6.1.2.7 Packet Tracer Investigating A VLAN Implementation Instructions

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Packet Tracer – Investigating a VLAN Implementation

Topology

Addressing Table

Device

Interface

IP Address

Subnet Mask

Default Gateway

S1

VLAN 99

172.17.99.31

255.255.255.0

N/A

S2

VLAN 99

172.17.99.32

255.255.255.0

N/A

S3

VLAN 99

172.17.99.33

255.255.255.0

N/A

PC1

NIC

172.17.10.21

255.255.255.0

172.17.10.1

PC2

NIC

172.17.20.22

255.255.255.0

172.17.20.1

PC3

NIC

172.17.30.23

255.255.255.0

172.17.30.1

PC4

NIC

172.17.10.24

255.255.255.0

172.17.10.1

PC5

NIC

172.17.20.25

255.255.255.0

172.17.20.1

PC6

NIC

172.17.30.26

255.255.255.0

172.17.30.1

PC7

NIC

172.17.10.27

255.255.255.0

172.17.10.1

PC8

NIC

172.17.20.28

255.255.255.0

172.17.20.1

PC9

NIC

172.17.30.29

255.255.255.0

172.17.30.1

Packet Tracer – Investigating a VLAN Implementation

© 2013 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public. Page 2 of 4

Objectives

Part 1: Observe Broadcast Traffic in a VLAN Implementation

Part 2: Observe Broadcast Traffic without VLANs

Part 3: Complete Reflection Questions

Background

In this activity, you will observe how broadcast traffic is forwarded by the switches when VLANs are configured

and when VLANs are not configured.

Part 1: Observe Broadcast Traffic in a VLAN Implementation

Step 1: Ping from PC1 to PC6.

a. Wait for all the link lights to turn to green. To accelerate this process, click Fast Forward Time located in

the bottom yellow tool bar.

b. Click the Simulation tab and use the Add Simple PDU tool. Click on PC1, and then click on PC6.

c. Click the Capture/Forward button to step through the process. Observe the ARP requests as they

traverse the network. When the Buffer Full window appears, click the View Previous Events button.

d. Were the pings successful? Why?

e. Look at the Simulation Panel, where did S3 send the packet after receiving it?

In normal operation, when a switch receives a broadcast frame on one of its ports, it forwards the frame out

all other ports. Notice that S2 only sends the ARP request out Fa0/1 to S1. Also notice that S3 only sends the

ARP request out F0/11 to PC4. PC1 and PC4 both belong to VLAN 10. PC6 belongs to VLAN 30. Because

broadcast traffic is contained within the VLAN, PC6 never receives the ARP request from PC1. Because PC4

is not the destination, it discards the ARP request. The ping from PC1 fails because PC1 never receives an

ARP reply.

Step 2: Ping from PC1 to PC4.

a. Click the New button under the Scenario 0 dropdown tab. Now click on the Add Simple PDU icon on the

right side of Packet Tracer and ping from PC1 to PC4.

b. Click the Capture/Forward button to step through the process. Observe the ARP requests as they

traverse the network. When the Buffer Full window appears, click the View Previous Events button.

c. Were the pings successful? Why?

d. Examine the Simulation Panel. When the packet reached S1, why does it also forward the packet to

PC7?

No, because pc1 and pc6 in different vlans and there is no trunk

on pc4

yes, because pc1 and pc in the same VLAN

because pc7 in the same vlan that pc1

Packet Tracer – Investigating a VLAN Implementation

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Part 2: Observe Broadcast Traffic without VLANs

Step 1: Clear the configurations on all three switches and delete the VLAN database.

a. Return to Realtime mode.

b. Delete the startup configuration on all 3 switches. What command is used to delete the startup

configuration of the switches?

c. Where is the VLAN file stored in the switches?

d. Delete the VLAN file on all 3 switches. What command deletes the VLAN file stored in the switches?

Step 2: Reload the switches.

Use the reload command in privileged EXEC mode to reset all the switches. Wait for the entire link to turn

green. To accelerate this process, click Fast Forward Time located in the bottom yellow tool bar.

Step 3: Click Capture/Forward to send ARP requests and pings.

a. After the switches reload and the link lights return to green, the network is ready to forward your ARP and

ping traffic.

b. Select Scenario 0 from the drop down tab to return to Scenario 0.

c. From Simulation mode, click the Capture/Forward button to step through the process. Notice that the

switches now forward the ARP requests out all ports, except the port on which the ARP request was

received. This default action of switches is why VLANs can improve network performance. Broadcast

traffic is contained within each VLAN. When the Buffer Full window appears, click the View Previous

Events button.

Part 3: Complete Reflection Questions

1. If a PC in VLAN 10 sends a broadcast message, which devices receive it?

2. If a PC in VLAN 20 sends a broadcast message, which devices receive it?

3. If a PC in VLAN 30 sends a broadcast message, which devices receive it?

4. What happens to a frame sent from a PC in VLAN 10 to a PC in VLAN 30?

5. In terms of ports, what are the collision domains on the switch?

6. In terms of ports, what are the broadcast domains on the switch?

erase startap-config

flash:vlan.dat

delete vlan.dat

every in vlan 10

every in vlan 20

every in vlan 30

drop

each port is a collision domain

numbers of vlans

Packet Tracer – Investigating a VLAN Implementation

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Suggested Scoring Rubric

Activity Section

Question

Location

Possible

Points

Earned

Points

Part 1: Observe Broadcast

Traffic in a VLAN

Implementation

Step 1d

6

Step 1e

5

Step 2c

6

Step 2d

5

Part 1 Total

22

Part 2: Observe Broadcast

Traffic without VLANs

Step 1b

6

Step 1c

6

Step 1d

6

Part 2 Total

18

Part 3: Complete

Reflection Questions

1

10

2

10

3

10

4

10

5

10

6

10

Part 3 Total

60

Total Score

100