Remember – VTP is sent untagged (so ends up on the native VLAN)

Posted on 2010/12/14 by RedNectar Chris Welsh

When VTP sends updates, they are sent without tags. So (assuming the native VLAN is VLAN 1) if you have restricted your trunk port at the receiving end with a command like:

switchport trunk allowed vlan 2,10,20

it will drop all untagged traffic – including the VTP updates.
Solution

switchport trunk allowed vlan add 1
Posted in Cisco, VTP | 1 Comment