STP Root Guard Cause STP Topology Change ?

phucle001 · ‎07-16-2014

Hi Anyone,

Can anyone please advise if implementing Root Guard on the Root Bridge will cause a STP Topology Change, thus effectively causing a LAN outage because STP reconvergence is required?

I need to know this fact so I can decide to implement Root Guard during Business Hours or After Hours.

Thank you

Phuc

petenixon · ‎07-20-2014

It all depends on your topology and where you apply root guard. I think as long as you're only applying root guard to designated ports you will be ok.

If you apply root guard to a root port, where you would expect BPDUs, the port will stop forwarding.

Root bridge:
All (designated) ports configured for root guard.

STP switches:
All non-root (designated) ports configured for root guard.