Spanning Tree Protocol

[Bob Oneil]

Do all of the HP switches in a network need to be on the same firmware to enable STP? I have a new 2920 that I am adding to a group of older 2900's. Should I expect any issues when i turn on STP?

Thanks

Bob

[Pete W]

Bob,

Q : Do all of the HP switches in a network need to be on the same firmware to enable STP?

A : No. However it helps if all the switches are speaking the same "flavour" of STP. By default all fairly modern HP ProVision switches speak MSTP when STP is enabled.

Q : Should I expect any issues when i turn on STP?

A : It depends ...

If you have simply enabled STP on the 2900s and nothing else then you may not know where your "Root Bridge" [RB] is. If the new 2920 switch starts producing STP BPDUs with a lower MAC address than the existing RB, then the network will reconverge around the new switch.

Best practice is to select a central location for your RB, and manually set the stp priority to 0 at that location. This will/may cause a reconvergence, so do it at an appropriate time. At that point adding further switches to the network should not cause the network to reconverge.

Regards,

Peter