Extreme Loop Recovery Protocol (ELRP) Port Shutdown

Extreme Loop Recovery Protocol (ELRP) detects loops by sending out an ELRP protocol data units (PDUs) out of one or more ports of a particular VLAN. ELRP takes system MAC addresses, changes them to a broadcast MAC address by appending “01:” to the front, and then sends out the PDUs. If PDUs are received back by ELRP, a loop is present. Each ELRP PDU is sent on a particular VLAN, so you must configure each VLAN that you wish to monitor.

In this ELRP enhancement, when a loop is detected using ELRP, an option to disable the port where the ELRP packet egresses is added to suppress the loop. You may specify a duration, which after it expires, the ports are enabled, or you can keep the ports disabled permanently until you choose to enable them.

Supported Platforms

  • BlackDiamond X8 and BlackDiamond 8800 series switches
  • Summit X770, X670, X670-G2, X480, X460, X460-G2, and X450-G2 series switches
  • E4G-200 and E4G-400 cell site routers


Entire port is blocked regardless of which VLAN that the loop was detected on.

Changed CLI Commands

The last six options in the following command were changed:

configure elrp-client periodic vlan_name ports [ports | all] interval sec [log | log-and-trap | trap] {disable-port {egress | ingress} {duration {seconds} | permanent }}

The output of the show elrp command now shows egress/ingress information in the “Action” column and there is a new column (Disable Port) showing disabled port status.

The output of the show elrp disabled-ports command now shows egress/ingress information in the new “Disable Direction” column.