Wednesday, March 26, 2008

VTP Version

When configuring VTP, be carrefull to use the CORRECT VTP Version... You can check it using the command show vtp status it´ll show you the Supported Version (VTP Version) and the Configured Version (VTP V2 Mode).

If the VTP V2 Mode field = Enable than you´re running VTP Version 2.

Or... if the field VTP V2 Mode = Disable, you´re running VTP Version 1 mode.

Once again, do not confuse the VTP Version and the VTP V2 Mode fields, the first shows you which VTP Mode your switch is capable, and the second which VTP Version is actually configured.

See the example bellow:

switch#sh vtp status
VTP Version                     : 2
Configuration Revision          : 175
Maximum VLANs supported locally : 1005
Number of existing VLANs        : 71
VTP Operating Mode              : Client
VTP Domain Name                 : lab-02
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Enabled
VTP Traps Generation            : Disabled
MD5 digest                      : 0x42 0x9F 0x9A 0xF2 0x61 0x74 0x0A 0xAC
Configuration last modified by at 1-25-08 22:34:22


It´s always good to "CLEAR" the VTP Configuration Revision number of your Switch before adding a new switch to the network.

The easist way to do that is to change the VTP Domain Name -vtp domain <new domain name> (example: vtp domain lab01) in the switch configuration, and then, changing it back to the original one. That will clear your configuration revision number. DO NOT FORGET to change the switch back to the desirable VTP Domain Name, and use the correct password if needed to have it working properly!

Also... set the switch mode to client - vtp mode client before attaching it to the network, so it learns "all" the VLANs from other operational switch, and then, if needed just change it to server - vtp mode server .

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