I am studying for CCNP ENCOR and I could not get clear understanding how RSTP and MST can speak with each other. Specifically how it’s possible to make RSTP switch a root bridge.
So this is the scenario:
I have MST region with 3 switches and 1 Switch outside the region running RSTP.
My understanding how it works is this. (most likely wrong understanding)
To make RSTP switch a root bridge for entire spanning-tree topology I should make RSTP priority on all vlans less then any MST switch.
This is the lab I setup in EVE-NG
I have configured all switches with three vlans from 1 to 3.
I have only default IST region 0
I was unable to upload more than 1 screenshot so I cramped everything in 1 file. hope you can see everything
On SW1 I receive this log message:
%SPANTREE-2-PVSTSIM_FAIL: Blocking root port Gi0/1: Inconsitent inferior PVST BPDU received on VLAN 2, claiming root 2:5000.0006.0000
and port role that’s going to outside_sw is Root but BKN(broken?)
What I am missing, why this is happening? How BPDU can be inferior when it shows that root is outside_sw and priority is 1 and in the region all switches has higher (default) priority?