Disabling PVST simulation on an MST>RSTP link

Hello

Two situations are possible on a link between an MST region and a non-MST region:

• either the root for all vlans is in the MST region OR
• the root for all vlans is in the non-MST region

To meet the condition, BPDU for vlans other than 1 needs to be identical or better than BPDU for vlan 1. This means e.g:

priority for vlan 1 = 8192 + system-id (1)

priority for all other vlans = 4096 + system-id (2 or higher).
This is called PVST simulation. We can disable it on the port with the command:

spanning-tree mst simulate pvst disable.

After enabling this, the port between the MST region and non-MST region will be blocked.