Configure the VTP domain and implement a unified configuration and management of VLANs

The working principle of VTP

VTP: Virtual LAN Relay Protocol, VTP is a message protocol that uses a second frame to pass VLAN information between switches, known as VTP notifications. With the VTP notice, you can change the VLAN configuration centrally on one switch, and the modifications will be automatically propagated to the other switches on the network to achieve a consistent VLAN configuration.

VTP domain

The VTP domain, also known as the VLAN admin domain, consists of more than one switch that shares VTP domain names. That is, the VTP domain is a group of switches that have the same VTP domain name and are connected to each other via a relay link. Using VTP you first need to establish a VTP admin domain where the switches in the same admin domain share their VLAN information, and a switch can only participate in one VTP admin domain.

The requirements for configuring the VTP domain are as follows:

1, each switch in the domain must use the same VTP domain name.

2, the switch must be adjacent, that is, adjacent to the switch and have the same domain name.

3, the switch must be configured before the relay link (that is, trunk).

The pattern of VTP

1. Server mode: The switch that acts as the VTP server mode is responsible for the management of VLAN information in its domain. The VTP server can create, delete, or modify VLANs, and send out VTP notices, while VTP servers learn the same VTP notification information for domain names.

2. Client mode: A switch in VTP client mode does not allow administrative creation, deletion or modification of VLANs. They listen for VTP notifications from other switches in this domain and modify their own VTP configurations accordingly.

3, Transparent mode: VTP transparent mode of the switch does not participate in VTP. When the switch is in transparent mode, it can create, delete, or modify local VLAN information, but it does not advertise its VLAN configuration information, forwarding only the VTP notifications received and not learning and changing its VLAN information.

VTP Notice

When using VTP, each switch that joins the VTP domain notices the following information on the relay port:

1, admin domain (that is, VTP domain name information)

2, version number (using VTP version number, as long as the server and client mode to verify that the version is consistent)

3, Configuration modification number (default is 0, after modifying the configuration of the VTP domain, this number will add 1)

4, the VLAN it knows (that is, all VLANs in VTP)

5, some of the parameters of each VLAN (VLAN related information)

Note: When a switch joining this VTP domain with a modified number that is higher than the change number in this VTP domain, the VLAN configuration in this switch overrides the VLAN configuration in all VTP domains, so be careful when adding the switch to the VTP domain. We can change the switch's VTP mode to transparent mode, change back to server mode or switch mode, or change the domain name of the switch back to the switch, and the change number can be changed to 0.

VTP Trim

VTP pruning is a feature of VTP that reduces unnecessary broadcast traffic on the relay link.

Configuring VTP instances

Before configuring VTP, we need to set the link between the VTP server and the VTP client as a relay link.

Columns such as: Set the SWITCH1 and Switch's port 24th to trunk Relay link.

Switch1 (config) #int f0/24

Switch1 (config) #switchport mode trunk

Switch1 (config) #no sh

Switch2 (config) #int f0/24

Switch2 (config) #switchport mode trunk

Switch2 (config) #no sh