifies or describes the firewall rule.
MAC Address
Enter the MAC address of the computer for which the firewall rule applies.
EMG2881-T20A User’s Guide
94
Chapter 10 Security
Table 40 Configuration > Security > IPv4 Firewall (continued)
LABEL
DESCRIPTION
Dest IP Address
Enter the IP address of the computer to which traffic for the application or service is entering.
The EMG2881-T20A applies the firewall rule to traffic initiating from this computer.
Source IP Address
Enter the IP address of the computer that initializes traffic for the application or service.
The EMG2881-T20A applies the firewall rule to traffic initiating from this computer.
Protocol
Select the protocol (TCP, UDP or ICMP) used to transport the packets for which you want to
apply the firewall rule.
Dest Port Range
This is the port number/range of the destination that define the traffic type, for example TCP
port 80 defines web traffic.
Source Port Range
This is the port number/range of the source that define the traffic type, for example TCP port
80 defines web traffic.
Add Rule
Click Add Rule to save the firewall rule.
Firewall Rule
This is your firewall rule number. The ordering of your rules is important as rules are applied in
turn.
Service Name
This is a name that identifies or describes the firewall rule.
MAC address
This is the MAC address of the computer for which the firewall rule applies.
Dest IP
This is the IP address of the computer to which traffic for the application or service is entering.
Source IP
This is the IP address of the computer from which traffic for the application or service is
initialized.
Protocol
This is the protocol (TCP, UDP or ICMP) used to transport the packets for which you want to
apply the firewall rule.
Dest Port Range
This is the port number/range of the destination that define the traffic type, for example TCP
port 80 defines web traffic.
Source Port Range
This is the port number/range of the source that define the traffic type, for example TCP port
80 defines web traffic.
Delete
Click
Apply
Click Apply to save the settings.
to remove the firewall rule.
Cancel
Click Cancel to start configuring this screen again.
10.3 IPv6 Firewall Screen
This chapter shows you how to enable and create IPv6 firewall rules to filter IPv6 traffic.
EMG2881-T20A User’s Guide
95
Chapter 10 Security
Click Configuration > Security > IPv6 Firewall. The IPv6 Firewall screen appears as shown.
Figure 58 Configuration > Security > IPv6 Firewall
The following table describes the labels in this screen.
Table 41 Configuration > Security > IPv6 Firewall
LABEL
DESCRIPTION
Enable Firewall Rule
Enable Firewall Rule
Select this check box to activate the firewall rules that you define (see Add Firewall Rule
below).
Filter table type
Select DROP to silently discard the packets which meet the firewall rules. The others are
accepted.
Select ACCEPT to allow the passage of the packets which meet the firewall rules. The others
are blocked.
Add Firewall Rule
Service Name
Enter a name that identifies or describes the firewall rule.
MAC Address
Enter the MAC address of the computer for which the firewall rule applies.
Dest IP Address
Enter the IPv6 address of the computer to which traffic for the application or service is
entering.
The EMG2881-T20A applies the firewall rule to traffic destined for this computer.
Source IP Address
Enter the IPv6 address of the computer that initializes traffic for the application or service.
The EMG2881-T20A applies the firewall rule to traffic initiating from this computer.
Protocol
Select the protocol (TCP, UDP or ICMPv6) used to transport the packets for which you want
to apply the firewall rule.
Dest Port Range
Enter the port number/range of the destination that defines the traffic type, for example
TCP port 80 defines web traffic.
Source Port Range
Enter the port number/range of the source that defines the traffic type, for example TCP
port 80 defines web traffic.
Add Rule
Click Add Rule to save the firewall rule.
Firewall Rule
EMG2881-T20A User’s Guide
96
Chapter 10 Security
Table 41 Configuration > Security > IPv6 Firewall (continued)
LABEL
DESCRIPTION
This is your firewall rule number. The ordering of your rules is important as rules are applied in
turn.
ServiceName
This is a name that identifies or describes the firewall rule.
MAC Address
This is the MAC address of the computer for which the firewall rule applies.
Dest IP
This is the IP address of the computer to which traffic for the application or service is
entering.
Source IP
This is the IP address of the computer to which traffic for the application or service is
initialized.
Protocol
This is the protocol (TCP, UDP or ICMPv6) used to transport the packets for which you want to
apply the firewall rule.
Dest Port Range
This is the port number/range of the destination that defines the traffic type, for example
TCP port 80 defines web traffic.
Source Port Range
This is the port number/range of the source that defines the traffic type, for example TCP
port 80 defines web traffic.
Delete
Click
to remove the firewall rule.
Apply
Click Apply to save the settings.
Cancel
Click Cancel to restore your previously saved settings.
EMG2881-T20A User’s Guide
97
C H A P T E R 11
Maintenance
11.1 Overview
This chapter provides information on the Maintenance screens.
11.2 What You Can Do
• Use the General screen to set the timeout period of the management session (Section 11.3 on page
98).
• Use the Password screen to change your EMG2881-T20A’s system password (Section 11.4 on page
99).
• Use the Time screen to change your EMG2881-T20A’s time and date (Section 11.5 on page 100).
• Use the Firmware Upgrade screen to upload firmware to your EMG2881-T20A (Section 11.6 on page
101).
• Use the Backup/Restore screen to view information related to factory defaults, backup configuration,
and restoring configuration (Section 11.8 on page 104).
• Use the Restart screen to reboot the EMG2881-T20A without turning the power off (Section 11.8 on
page 104).
• Use the Log screen to see the logs for the activity on the EMG2881-T20A (Section 11.9 on page 104).
• Use the ROMD screen to save and/or clean the configuration to/from the ROMD file which can store
customized default settings.
11.3 General Screen
Use this screen to set the management session timeout period. Click Maintenance > General. The
following screen displays.
Figure 59 Maintenance > General
EMG2881-T20A User’s Guide
98
Chapter 11 Maintenance
The following table describes the labels in this screen.
Table 42 Maintenance > General
LABEL
DESCRIPTION
System Name
System Name is a unique name to identify the EMG2881-T20A in an Ethernet network.
Domain Name
Enter the domain name you want to give to the EMG2881-T20A.
Administrator
Inactivity Timer
Type how many minutes a management session can be left idle before the session times out. The
default is 5 minutes. After it times out you have to log in with your password again. Very long idle
timeouts may have security risks. A value of "0" means a management session never times out,
no matter how long it has been left idle (not recommended).
Apply
Click Apply to save your changes back to the EMG2881-T20A.
Cancel
Click Cancel to exit this screen without saving.
11.4 Password Screen
It is strongly recommended that you change your EMG2881-T20A's password.
If you forget your EMG2881-T20A's password (or IP address), you will need to reset the device. See
Section 11.8 on page 104 for details.
Click Maintenance > Password. The screen appears as shown.
Figure 60 Maintenance > Password
The following table describes the labels in this screen.
Table 43 Maintenance > Password
LABEL
DESCRIPTION
User
This field displays the name of the admin account.
Old Password
Type the default password or the existing password you use to access the system in this
field.
New Password
Type your new system password (up to 30 characters). Note that as you type a password,
the screen displays an asterisk (*) for each character you type.
Retype to Confirm
Type the new password again in this field.
Apply
Click Apply to save your changes back to the EMG2881-T20A.
Cancel
Click Cancel to begin configuring this screen afresh.
EMG2881-T20A User’s Guide
99
Chapter 11 Maintenance
11.5 Time Screen
Use this screen to configure the EMG2881-T20A’s time based on your local time zone. To change your
EMG2881-T20A’s time and date, click Maintenance > Time. The screen appears as shown.
Figure 61 Maintenance > Time
The following table describes the labels in this screen.
Table 44 Maintenance > Time
LABEL
DESCRIPTION
Current Time and Date
Current Time
This field displays the time of your EMG2881-T20A.
Each time you reload this page, the EMG2881-T20A synchronizes the time with the time server.
Current Date
This field displays the date of your EMG2881-T20A.
Each time you reload this page, the EMG2881-T20A synchronizes the date with the time server.
Time and Date Setup
Manual
Select this radio button to enter the time and date manually. If you configure a new time and
date, Time Zone and Daylight Saving at the same time, the new time and date you entered has
priority and the Time Zone and Daylight Saving settings do not affect it.
