I have three switches, first one is root bridge. To that one I have the two other switches connected via ethernet and a DSL line. Then I have a 4G modem connected to each MT device which each runs a EoIP tunnel in parallel back to root bridge switch. I set higher port path cost on each EoIP interface connected to the bridge in each MT device and setup works fine, EoIP over 4G is used when DSL fails but how can I control which which end get its ports forwarding and not forwarding? Right now the edge switches puts their EoIP interface in alternative role (not forwarding). I would rather make the root bridge switch put its EoIP ports in backup role (not forwarding) so broadcasts from root bridge switch does not need to be sent over 4G when path is not active. But I find no way how to do that, I cant get a port into backup role no matter what :( It is always the far side ports that get into their non forwarding role.
Best would be if both sides did not forward over EoIP/4G when not needed but RSTP might not be able to do that? Is it always just one side that is not forwarding?
Another thing about this behavior is that I can not easily tell from root bridge switch side which path is the active one :(