CCNA RSE Lab: 6.2.3.9 Troubleshooting VLAN Configurations

CCNA RSE Lab: 6.2.3.9 Troubleshooting VLAN Configurations

Topology
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Addressing Table

Device Interface IP Address Subnet Mask Default Gateway
S1 VLAN 1 192.168.1.2 255.255.255.0 N/A
S2 VLAN 1 192.168.1.3 255.255.255.0 N/A
PC-A NIC 192.168.1 0.2 255.255.255.0 192.168.10.1
PC-B NIC 192.168.10.3 255.255.255.0 192.168.10.1
PC-C NIC 192.168.20.3 255.255.255.0 192.168.20.1

Switch Port Assignment Specifications

Ports Assignment Network
F0/1 802.1 Q Trunk N/A
F0/6-12 VLAN 10 – Students 192.168.10.0/24
F0/13-18 VLAN 20 – Faculty 192.168.20.0/24
F0/19-24 VLAN 30 – Guest 192.168.30.0/24

Objectives
Part 1: Build the Network and Configure Basic Device Settings
Part 2: Troubleshoot VLAN 10
Part 3: Troubleshoot VLAN 20

Background / Scenario
VLANs provide logical segmentation within an internetwork and improve network performance by separating large broadcast domains into smaller ones. By separating hosts into different networks, VLANs can be used to control which hosts can communicate. In this lab, a school has decided to implement VLANs in order to separate traffic from different end users. The school is using 802.1Q trunking to facilitate VLAN communication between switches.

The S1 and S2 switches have been configured with VLAN and trunking information. Several errors in the configuration have resulted in connectivity issues. You have been asked to troubleshoot and correct the configuration errors and document your work.

Note: The switches used with this lab are Cisco Catalyst 2960s with Cisco IOS Release 1 5.0(2) (lanbasek9 image). Other switches and Cisco IOS versions can be used. Depending on the model and Cisco IOS version, the commands available and output produced might vary from what is shown in the labs.

Note: Make sure that the switches have been erased and have no startup configurations. If you are unsure, contact your  instructor.

Instructor Note: Refer to the Instructor Lab Manual for the procedures to initialize and reload devices.

Required Resources

  • 2 Switches (Cisco 2960 with Cisco IOS Release 15.0(2) lanbasek9 image or comparable)
  • 3 PCs (Windows 7, Vista, or XP with terminal emulation program, such as Tera Term)
  • Console cables to configure the Cisco IOS devices via the console ports
  • Ethernet cables as shown in the topology
Part 1: Build the Network and Configure Basic Device Settings

In Part 1, you will set up the network topology and configure the switches with some basic settings, such as passwords and IP addresses. Preset VLAN-related configurations, which contain errors, are provided for you for the initial switch configurations. You will also configure the IP settings for the PCs in the topology.

Step 1: Cable the network as shown in the topology.
Step 2: Configure PC hosts.
Step 3: Initialize and reload the switches as necessary.
Step 4: Configure basic settings for each switch.

a. Disable DNS lookup.
b. Configure the IP address according to the Addressing Table.
c. Assign cisco as the console and vty passwords and enable login for console and vty lines.
d. Assign class as the privileged EXEC password.
e. Configure logging synchronous to prevent console messages from interrupting command entry.

Step 5: Load switch configurations.
The configurations for the switches S1 and S2 are provided for you. There are errors within these configurations, and it is your job to determine the incorrect configurations and correct them.
Switch S1 Configuration:

Switch S2 Configuration:

Step 6: Copy the running configuration to the startup configuration.

Part 2: Troubleshoot VLAN 10

In Part 2, you must examine VLAN 10 on S1 and S2 to determine if it is configured correctly. You will
troubleshoot the scenario until connectivity is established.

Step 1: Troubleshoot VLAN 10 on S1 .
a. Can PC-A ping PC-B? ______________ No
b. After verifying that PC-A was configured correctly, examine the S1 switch to find possible configuration errors by viewing a summary of the VLAN information. Enter the show vlan brief command.
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c. Are there any problems with the VLAN configuration?
Yes. The port for PC-A is not assigned to the correct VLAN. The port for F0/1 is assigned to VLAN 1 ; therefore, it is not acting as a trunk port.

d. Examine the switch for trunk configurations using the show interfaces trunk and the show interfaces f0/1 switchport commands.

e. Are there any problems with the trunking configuration?
Yes. No trunk ports exist and F0/1 is configured as an access port instead of a trunk port.

f. Examine the running configuration of the switch to find possible configuration errors.

Are there any problems with the current configuration?
Yes. F0/1 -5 are all configured as access ports and all ports on the switch are shutdown.

g. Correct the errors found regarding F0/1 and VLAN 10 on S1 . Record the commands used in the space below.

h. Verify the commands had the desired effects by issuing the appropriate show commands.

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i. Can PC-A ping PC-B? ______________ No

Step 2: Troubleshoot VLAN 10 on S2.
a. Using the previous commands, examine the S2 switch to find possible configuration errors.

Are there any problems with the current configuration?
Yes. No ports were assigned access to VLAN 10 and ports F0/1 and F0/11 are shutdown.
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b. Correct the errors found regarding interfaces and VLAN 10 on S2. Record the commands below.

c. Can PC-A ping PC-B? ______________ Yes

Part 3: Troubleshoot VLAN 20

In Part 3, you must examine VLAN 20 on S1 and S2 to determine if it is configured correctly. To verify functionality, you will reassign PC-A into VLAN 20, and then troubleshoot the scenario until connectivity is established.

Step 1: Assign PC-A to VLAN 20.
a. On PC-A, change the IP address to 192.168.20.2/24 with a default gateway of 192.168.20.1.
b. On S1, assign the port for PC-A to VLAN 20. Write the commands needed to complete the configuration.

c. Verify that the port for PC-A has been assigned to VLAN 20.
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d. Can PC-A ping PC-C? ______________ No

Step 2: Troubleshoot VLAN 20 on S1 .
a. Using the previous commands, examine the S1 switch to find possible configuration errors.

Are there any problems with the current configuration?
Yes. VLAN 2 was created instead of VLAN 20 and ports have been assigned to VLAN 2 instead of VLAN 20.

b. Correct the errors found regarding VLAN 20.

c. Can PC-A ping PC-C? ______________ No

Step 3: Troubleshoot VLAN 20 on S2.

a. Using the previous commands, examine the S2 switch to find possible configuration errors.

Are there any problems with the current configuration?
Yes. The trunked interface has been misconfigured to allow communication for VLAN 2 instead of VLAN 20 and port f0/18 is shutdown.
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b. Correct the errors found regarding VLAN 20. Record the commands used below.

c. Can PC-A ping PC-C? ______________ Yes

Note: It may be necessary to disable the PC firewall to ping between PCs.

Reflection
1. Why is a correctly configured trunk port critical in a multi-VLAN environment?
An 802.1Q trunk port allows for transmission of multiple VLANs across one link. An incorrectly configured trunk port can prevent VLANs from communicating across switches.

2. Why would a network administrator limit traffic for specific VLANs on a trunk port?
To prevent unwanted VLAN traffic from traveling through that trunk port.

Device Configs

Instructor Note: The VLANs configured do not display in the running configuration but are stored in the vlan.dat file.

Switch S1

Switch S2

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