New Time
This field displays the last updated time from the time server or the last time configured manually.
(hh:mm:ss)
When you select Manual, enter the new time in this field and then click Apply.
New Date
This field displays the last updated date from the time server or the last date configured
manually.
(yyyy/mm/dd)
When you select Manual, enter the new date in this field and then click Apply.
Get from Time
Server
Select this radio button to have the EMG2881-T20A get the time and date from the time server
you specified below.
User Defined
Time Server
Address
Enter the IP address or URL (up to 20 extended ASCII characters in length) of your time server.
Check with your ISP/network administrator if you are unsure of this information.
Time Zone Setup
Time Zone
Choose the time zone of your location. This will set the time difference between your time zone
and Greenwich Mean Time (GMT).
EMG2881-T20A User’s Guide
100
Chapter 11 Maintenance
Table 44 Maintenance > Time (continued)
LABEL
DESCRIPTION
Daylight Savings
Daylight saving is a period from late spring to early fall when many countries set their clocks
ahead of normal local time by one hour to give more daytime light in the evening.
Select this option if you use Daylight Saving Time.
Start Date
Configure the day and time when Daylight Saving Time starts if you selected Daylight Savings.
The o’clock field uses the 24 hour format. Here are a couple of examples.
Daylight Saving Time starts in most parts of the United States on the first Sunday of April. Each
time zone in the United States starts using Daylight Saving Time at 2 A.M local time. So in the
United States you would select First, Sunday, April and type 2 in the o’clock field.
Daylight Saving Time starts in the European Union on the last Sunday of March. All of the time
zones in the European Union start using Daylight Saving Time at the same moment (1 A.m. GMT
or UTC). So in the European Union you would select Last, Sunday, March. The time you type in the
o’clock field depends on your time zone. In Germany for instance, you would type 2 because
Germany’s time zone is one hour ahead of GMT or UTC (GMT+1).
End Date
Configure the day and time when Daylight Saving Time ends if you selected Daylight Savings.
The o’clock field uses the 24 hour format. Here are a couple of examples.
Daylight Saving Time ends in the United States on the last Sunday of October. Each time zone in
the United States stops using Daylight Saving Time at 2 A.M. local time. So in the United States
you would select Last, Sunday, October and type 2 in the o’clock field.
Daylight Saving Time ends in the European Union on the last Sunday of October. All of the time
zones in the European Union stop using Daylight Saving Time at the same moment (1 A.M. GMT
or UTC). So in the European Union you would select Last, Sunday, October. The time you type in
the o’clock field depends on your time zone. In Germany for instance, you would type 2
because Germany’s time zone is one hour ahead of GMT or UTC (GMT + 1).
Apply
Click Apply to save your changes back to the EMG2881-T20A.
Cancel
Click Cancel to exit this screen without saving.
11.6 Firmware Upgrade Screen
Find firmware at www.zyxel.com in a file that (usually) uses the system model name with a “*.bin”
extension, e.g., “EMG2881-T20A.bin”. The upload process uses HTTP (Hypertext Transfer Protocol) and
may take up to two minutes. After a successful upload, the system will reboot.
Click Maintenance > Firmware Upgrade. Follow the instructions in this screen to upload firmware to your
EMG2881-T20A.
Figure 62 Maintenance > Firmware Upgrade
EMG2881-T20A User’s Guide
101
Chapter 11 Maintenance
The following table describes the labels in this screen.
Table 45 Maintenance > Firmware Upgrade
LABEL
DESCRIPTION
Firmware Upgrade
File Path
Type in the location of the file you want to upload in this field or click Choose File to find it.
Choose File
Click Choose File to find the .bin file you want to upload. Remember that you must decompress
compressed (.zip) files before you can upload them.
Upload
Click Upload to begin the upload process. This process may take up to two minutes.
Do not turn off the EMG2881-T20A while firmware upload is in progress!
After you see the Firmware Upload In Process screen, wait two minutes before logging into the
EMG2881-T20A again.
The EMG2881-T20A automatically restarts in this time causing a temporary network disconnect. In some
operating systems, you may see the following icon on your desktop.
