Using ELRP with ESRP

Extreme Loop Recovery Protocol (ELRP) is a feature of ExtremeXOS software that allows you to prevent, detect, and recover from Layer 2 loops in the network.

You can use ELRP with other protocols, including ESRP.


When used on a VPLS service VLAN, ELRP does not detect loops involving the VPLS pseudowires.

For more information about standalone ELRP, see Using ELRP to Perform Loop Tests.

With ELRP, each switch, except for the sender, treats the ELRP protocol data unit (PDU) as a Layer 2 multicast packet. The sender uses the source and destination MAC addresses to identify the packet it sends and receives. When the sender receives its original packet back, that triggers loop detection and prevention. After a loop is detected, the loop recovery agent is notified of the event and takes the necessary actions to recover from the loop. ELRP operates only on the sending switch; therefore, ELRP operates transparently across the network.

How a loop recovers is dependent upon the protocol that uses the loop detection services provided by ELRP.

If you are using ELRP in an ESRP environment, ESRP may recover by transitioning the ESRP domain from master to slave. The following sections describe how ESRP uses ELRP to recover from a loop and the switch behavior: