Replacing VTP server switch

[Andy White]

Hello,

I'm due to replace a stack of 2 x 3750 switches very soon with 2 x 3750Gs.  These 2 current switches are the VTP server for a small domain.  I have put the config on the new switches switches and I made it a server and used the same VTP domain and password etc and got the VLAN info ported over.

Now I did this a while back and noticed the switches are in transparent mode with a revision number of 0, I need to set this back to server and swap the switches out but the revision will be lower than the client switches (around rev 200), what do I need to do?

Thanks

[glen.grant]

  Check your clientt switches , if all the vlan info is correct   then the new server will just import the vlan data off the clients as the clients will have a higher revision number.   Take a snapshot of what the vlans are before doing this just in case something does happen.  Other wise you would have to make vlan changes  on the new server switch 201 times to get the revision number  higher than the clients.  Not sure what would happen if you say imported the vlan.dat file off  a client switch. Have never tried it in a lab .  Maybe someone else can chime in if they have a better idea.  If it's not a big environment with a lot of vlans you might consider making all the switches transparent.

[Andy White]

What if I add the new stack as a client and as a trunk to the one of the switches the domain, as it's revision number is 0 will it not get the new revision number from the server of clients and retain the current vlan info (vlan.dat)?

[glen.grant]

  If it has the same domain name and password , it will get it's vtp updated even if it's only a client . It all depends on the revision number, so if  even a "client" has a higher revision number and you attach a server ,the server will get it's info from that client with the higher revision. 

[paul driver]

Hello

I would recommend to before adding a new switch or stack

• If an existing vtp server/client exists make sure it has all the live vlans already in its database
  

or

• On the existing switch stack- prior to changing it to vtp server mode and if the revision number isnt that high create some vlans one by one, you can delete them later) this will increment this revision number other than 0)
  
  If there is a switch out on the network with a very high revison number then as long as it as all the vlans in its database as stated above ( the existing stack will obtain the revision number of a higher server/client and you will be good, from here you can either leave the exisitng stack as the vtp server and" demote" the others server/clients and leave them all as is.
  

• Once the new switches have been configured with the correct vtp domain/password (if applicable) and before adding them to the existing network change to vtp mode to transparent and back to client
  

res

Paul

Please don't forget to rate any posts that have been helpful.

Thanks.

[Andy White]

Thanks, I made it a VTP client and then add it as a trunk and it got the revision number, I then removed the trunk and made it a vtp server.

VTP can be scary, but as long as the the revision number is lower than the active server when adding I'm ok.

[paul driver]

Hello Andy

Dont want to scare you but I forgot to do this once on a automotive manufacturing site and wipe the whole vtp estate !

res

Paul

Please don't forget to rate any posts that have been helpful.

Thanks.

[Andy White]

Yeah I've read some horror stories and my CCNP is going on about it too.  I tend to always get a new switch and set it to transparent to set the revision to zero (used switches I also delete the vlan.dat & config etc).

I originally added the new switch stack as a client to obtain all the VLAN info then configured the rest of the switch and set it to transparent and took it off the network for a few weeks (due to scheduling downtime).  Today I added it back onto the VTP domain as a client and it got the latest revision number and kept all the VLAN info.  I have now taken it off again and set the VTP mode to server as I will be powering down the current stack of server switches later this week to put these in.

Hope that made sense

Fingers crossed.