How to trace the STP loop in a campus network with over 250 switches

you are in a predicament. easiest way would have been to use a network diagram based on a stead-state environment.

how do you know you have a STP loop? Are you receiving log messages? Post them if you can. that will be a good start to figure out how to isolate your loop.

if you don't have a diagram or can't figure out where the loop is, you need to identify where the redundant links are. systematically disable redundant links and see if the network stabilizes.

show spanning-tree summary show spanning-tree show spanning-tree root

The STP loop problems are not because of the redundant links at the core or the distribution. But it is more likely that incorrectly configured wireless accesspoints are creating a loop between them. And being bpdu packets are not recieved back by the connected switch port, it wasn't blocked and causing the loop. It took a while to figure out those incorrectly configured wireless accesspoints are causing the loop. What are the best options and spanning-tree commands to put in the switch ports' config to prevent such loops happening again if someone incorrectly configure the APs again?