Figure 63 Network Temporarily Disconnected
After two minutes, log in again and check your new firmware version in the Status screen.
If the upload was not successful, an error message appears.
11.7 Configuration Backup/Restore Screen
Backup configuration allows you to back up (save) the EMG2881-T20A’s current configuration to a file
on your computer. Once your EMG2881-T20A is configured and functioning properly, it is highly
recommended that you back up your configuration file before making configuration changes. The
backup configuration file will be useful in case you need to return to your previous settings.
Restore configuration allows you to upload a new or previously saved configuration file from your
computer to your EMG2881-T20A.
Click Maintenance > Backup/Restore. Information related to factory defaults, backup configuration,
and restoring configuration appears as shown next.
EMG2881-T20A User’s Guide
102
Chapter 11 Maintenance
Figure 64 Maintenance > Backup/Restore
The following table describes the labels in this screen.
Table 46 Maintenance > Backup/Restore
LABEL
DESCRIPTION
Backup Configuration
Backup
Click Backup to save the EMG2881-T20A’s current configuration to your computer.
Restore Configuration
File Path
Click Choose File to browse to the location of the configuration file in your computer.
Upload
Click Upload to begin the upload process.
Note: Do not turn off the EMG2881-T20A while configuration file upload is in progress.
After you see a “configuration upload successful” screen, you must then wait one minute before
logging into the EMG2881-T20A again. The EMG2881-T20A automatically restarts in this time
causing a temporary network disconnect.
If you see an error screen, click Back to return to the Backup/Restore screen.
Reset
Pressing the Reset button in this section clears all user-entered configuration information and
returns the EMG2881-T20A to its factory defaults.
You can also press the RESET button on the rear panel to reset the factory defaults of your
EMG2881-T20A. Refer to the chapter about introducing the Web Configurator for more
information on the RESET button.
Note: If you uploaded the default configuration file you may need to change the IP address
of your computer to be in the same subnet as that of the default EMG2881-T20A IP
address (192.168.1.1). See Appendix B on page 121 for details on how to set up your
computer’s IP address.
EMG2881-T20A User’s Guide
103
Chapter 11 Maintenance
11.8 Restart Screen
System restart allows you to reboot the EMG2881-T20A without turning the power off.
Click Maintenance > Restart to open the following screen.
Figure 65 Maintenance > Restart
Click Restart to have the EMG2881-T20A reboot. This does not affect the EMG2881-T20A's configuration.
11.9 Log Screen
The Web Configurator allows you to look at all of the EMG2881-T20A’s logs in one location.
You can configure which logs to display in the Log screen. Select the logs you wish to display. Click
Apply to save your settings. Click Cancel to start the screen afresh.
Use this screen to see the logged messages for the EMG2881-T20A. The log wraps around and deletes
the old entries after it fills. Select what logs you want to see from the Display drop list. The log choices
depend on your settings above this screen. Click Refresh to renew the log screen. Click Clear Log to
delete all the logs.
Figure 66 Maintenance > Log
11.10 The ROMD Screen
Click Maintenance > ROMD to open the following screen.
EMG2881-T20A User’s Guide
104
Chapter 11 Maintenance
Figure 67 Maintenance > ROMD
Click Save to save the EMG2881-T20A’s current configuration to the ROM-D file. Click Clear to reset the
customized settings in the ROM-D file to factory defaults.
EMG2881-T20A User’s Guide
105
C H A P T E R 12
Troubleshooting
12.1 Overview
This chapter offers some suggestions to solve problems you might encounter. The potential problems are
divided into the following categories.
• Power, Hardware Connections, and LEDs
• EMG2881-T20A Access and Login
• Internet Access
• Resetting the EMG2881-T20A to Its Factory Defaults
• Wireless Connections
12.2 Power, Hardware Connections, and LEDs
The EMG2881-T20A does not turn on. None of the LEDs turn on.
Make sure you are using the power adaptor or cord included with the EMG2881-T20A.
Make sure the power adaptor or cord is connected to the EMG2881-T20A and plugged in to an
appropriate power source. Make sure the power source is turned on.
Disconnect and re-connect the power adaptor or cord to the EMG2881-T20A.
