VTP Recovery

Unanswered Question
Jun 12th, 2007

Hi Guy's

I know that if we insert a switch with high VTP revision number in the network it may wipe out the existing vtp information.In this case how can we bring back all the information and the network to stable without much delay.



I have this problem too.
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Erick Bergquist Tue, 06/12/2007 - 22:13

Be very careful when adding the new switch so the info doesn't get over written and write down your vlan info just in case. Before plugging it in, default the vtp revision on new switch or if it is not a core switch maybe set vtp mode to transparent.

Maybe even make a few small non-network effecting changes to the vtp server so it's revision number is increased higher than that of the new switch your adding.

Remember, even a switch in vtp client mode can wipe out vtp info in the network if it's revision number is highest.

I don't know of a way to recover VTP info, other then manually configuring vlan info across the network again. Unless, you have some switch with the info still you can make into a vtp server and maybe get the info repropagted before it gets zapped itself.

Keep in mind, some switches keep a seperate vlan database so restoring a old running config from backup may not recover the vlan info.

HTH, Erick

royalblues Tue, 06/12/2007 - 22:40

The only way i think is to quickly recreate all the vlans.

when the vlan gets actually deleted all the ports would be in a suspended state and should resume again once the vlan is back.

Better to always backup the VLAN.DAT file.

HTh, rate if it does


guruprasadr Tue, 06/12/2007 - 23:06

HI, [Pls Rate if Helps]

Always take Backup of VLAN.DAT file in the VTP Server & restore in such situations.

Then, there is a time required for the VTP Server to advertise its domain, password info & other details to the VTP Clients.

Atlast, Sync of Server & Client for Back to Normal Operation.

Note: VTP Information will not be saved in the Running / Start-up configuration. Only VLAN.DAT file can help you in such situation.

If you don't have the Backup of VLAN.DAT file then you need to quickly recreate all the VLANS in Server & CLient Switches.

Pls Rate if Helps

Best Regards,

Guru Prasad R

mahmoodmkl Wed, 06/13/2007 - 00:34


Thanks for the reply.

How can we do it on catos,i think catos doesnt has vlan.dat file.


Jon Marshall Wed, 06/13/2007 - 01:13

Hi Mahmood

You are correct, the vlan.dat file does not exist in CatOS as it is not needed because CatOS automatically commits everything to NVRAM whenever a config change has been made.

You just need to take a full copy of the running config on CatOS as all the commands to recreate the vlans and allocate the correct ports into the correct vlans are contained within the config.



glen.grant Wed, 06/13/2007 - 04:19

Use a vtp password if possible on your network and "always" default the any switch that needs to be configured and reinstalled on the network and verify the vtp revision number sits at 0 before installing . We haven't tried it but it may be possible to back up the vlan.dat file for the servers .


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