STP - Root Inconsistency State

When implementing Spanning Tree Protocol (STP), the root guard feature helps prevent a port from incorrectly becoming a root port by putting a port in the Root Inconsistency state in the event that it receives a superior BDPU. In this state, superior BPDUs will not be accepted.

A port will remain in the root inconsistency state as long as superior BPDUs are being received. Once the superior BPDUs stop, the port will automatically go back to its operational state.

You could attempt to bring it back by shutting down the port and bringing it back up again, but if superior BPDUs are still being received, it will go into the inconsistency state again.

The proper procedure is to simply resolve the superior BPDU issue, and the root inconsistency state will resolve itself.

Links

https://forum.networklessons.com/t/spanning-tree-rootguard/1144/55?u=lagapidis

https://networklessons.com/spanning-tree/spanning-tree-rootguard