VLAN trunking protocol
(also VLAN trunk protocol, VTP)
VLAN trunking protocol definition
A VLAN trunking protocol (VTP) is a Cisco proprietary protocol. With a VLAN trunking protocol, you can also synchronize VLAN information, like VLAN ID or VLAN name. It decreases administration in a switched network because it reduces the need to configure the same VLAN on all the switches on your network. So, without a VLAN trunking protocol, you’d have to manually enter VLAN configuration commands on each switch on your network, which takes a lot of time.
VLAN trunking protocol modes
- Server mode. Server mode is the default VLAN trunking protocol mode. A catalyst switch working in server mode can create, modify, and delete VLANs for the entire VLAN trunking domain. VLAN configurations are saved in the catalyst’s nonvolatile random-access memory.
- Client mode. If a VLAN trunking protocol is operating in client mode, it cannot create, change, or delete VLANs on the VLAN trunking domain. It can send VLAN trunking protocol messages, but it does not save VLAN configurations in nonvolatile memory.
- Transparent mode. While in transparent mode, a switch can forward the VLAN trunking protocol advertisements they have received from other switches that belong to the same management domain. Transparent mode allows switches to create, delete, and modify VLANs. However, those changes are not transmitted to other switches in the same domain. Instead, they only affect the local switch.