VTP ( VLAN Trunking Protocol) - 802.1Q

VTP ( VLAN Trunking Protocol) - 802.1Q

VLAN Trunking Protocol (VTP) is a Cisco Layer 2 messaging protocol that manages the addition, deletion, and renaming of VLANs on a network-wide basis. Virtual Local Area Network (VLAN) Trunk Protocol (VTP) reduces administration in a switched network. When you configure a new VLAN on one VTP server, the VLAN is distributed through all switches in the domain. This reduces the need to configure the same VLAN everywhere. VTP is a Cisco-proprietary protocol that is available on most of the Cisco Catalyst Family products.

VTP has 3 operational modes as follows

1. Server ( default )

2. Client

3. Transparent 

How it's operating ?

As usual all the Cisco switches are on VTP server mode by default. that means such switched works as a server to manage VLANs. When we configure VLANs on switch in server mode and connects it to the network, it sends advertisement to the other switches on the network in every 5 minute which contain details about VLANs where configured on him self. 

The network can be contain other switched in client mode and transparent mode. When a Vlan advertisement  received by a client switch, it automatically make configurations of vlan on him self according to the advertisement and pass it to the next switch.

When a advertisement received by a transparent switch, it only pass it to the next and no make any configurations on him self. 

Configurations can be done as follows.

Server mode - can configure VLANs on switch, Send advertisements, Don't receive updates

Client mode - can't configure VLANs on switch, don't send advertisements, receive updates

Transparent mode - can configure VLANs on switch, Pass through advertisements