If the problem continues, contact the vendor.
One of the LEDs does not behave as expected.
Make sure you understand the normal behavior of the LED. See Section 1.5 on page 12.
Check the hardware connections. See the Quick Start Guide.
Inspect your cables for damage. Contact the vendor to replace any damaged cables.
Disconnect and re-connect the power adaptor to the EMG2881-T20A.
If the problem continues, contact the vendor.
EMG2881-T20A User’s Guide
106
Chapter 12 Troubleshooting
12.3 EMG2881-T20A Access and Login
I don’t know the IP address of my EMG2881-T20A.
The default IP address of the EMG2881-T20A in Router Mode is 192.168.1.1.
If you changed the IP address and have forgotten it, you might get the IP address of the EMG2881-T20A
in Router Mode by looking up the IP address of the default gateway for your computer. To do this in most
Windows computers, click Start > Run, enter cmd, and then enter ipconfig. The IP address of the Default
Gateway might be the IP address of the EMG2881-T20A (it depends on the network), so enter this IP
address in your Internet browser.
Reset your EMG2881-T20A to change all settings back to their default. This means your current settings
are lost. See Section 12.5 on page 109 in the Troubleshooting for information on resetting your EMG2881T20A.
I forgot the password.
The default password is the factory default (see the device label).
If this does not work, you have to reset the device to its factory defaults. See Section 12.5 on page 109.
I cannot see or access the Login screen in the Web Configurator.
Make sure you are using the correct IP address.
• The default IP address of the EMG2881-T20A in Router Mode is 192.168.1.1.
• If you changed the IP address (Section 8.4 on page 71), use the new IP address.
• If you changed the IP address and have forgotten it, see the troubleshooting suggestions for I don’t
know the IP address of my EMG2881-T20A.
Check the hardware connections, and make sure the LEDs are behaving as expected. See the Quick
Start Guide.
Make sure your Internet browser does not block pop-up windows and has JavaScript and Java
enabled. See Appendix A on page 112.
Make sure your computer is in the same subnet as the EMG2881-T20A. (If you know that there are routers
between your computer and the EMG2881-T20A, skip this step.)
• If there is a DHCP server on your network, make sure your computer is using a dynamic IP address.
See Section 8.4 on page 71.
• If there is no DHCP server on your network, make sure your computer’s IP address is in the same
subnet as the EMG2881-T20A. See Section 8.4 on page 71.
EMG2881-T20A User’s Guide
107
Chapter 12 Troubleshooting
Reset the device to its factory defaults, and try to access the EMG2881-T20A with the default IP address.
See Section 1.5.6 on page 14.
If the problem continues, contact the network administrator or vendor, or try one of the advanced
suggestions.
Advanced Suggestions
• Try to access the EMG2881-T20A using another service, such as Telnet. If you can access the
EMG2881-T20A, check the remote management settings and firewall rules to find out why the
EMG2881-T20A does not respond to HTTP.
• If your computer is connected to the WAN port or is connected wirelessly, use a computer that is
connected to a LAN/ETHERNET port.
I can see the Login screen, but I cannot log in to the EMG2881-T20A.
Make sure you have entered the password correctly. The default password is the factory default (see
the device label). This field is case-sensitive, so make sure [Caps Lock] is not on.
This can happen when you fail to log out properly from your last session. Try logging in again after 10
minutes.
Disconnect and re-connect the power adaptor or cord to the EMG2881-T20A.
If this does not work, you have to reset the device to its factory defaults. See Section 12.5 on page 109.
12.4 Internet Access
I cannot access the Internet.
Check the hardware connections, and make sure the LEDs are behaving as expected. See the Quick
Start Guide.
Make sure the WAN port is connected to a broadband modem or router with Internet access. Your
computer and the EMG2881-T20A should be in the same subnet.
Make sure you entered your ISP account information correctly in the wizard or the WAN screen. These
fields are case-sensitive, so make sure [Caps Lock] is not on.
If you are trying to access the Internet wirelessly, make sure the wireless settings in the wireless client are
the same as the settings in the AP.
Disconnect all the cables from your device, and follow the directions in the Quick Start Guide again.
If the problem continues, contact your ISP.
