Detecting Loops

Detecting Loops
On switches that have a CPU usage indicator, this is sometimes also called “the spanning
tree loop indicator.” It’s relatively rare to see the CPU usage indicator get much past 20 percent
utilization for more than a few seconds at a time. If network connectivity has been lost
and you suspect a spanning tree loop is the culprit, take a look at the CPU usage indicator.
If utilization reaches 70 percent or higher, when the switch never sees that level of usage
during normal operation, that’s a good indicator of a spanning tree loop.