Why does nobody talk about spanning tree root bridge placement anymore?

I was helping a buddy fix a loop issue at his office in Denver last month, and the junior guy had the root bridge set on a random access switch in a closet. We spent 3 hours tracing why the whole network kept dropping every time someone rebooted that switch. Back in the day we always put it on the core or distribution layer and that was just common sense. Has anyone else seen this get overlooked in newer setups?

2 comments

2 Comments

benbrown29d ago

Piled right onto that one. I walked into a warehouse network once where the root bridge was a little 8 port desktop switch sitting on a shelf behind a filing cabinet. Somebody had set its priority to 0 years ago for a test and never changed it back. Every time the janitor unplugged it to vacuum the whole building's internet went down. We ended up putting the priority on a proper core switch and labeled the damn thing with a label maker so nobody could miss it again. Did you at least get that junior guy to run a show spanning-tree command before he makes changes now?

finleythomas29d ago

That junior guy probably learned from a YouTube video or a bootcamp that never mentioned root bridge election. So did he ever figure out why the random switch in the closet was winning the election? I'm curious if it was a lower MAC address or if someone manually set the priority to 0 and walked away. I've seen that happen more than once where someone changes a config without labeling anything and leaves a disaster for the next person. What did you end up setting the priority to after you fixed it?