1900 Series Switch
2900 Series Switch
2950 Series Switch
VTP versions 1 and 2 are not interoperable. All switches must use the same version. The biggest difference between version 1 and 2 is that version 2 has support for Token Ring VLANs.
Switches that are in client mode update their VLAN database from switches that are in server mode. If you have two or more switches interconnected and you delete a VLAN database, you may find that it becomes updated from a server switch because of your VTP mode.
Another serious problem occurs when you take a new switch in server mode (the default mode) and plug it into an existing network. If the VTP revision number is higher on the new switch, it sends an update to all other switches to overwrite their VLAN database with new informationin this case, an empty VLAN database. You now have a production network with no VLAN information.
Recommended practice is that you put a switch into VTP client mode before adding them into a production network, allow it to receive an update of current VLAN information, and then change it to VTP server mode.