Configuring VLAN Trunking Protocol on Cisco Switch

VTP (VLAN Trunking Protocol)

VLAN Trunking protocol allows you to share information about VLAN configuration over the network switches. For example, if you have a VLAN on one switch in your network, the information needs to be distributed over different switches. The administrator has to configure VLAN on each switch separately. VTP allows you to add a new VLAN to the switch and propagate this information through the VTP messages to all other switches in layer 2 network causing them to add this new VLAN.  

   

Server Mode

Allows you to create, modify and delete VLANs and specify many configuration parameters. The VTP servers advertise their VLAN configuration to switches in the same VT P domain and synchronize their VLAN configuration with other switches based on advertisement received over trunk links. The server mode is the default mode for the VT P mode. A VT P server makes the changes and then sends a VTP messages regarding the changes on all of its trunks ports.

Transparent Mode

Forwards the VT P information to the network. This mode can add, modify and delete VLANs. The changes made only affect to that switch. A V TP transparent switch does not advertise its VLANs configuration and does not synchronize its VLAN based on the received advertisement that they receive out of their trunk ports.

Client Mode

Allows you to accept and store information from a VT P server to its RAM. The difference between a VTP server and a client is that you cannot create, modify or delete VLANs on a VTP client, the mode does not have permission to the VLAN configuration by itself. Whenever a client switch receives any VTP messages from a server switch, it incorporates the changes and then floods the VT P messages out of its remaining trunk ports. It always requires the assistance of the server switch to guide it about the VLAN configuration. The client switch gathers information from the server switch about the VLAN configuration every time its boots up. It does not store the VLAN configuration information in the NVRAM.

Functions performed by the VTP Modes

Server: - Add, Modify and Delete VLANs, Generate VTP messages, Propagate VTP Messages, Accept changes in VTP message, Default message.   

Transparent Mode: - Add, Modify and Delete VLANs, Propagate VTP Messages.

Client Mode: - Propagate VTP Messages, Accept changes in VTP message.

Configuration of VTP modes for three switch. 

We are creating two (Sales and Marketing) VLANs on switch 1 

Switch 1

VLAN 10 - fast Ethernet 0/1  

VLAN 20 - fast Ethernet 0/2

Fast Ethernet 0/10 uplink

Switch 2 

Fast Ethernet 0/10 uplink

Switch 2 

Fast Ethernet 0/11 uplink

Switch 3 

Fast Ethernet 0/10 uplink

Switch 1

Steps:

Creating VLANs

Switch1

Switch1>enable

Switch1#configure terminal

Switch1(config)#vlan 10

Switch1(config-vlan)#name sales

Switch1(config-vlan)#exit

Switch1(config)#vlan 20

Switch1(config-vlan)#name marketting

Switch1(config-vlan)#exit

VLAN Port Membership

Switch1(config)#interface fastEthernet 0/1

Switch1(config-if)#switchport access vlan 10

Switch1(config-if)#exit

Switch1(config)#interface fastEthernet 0/2

Switch1(config-if)#switchport access vlan 20

Switch1(config-if)#exit

Switch1(config)#

Setting up VTP server Mode 

Switch1(config)#vtp mode server 

Switch1(config)#vtp domain techxio.com

Changing VTP domain name from NULL to techxio.com

Enable Trunking on uplink  port  

Switch1(config)#

Switch1(config)#interface fastEthernet 0/10

Switch1(config-if)#switchport mode trunk

Switch1(config-if)#exit

Switch1(config)#vtp domain techxio.com

Switch1(config)#exit

Switch1#show vlan

Switch1#write

Switch 2

Switch2(config)#vtp mode client

Switch2(config)#vtp domain techxio.com

Switch2(config)#exit

Switch2#write

Switch2#show vlan

Switch2(config)#interface fastEthernet 0/10

Switch2(config-if)#switchport mode trunk

Switch2(config-if)#exit

Switch2(config)#exit

Switch2#write

Switch2#show vlan

Switch2(config)#interface fastEthernet 0/11

Switch2(config-if)#switchport mode trunk

Switch2(config-if)#exit

Switch2(config)#exit

Switch2#write

Switch2#show vlan

Switch 3

Switch3(config)#vtp mode transparent 

Switch3(config)#vtp domain techxio.com

Switch3(config)#exit

Switch3#write

Switch3#show vlan

Switch3(config)#interface fastEthernet 0/10

Switch3(config-if)#switchport mode trunk

Switch3(config-if)#exit

Switch3(config)#exit

Switch3#show vlan

Now All done, VTP mode has configured on both three switch. Now server switch will automatically share VLANs on both other Two clients switch.