STP - Dispute
STP Dispute is a feature of Spanning Tree Protocol (STP) that checks if the BPDUs that it receives on an interface match with the port role/state of the interface. This helps to detect unidirectional link failures and prevent bridging loops. When a designated port detects a problem, it will keep the port role but changes its state so that all traffic is dropped until the issue is fixed. Dropping all traffic isn’t ideal, but it’s better than the alternative, which is a bridging loop.
This mechanism is supported in the PVST+, RSTP, and MST modes, but not in standard 802.1D STP.