EMG2881-T20A User’s Guide
108
Chapter 12 Troubleshooting
I cannot access the Internet anymore. I had access to the Internet (with the EMG2881-T20A), but
my Internet connection is not available anymore.
Check the hardware connections, and make sure the LEDs are behaving as expected. See the Quick
Start Guide and Section 1.5 on page 12.
Reboot the EMG2881-T20A.
If the problem continues, contact your ISP.
The Internet connection is slow or intermittent.
There might be a lot of traffic on the network. Look at the LEDs, and check Section 1.5 on page 12. If the
EMG2881-T20A is sending or receiving a lot of information, try closing some programs that use the
Internet, especially peer-to-peer applications.
Check the signal strength. If the signal strength is low, try moving the EMG2881-T20A closer to the AP if
possible, and look around to see if there are any devices that might be interfering with the wireless
network (for example, microwaves, other wireless networks, and so on).
Reboot the EMG2881-T20A.
If the problem continues, contact the network administrator or vendor, or try one of the advanced
suggestions.
Advanced Suggestion
• Check the settings for QoS. If it is disabled, you might consider activating it.
12.5 Resetting the EMG2881-T20A to Its Factory Defaults
If you reset the EMG2881-T20A, you lose all of the changes you have made. The EMG2881-T20A re-loads
its default settings. You have to make all of your changes again.
You will lose all of your changes when you push the RESET button.
To reset the EMG2881-T20A:
Make sure the power LED is on.
Press the RESET button for one to four seconds to restart/reboot the EMG2881-T20A.
EMG2881-T20A User’s Guide
109
Chapter 12 Troubleshooting
Press the RESET button for longer than five seconds to set the EMG2881-T20A back to its factory-default
configurations.
If the EMG2881-T20A restarts automatically, wait for the EMG2881-T20A to finish restarting, and log in to
the Web Configurator. The password is reset to the factory default (see the device label).
If the EMG2881-T20A does not restart automatically, disconnect and reconnect the EMG2881-T20A’s
power. Then, follow the directions above again.
12.6 Wireless Connections
I cannot access the EMG2881-T20A or ping any computer from the WLAN.
Make sure the wireless LAN is enabled on the EMG2881-T20A.
Make sure the wireless adapter on your computer is working properly.
Make sure the wireless adapter installed on your computer is IEEE 802.11 compatible and supports the
same wireless standard as the EMG2881-T20A.
Make sure your computer (with a wireless adapter installed) is within the transmission range of the
EMG2881-T20A.
Check that both the EMG2881-T20A and the wireless adapter on your computer are using the same
wireless and wireless security settings.
Make sure traffic between the WLAN and the LAN is not blocked by the firewall on the EMG2881-T20A.
Make sure you allow the EMG2881-T20A to be remotely accessed through the WLAN interface. Check
your remote management settings.
• See the chapter on Wireless LAN in the User’s Guide for more information.
What factors may cause intermittent or unstabled wireless connection? How can I solve this
problem?
The following factors may cause interference:
• Obstacles: walls, ceilings, furniture, and so on.
• Building Materials: metal doors, aluminum studs.
• Electrical devices: microwaves, monitors, electric motors, cordless phones, and other wireless devices.
To optimize the speed and quality of your wireless connection, you can:
• Move your wireless device closer to the AP if the signal strength is low.
EMG2881-T20A User’s Guide
110
Chapter 12 Troubleshooting
• Reduce wireless interference that may be caused by other wireless networks or surrounding wireless
electronics such as cordless phones.
• Place the AP where there are minimum obstacles (such as walls and ceilings) between the AP and
the wireless client.
• Reduce the number of wireless clients connecting to the same AP simultaneously, or add additional
APs if necessary.
• Try closing some programs that use the Internet, especially peer-to-peer applications. If the wireless
client is sending or receiving a lot of information, it may have too many programs open that use the
Internet.
• Position the antennas for best reception. If the AP is placed on a table or floor, point the antennas
upwards. If the AP is placed at a high position, point the antennas downwards. Try pointing the
antennas in different directions and check which provides the strongest signal to the wireless clients.
