VLAN Trunking Protocol (VTP) is used to sync name settings and to prune VLANs from the trunk links that are destined for Layer 2 devices that do not have any ports active in that respective VLAN. The user can also specify a VTP domain name for identifying it easily. It requires you to enable trunking, through which the VTP domain name would get popularized, even to the switch on which the domain name is not configured. VTPs with the different domain name will not exchange any information.

Some features of VTP are as follows:

• VTP sends information to maintain VLANs on trunked switches to accelerate the trunking
• It is a Cisco proprietary protocol for managing VLANs and runs on any type of trunk mechanism
• VTP is functioned in common VTP domain between switches
• VTP passwords can be set to control the exchange of information
• VLAN 2 to VLAN 1002 are managed by VTP
• VTP allows switches to exchange their updates based on the revision number
• There are three different modes of VTP to operate
• VTP can prune unwanted VLANs from trunk links

By default, no VTP passwords are set, so any switch with trunk enabled port can join the domain or any switch with the same VTP domain name can join it and capture the traffic, so to secure this VTP password is set. And the information is exchanged after the successful authorization:

Three different modes are assigned to VTP-enabled switches. They are server (default mode), client, and transparent, respectively. Hence the switch can be configured in any of these VTP modes to function:

• Server: This is the default mode of VTP. In VTP server mode, we can create, modify, and delete VLANs. We can also configure other parameters such VTP password, version, or pruning for the entire domain. These servers share their VLAN information and sync with other switch's databases based on the updates received on their trunk links.
• Transparent: These switches do not participate in the domain. They neither update their database nor do they advertise any information with the other switches. The only function that they perform in the case of VTPv2, is to pass on the update received on their port to the next switch in the domain.
• Client: They also operate in a similar manner with that of the server, but the only difference is that they cannot create, modify, or delete any VLANs like the server VTPs can do.