STP working on core switches

[yadhukrishna]

Hi, I have two core Nexus 9K switches on which one is acting as a root bridge and obviously other is not. So what if i want to move the root bridge? Also i am planning on a switch upgrade on which is not a root bridge. Will that impact any services as the traffic is routed via the root bridge

[marce1000 · Accepted solution]

 - Traffic is not routed trough a root bridge, it only deals with spannimg tree. You need to change the bridge priority or priorities for that matter tp point to the designated root bridge ,

 M.

[Joseph W. Doherty · Accepted solution]

"So what if i want to move the root bridge?"

You move it.

If you're wondering can it impact your network operations, it certainly can!

Basically, that root bridge's L2 domain, should block until it resolves the new loop free topology based on the new root.

How long that will actually take depends on multiple factors, and it can run over a minute.

"Also i am planning on a switch upgrade on which is not a root bridge. Will that impact any services as the traffic is routed via the root bridge"

Insufficient information to say.

Can say, usually less impactful then dropping the root bridge, but actual impact depends on multiple factors, including how you drop it out of the network.

[Samsoum]

-Set the root bridge priority on your Core switch to ZERO value.

-You can make a Back-up switch by changing the root bridge priority to 4096.

-Leave the other switch in default priority of 32768 value.

-Remember always all configuration of RSTP must be done RING open.

By this you force the core switch to be the RSTP root.

[Giuseppe Larosa · Accepted solution]

Hello @yadhukrishna ,

if the two Nexus 9000 core switches form a vPC pair you should consider the use of the feature under vpc domain

peer-switch

you will need to configure the same STP bridge priority on both devices but from external device point of view they will see only one device acting as the root bridge  ( one of the two chassis sends BPDUs like they were sent from the active chassis and received BPDUs are sent to the active chassis).

This is likely the best move if they are a vPC pair.

Hope to help

Giuseppe