Configuring the VTP Version

Configuring the VTP Version
There are two versions of VTP that are configurable on Cisco switches. Version 1 is the default
VTP version on all switches and is typically used. No VTP version configuration is needed if you
will be running version 1. Version 1 and version 2 are not compatible, so it is an all-or-nothing
configuration for your switches. However, if all your switches are VTP version 2 compatible,
changing one switch changes all of them. Be careful if you are not sure whether all your switches
are version 2 compatible.

You would configure version 2 for the following reasons:
Token Ring VLAN support To run Token Ring, you must run version 2 of the VTP protocol.
This means that all switches must be capable of running version 2.
TLV support Unrecognized type-length-value (TLV) support. If a VTP advertisement is
received and has an unrecognized type-length-value, the version 2 VTP switches will still propagate
the changes through their trunk links.
Transparent mode Switches can run in transparent mode, which means that they only forward
messages and advertisements, not add them to their own database. In version 1, the switch
checks the domain name and version before forwarding, but in version 2, the switches forward
VTP messages without checking the version.
Consistency checks Consistency checks are run when an administrator enters new information
in the switches, either with the CLI or other management software. If information is received by
an advertisement or read from NVRAM, a consistency check is not run. A switch checks the digest
on a VTP message, and if it is correct, no consistency check is made.
To configure VTP version 2 on a 4000 series, use the set vtp v2 enable command:
Terry_4000> (enable) set vtp v2 enable
This command will enable the version 2 function
in the entire management domain.
All devices in the management domain should
be version2-capable before enabling.
Do you want to continue (y/n) [n]? y
VTP domain modified
Terry_4000> (enable)
The IOS-based switches once again demand that you access the VLAN database in order to
configure VTP. Both versions are supported, as shown next:
Terry_2950#vlan database
Terry_2950(vlan)#?
VLAN database editing buffer manipulation commands:
abort Exit mode without applying the changes
apply Apply current changes and bump revision number
exit Apply changes, bump revision number, and exit mode
no Negate a command or set its defaults
reset Abandon current changes and reread current database
show Show database information
vlan Add, delete, or modify values associated with a single VLAN
vtp Perform VTP administrative functions.
Terry_2950(vlan)#vtp ?
client Set the device to client mode.
472 Chapter 14  VLANs, Trunks, and VTP
domain Set the name of the VTP administrative domain.
password Set the password for the VTP administrative domain.
pruning Set the administrative domain to permit pruning.
server Set the device to server mode.
transparent Set the device to transparent mode.
v2-mode Set the administrative domain to V2 mode.