The guard-timer command sets the Guard timer of an ERPS ring.
The undo guard-timer command restores the default value of the Guard timer.
By default, the Guard timer is 200 centiseconds for the ERPS ring.
Usage Scenario
After a faulty link or node recovers, the nodes on the two ends of the link or the faulty node sends ring auto protection switching (R-APS) protocol data units (PDUs) to inform the other nodes of the link or node recovery and starts a Guard timer. Before the timer expires, each involved node does not receive any R-APS PDU to avoid receiving out-of-date R-APS PDUs indicating that the link or node fails. If the involved node receives an RAPS packet indicating that another port fails, the local port enters the Forwarding state.
Precautions
If the value of the Guard timer is set too small, network loops will occur. The default value is recommended.