VTP

[aslam mohammad]

Hi Geeks,

I have a little confusion on vtp revision number

If i add a new switch with highest Revision number into network what will happen.

      1  New switch with highest revision number  as a server mode.

      2  New switch with highest revision number  as a client mode.

Thanks

[cwhite0013]

Hello,

With VTP version 1 / 2, a client or a server could overwrite your VLAN database. If you add a new switch that is in VTP client mode with a higher revision number than your existing VTP server, the existing VTP server will overwrite it's VLAN database with the VLAN database from the client.

For example, if you have two switches, switch A and switch B. Switch A is a VTP server and Switch B is a new switch in client mode with a higher revision number. When we connect Switch A to Switch B, Switch B will start sending out summary advertisements even though it's in client mode. When Switch A receives these advertisements, it will see that Switch B has a higher revision number and request Switch B's VLAN information. Switch B will send over the VLAN information (even though it's a client) and Switch A will overwrite it's VLAN database with Switch B's information. 

This is a big reason why VTP version 1 / 2 aren't used in production networks any longer. In networks that do use VTP, they use VTPv3 which has additional security measures to protect against taking down a network. 

[paul driver]

Hello

Just like to add, When ever you add a switch to a production Lan, make sure the vtp mode is set to transparent, or the very least change it to transparent and then to client before you attach it to the network.

This will reset the switch revision number to 0 and thus will not be able to advertise a higher revision value.

Shouldn't have any issue with new switch's unless your network has a very low revision number active on the network, or you are running vtp 3, But to be safe I would preform this proceed anyway.

res
Paul