STP bridge assurance port type change convergence

[Davideczech63]

Hello, 

I have couple of C93108TC-EX (7.0(3)I7(6)) running RSTP with globally enabled bridge assurance. They are connected via vPC to the ACI and have the uplinks configured as "spanning-tree port type network" so the BA is enabled here which is not actually what I want. 

What I want is to change the port type from network to normal (disable the BA on the uplink). Please can somebody advise, If this reconfiguration causes any disruption to the uplink? 

Thank you, 

[balaji.bandi]

yes it is, any STP configuration change have re-convergency, if topologies changes, So do it in maintenance window suggested all the time.

[paul driver]

Hello
Removing BA will no doubt cause a mismatch between switches on their interconnects especially when you change the stp port type a stp convergence would initiate, However would ports disable into a inconsistent state until that is you’ve removed it from both devices I have not tested it, but it seems logical.

Also if you have BA enabled that spans multiple interconnects then I would say those would be effected also

[Davideczech63]

Hello, 

Thank you for the answers. I guess simply put, we have three factors there: vPC and STP. If I change the STP port type for the member of vPC for sure It's Type 1 consistency paramater, so the secondary vPC member will be inconsistent, but I believe the primary should still forward frames.

Another factor is BA incosistency between neighboring switches. This is actually pretty interesting, because although the ports are shown as p2p the topology is the following: 

Since BA expects BPDUs and ACI just forwards everything inside of one EPG, I think that unless there are just two remaining bridges, the BA inconsistency shouldn't take place here?

The third factor is the change between network and normal type. I've tried to search some articles about what I can expect in terms of link availability, but haven't found any article. I assume, that If I will change the type, the port will go to discarding state by default, but not sure how long it will stay there in a loop free topology. 

Thanks, 

David