One of our sites has 3 layers. many of our devices were down this morning. One of our engineers spotted the problematic the switch quickly. His words are attached. My question for you is how can you find this switch?
"That switch has gone wild. It was flooding the network with over 700mb of traffic and was bringing down all the switches except the two dsws. "
I doubt very much it was the switch itself , switches do not generate that kind of traffic flow on thier own , someone hung off that switch is a different story.
you should have a good knowledge of your network topology or at least trace using your network map. this would be an stp looping problem. you would want to issue show spanning-tree commands and find out which switch should not be in forwarding or blocking state. you could also check for the switch with high cpu by using show processes cpu and see which one has a high cpu utilization.