Troubleshooting VTP

Determine what is not currently working

Step 1: confirm switch names, interface connections, and vtp modes
Step 2: identify the sets of two neighboring switches that should be either vtp clients or servers whos vlan database differs with the show vlan command
Step 3: On each pair of connected switches who differ in database configuration verifty: at least one operational trunk, vtp domain name match or mismatch, and vtp password match or miss match
Commands to use: show interface trunk, show interface switchport, or show cdp neighbors, show vtp status, show vtp password.
Step 4: if any mismatches exist reconfigure the switches so that the vtp information matches

Troubleshooting VTP LAB

Step One.) Use show cdp neighbors, show interfaces trunk, show VTP status and show interfaces switchport to gather the hostname, interface connections and vtp modes.

Host Name: SW1 { show cdp neighbors }
Interface Connections: SW2 via Fas 0/1, SW3 via Fas 0/2 { show cdp neighbors }
VTP Mode: Sever { show vtp status }

Host Name: SW2
Interface Connections: SW1 via Fas 0/1,  SW3 via Fas 0/48
VTP Mode: Client

Host Name: SW3
Interface Connections: SW1 via Fas 0/2, SW2 via 0/24
VTP Mode:  Client

Step Two.) Identify the neighboring switches that vlan databases differ with the show vlan command.

SW1 differs from SW3

Step Three.) Verify that a trunk exists, the vtp domain matches, and the vtp password matches.

a.) Use the show interface trunk command to confirm a trunk exists between the two switches. ( mine did not )

b.) Since a trunk did not exist between sw1 and sw3 I used show cdp neighbor to find out which port sw3 was connected to on sw1. Once I determiend that it was fastethernet 0/2 I went in and checked the port mode sure enough trunking was not enabled. Below are the commands I used to resolve the issue.

SW1#show cdp neigbhors ( found out it was fastethernet 0/2 I need to look at)
SW1#show interface fastethernet 0/2 (found out trunking was not enabled)
SW1#configure terminal
SW1(config)#interface fastethernet 0/2
SW1(config-if)#switchport mode trunk
SW1#show interfaces trunk (trunk to SW3 came online.

c.) Next I used show vtp status to confirm the password and domain were correct

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