EMG2881-T20A User’s Guide
111
APPENDIX A
Pop-up Windows, JavaScript and
Java Permissions
In order to use the web configurator you need to allow:
• Web browser pop-up windows from your device.
• JavaScript (enabled by default).
• Java permissions (enabled by default).
Note: The screens used below belong to Internet Explorer version 6, 7 and 8. Screens for other
Internet Explorer versions may vary.
Internet Explorer Pop-up Blockers
You may have to disable pop-up blocking to log into your device.
Either disable pop-up blocking (enabled by default in Windows XP SP (Service Pack) 2) or allow pop-up
blocking and create an exception for your device’s IP address.
Disable Pop-up Blockers
In Internet Explorer, select Tools, Pop-up Blocker and then select Turn Off Pop-up Blocker.
Figure 68 Pop-up Blocker
You can also check if pop-up blocking is disabled in the Pop-up Blocker section in the Privacy tab.
In Internet Explorer, select Tools, Internet Options, Privacy.
Clear the Block pop-ups check box in the Pop-up Blocker section of the screen. This disables any web
pop-up blockers you may have enabled.
EMG2881-T20A User’s Guide
112
Appendix A Pop-up Windows, JavaScript and Java Permissions
Figure 69 Internet Options: Privacy
Click Apply to save this setting.
Enable Pop-up Blockers with Exceptions
Alternatively, if you only want to allow pop-up windows from your device, see the following steps.
In Internet Explorer, select Tools, Internet Options and then the Privacy tab.
Select Settings…to open the Pop-up Blocker Settings screen.
EMG2881-T20A User’s Guide
113
Appendix A Pop-up Windows, JavaScript and Java Permissions
Figure 70 Internet Options: Privacy
Type the IP address of your device (the web page that you do not want to have blocked) with the prefix
“http://”. For example, http://192.168.167.1.
Click Add to move the IP address to the list of Allowed sites.
Figure 71 Pop-up Blocker Settings
EMG2881-T20A User’s Guide
114
Appendix A Pop-up Windows, JavaScript and Java Permissions
Click Close to return to the Privacy screen.
Click Apply to save this setting.
JavaScript
If pages of the web configurator do not display properly in Internet Explorer, check that JavaScript are
allowed.
In Internet Explorer, click Tools, Internet Options and then the Security tab.
Figure 72 Internet Options: Security
Click the Custom Level... button.
Scroll down to Scripting.
Under Active scripting make sure that Enable is selected (the default).
Under Scripting of Java applets make sure that Enable is selected (the default).
Click OK to close the window.
EMG2881-T20A User’s Guide
115
Appendix A Pop-up Windows, JavaScript and Java Permissions
Figure 73 Security Settings - Java Scripting
Java Permissions
From Internet Explorer, click Tools, Internet Options and then the Security tab.
Click the Custom Level... button.
Scroll down to Microsoft VM.
Under Java permissions make sure that a safety level is selected.
Click OK to close the window.
EMG2881-T20A User’s Guide
116
Appendix A Pop-up Windows, JavaScript and Java Permissions
Figure 74 Security Settings - Java
JAVA (Sun)
From Internet Explorer, click Tools, Internet Options and then the Advanced tab.
Make sure that Use Java 2 for
Source Exif Data:
File Type : PDF
File Type Extension : pdf
MIME Type : application/pdf
PDF Version : 1.6
Linearized : Yes
Encryption : Standard V2.3 (128-bit)
User Access : Print, Extract
Page Mode : UseOutlines
XMP Toolkit : Adobe XMP Core 4.0-c316 44.253921, Sun Oct 01 2006 17:14:39
Format : application/pdf
Creator :
Title :
Create Date : 2018:01:23 16:00:59+08:00
Creator Tool : FrameMaker 12.0.2
Modify Date : 2018:01:23 16:00:59+08:00
Metadata Date : 2018:01:23 16:00:59+08:00
Producer : Acrobat Distiller 11.0 (Windows)
Document ID : uuid:2fd79317-9df2-4812-94ea-edf9c5d968b7
Instance ID : uuid:05863537-56dc-47f4-adc6-84db86d20931
Has XFA : No
Page Count : 84
EXIF Metadata provided by EXIF.tools