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Topology change in one VLAN of an MSTP instance affects all VLANs in that instance?


I have a question regarding MSTP.


Say I have 3 switches, A B and C.  A and B are connected to each other using a trunk link and A is the STP root.  Then, I connect switch C to switch B using an access port which is on vlan 100.  And, switch C's priority is lower than both A and B for VLAN 100.


I believe that if all these switches are running R-PVST, the behavior is that C will cause B to perform an RSTP sync-proposal-agreement but only for vlan 100.  This will cause a momentary outage for ONLY vlan 100 between A and B.  All other VLANs will not be affected.


Let me know if I got it right for MSTP.  In MSTP, since all VLANs are in a single instance, a change to one instance affects all the VLANs of that instance.  There will be a momentary outage for all VLANs between A and B.  Is that right?


Thank you in advance!




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