StackPort is Topology Change Initiator?

cisco_trooper

This is a Catalyst 3750 Stack configured with StackWise. I have a device on the Stack somewhere that continues to cause RSTP convergence, but the stack master only reports that the topology change initiator is StackPort2. I should be able to trace this back to the end device without much problem, but the output on this stack is indicating StackPort2. Has anyone else come across this? Is there a better command to use?

I'd prefer to be able to get this information without re-enabling the logging event link-status on all the end user devices and without sniffing traffic.

#show spanning-tree detail | inc rstp|occur|from
 VLAN0888 is executing the rstp compatible Spanning Tree protocol
  Number of topology changes 168 last change occurred 00:00:55 ago
          from StackPort2

vinbuck

I don't know of a better command to use...you can try a debug span event and see if it lists the port, otherwise you'll be wiresharking for a tcn flag

cisco_trooper

Yeah, I obviously don't know of a better command either, but I'm not arrogant enough to think I know of everything.

I ended up turning the logging back on for the link-status events. I waited for RSTP to converge again and then checked for the link that changed states. I don't understand WHY Cisco is providing the source of the convergence as StackPort2. The TCN was caused by an edge device that had portfast disabled. Configuration error from my network admin.

Thanks vinbuck.