VLAN Trunking Protocol

Fig 1: VLAN Trunking Protocol

VTP is the layer 2 protocol means the data link layer protocol. VTP is the cisco proprietary protocol and this protocol is the protocol that work is to carries the information of the VLAN to all the switches in the domain of VTP. VTP is protocol which is used to create, delete, and modify VLANs and then that propagates to the other switches in the domain of the VTP. So VTP advertisement can be done on the basis of the ISL trunks and 802.1Q.

VTP Prerequisite

Trunk is the prerequisite of the VTP.
VTP domain name should same on all switches.
There should be at least one server in the VTP domain.
If you enable the authentication than it should match.

VTP Modes

There are the three modes of the VTP that play different role in the VTP domain:

Server
Client
Transparent

Server

Server is the mode of the VTP which is used for the creation of the VLAN and this mode is also used for the deletion and the modification of the VLANs. If you create, delete, and modify any VLAN than it propagate to all the switches in the VTP domain. In this mode the configurations are all save in the start-up configuration that is also known as the non volatile random access memory (NVRAM).

Client

Client is the mode of the VTP which is not able for the creation of the VLAN and also not for the deletion and the modification of the VLANs. Clients mode's work is only propagate the configuration to other switches.

Transparent

Transparent is the third mode of the VTP which is also used for the creation of the VLAN and this mode is also used for the deletion and the modification of the VLANs. So the roles of server and transparent are same but there is a big difference that is this mode does not participate in the VTP domain and because of this attitude of the transparent mode it used for the acquiring the privacy and security.

Modes	Create VLAN	Delete VLAN	Modify VLAN
Server	√	√	√
Client	x	x	x
Transparent	√	√	√