VTP how to disable the VLAN trunking protocol

Initially, a switch will have the following default parameters for VTP:

• VTP operating mode: Server
• VTP Domain Name: Null

In such a case, VTP is active, but switches will not actively create any VTP associations with any other switches simply because the domain has not been configured. When all switches have a domain of NULL, it is as if VTP is not functioning.

However, this can still be a dangerous situation, because if a rogue switch is added which has a VTP domain configured, it will start to send VTP messages, and any switch on the network that still has a NULL domain, will automatically adopt that domain as well.

You can't disable VTP as a feature, but you can ensure that a switch never participates in any VTP domain that may appear on the network by simply changing the VTP mode to transparent like so:

Switch(config)#vtp mode transparent

This ensures that any VTP messages received will be ignored.

VTP version 3 has a couple of additional options:

One is to disable VTP on a per interface basis. The other is to disable VTP completely using the vtp mode off command. This command essentially is the same as the transparent mode, but the switch doesn’t forward VTP messages.

Links:

https://networklessons.com/switching/introduction-to-vtp-vlan-trunking-protocol

https://forum.networklessons.com/t/introduction-to-vtp-vlan-trunking-protocol/870/164?u=lagapides