Understanding Nexus -- Part 13 -- VTP

Now we will have a look at how to configure VLAN Trunking Protocol (VTP) and VTP pruning on Cisco NX-OS devices.

Nexus supports VTP. But depends upon a NX-OS release like what kind of features it will support.

Beginning with Cisco NX-OS Release 5.1(1), VTP and VTP pruning are supported for VTP version 1 and 2.
Before Release 5.1(1), only VTP transparent mode was supported.

VTP info flows through Layer 2 trunk interfaces, Layer 2 trunk port channels, and virtual port channels (vPCs).

There is one more thing which you should keep in mind that, VLAN 1 is required on all trunk ports, if VTP is supported in the network. Disabling VLAN 1 from any of these ports prevents VTP from functioning properly.

All VTP packets received on the Nexus 7000 are dropped by default, if VTP is disabled. This is the default behavior on earlier NX-OS release versions. 
 

Enable VTP in transparent mode to extend a VTP domain through a Nexus. Once, enabled, VTP packets received on a trunk port are relayed to all other trunk ports. 
 

The NX-OS cannot be configured as a VTP client or server today (future feature after Release 5.1(1)).

Lets have a detailed look at VTP configuration parameters.

switch# config t
switch(config)# feature vtp
switch(config)# vtp domain accounting
switch(config)# vtp version 2         --- default is ver 1
switch(config)# vtp mode transparent  --- default server for ver 5.1
switch(config)# vtp file vtp.dat
switch(config)# vtp password cisco
switch(config)# vtp pruning           --- supported from 5.1
switch(config)# exit

Select the VTP domain name and version that match the values used in the existing VTP domain.

VTP Modes

Beginning with Release 5.1(1), VTP is supported in these modes.

Transparent — Mode that allows you to relay all VTP protocol packets that it receives on a trunk port to all other trunk ports
Server — Mode that allows you to create, remove, and modify VLANs over the entire network.  Beginning with Release 5.1(1), the server mode is the default mode. The VLAN information is stored on the bootflash and is not erased after a reboot.
Client — Mode that allows a switch to store the last known VTP information including the configuration revision number, on the bootflash.
Off — Mode that behaves similarly to the transparent mode but does not forward any VTP packets.

VTP allows you to enable or disable the VTP protocol on a per-port basis.