@AngryTransLady @hacks4pancakes Also do not intermingle PVST and RSTP in the same production network. Worst-case I've seen was a regional trauma center (hospital) sending all emergent patients out-of-country [1] thanks to those competing protocols not coexisting nicely.

Of course I've also flatlined a network for 6+ hrs while trying to fix it preventitively(?), so YMMV :-/

[1] only about two miles away across the border, but still a Really Big Problem. No-one died or had any resulting permanent major problems as a result, that I know of.