July 30, 2017
Tutorial: Cisco CCNA LAB
July 30, 2017
VLAN & VTP
VLAN stands for Virtual LANS (Local Area Network). These are implemented at switches to create a different group of users or different departments. VLAN ID is the user defined number given to the particular VLAN.
Trunking is used to pass data between two connected switches. The ports that connect the two switches at both the ends are made as trunk ports.
VTP (Virtual LAN Trunking Protocol). It is a switching technology and is used to replicate configurations and/or data between switches. It has three modes namely:
- Server Mode
- Transparent Mode
- Client mode
VTP has various uses, such as the four-floor concepts. The server room ( 4th floor) contains the server switch, operating in VTP server mode.
The 3rd floor consists of the transparent switch, connected to the server switch, operating in the VTP transparent mode.
The 2nd & the 1st-floor switches are the client switches, which are operating in the VTP client mode.
Switch1>enableSwitch1# conf tSwitch1(config)# interface fast 0/1Switch1(config-if)# switchport mode trunk (Making the port as trunk)Switch1(config-if)#ex Switch1(config)# vtp domain hpSwitch1(config)# vtp password 1234Switch1(config)# vtp mode server (optional : default mode is server) //Creating VLANSwitch1(config)# vlan 4Switch1(config-vlan)# name IT
Switch2>enableSwitch2# conf tSwitch2(config)# interface fast 0/1Switch2(config-if)# switchport mode trunk (Making the port as trunk)Switch2(config-if)#exSwitch2(config)# interface fast 0/2Switch2(config-if)# switchport mode trunk (Making the port as trunk)Switch2(config-if)#ex Switch2(config)# vtp mode transparent Switch2(config)# vtp domain hp Switch2(config)# vtp password 1234
Switch3>enableSwitch3# conf tSwitch3(config)# interface fast 0/1Switch3(config-if)# switchport mode trunk (Making the port as trunk)Switch3(config-if)#ex Switch3(config)# vtp mode client Switch3(config)# vtp domain hp Switch3(config)# vtp password 1234 Switch3# exitSwitch3# sh vlan brief (gives you the VLAN information)
:: In the output, you can see VLAN 10, It is created automatically. This is because data is replicated from switch 1 to switch 3, i.e; from the server to client.
Remember this happened because the VTP domain and password were the same for both server and client.
Note: The VLAN 10 will not be created in the switch 2 (transparent mode) because it only acts as a bridge between server and client.
Important troubleshooting commands:
· Show vlan brief
· Show vtp status
· Show interfaces trunk – view trunking info.
· Show vtp password
· Show ip interface brief – view brief information about the interfaces and the assign IPs.