I understand how to manipulate the FP root and secondary-root for the two MD trees, but how are the 'blocked' links selected? And how can I manipulate them? :)
I tried doing this with metric tuning, but it didn't appear to work - my switch prefers the higher-cost path to the root. I wondered if it chose the highest system-id or switch-id, along the lines of root selection, but my tree in-lab is favoring a switch with lower IDs for each. I even wondered if it couldn't be manipulated live, but a shut/no-shut didn't help.
Or maybe I'm just wrong about my root-selection. Is there a command to verify root status?