Impact of changing mst 0 priority

[ccnak1ing]

We had a change on the mst 0 priority and subsequently had vrf's failover to the redundant device, however the vrf's failed back within minutes. Now none of these vrf's vlans are in mst 0 so i am a bit baffled that they were impacted.

Can anyone explain how or why the priority change should cause an impact, I've looked through cisco for documentation to support this but haven't foun anything so far

Thanks

[Mohamed Sobair]

Hi,

Instance 0 (MST 0) the IST is especial instance  that is used to carry the BPDUs to the IEEE address, however , The MST by definition , each instance has its own topology view and Spanning-tree calculation. This shouldnt impact other MST instances, basically it shouldnt happen.

You might have other reason for vrf svlan instance to fall back, you might check if you have some other changes/incidents took place in the Network.

Regards,

Mohamed