IGMP Loopback

Prior to ExtremeXOS 15.3.2, you could configure static groups, but it was necessary to specify port(s). As of ExtremeXOS Release 15.3.2, the configuration of dynamic groups is supported. The IGMP Loopback feature, along with the existing static group feature, supports the configuration of static and/or dynamic groups with or without ports.

A VLAN in loopback mode may not have ports associated with it, but its operational status is up. However, it is not possible to have multicast receivers on a VLAN without having a port. Sometimes there is a need to pull the multicast traffic from upstream to the loopback VLAN for troubleshooting. The traffic need not always be forwarded to any ports/receivers. The IGMP Loopback feature allows you to configure groups on a VLAN without specifying a port, so the traffic is pulled from upstream but not forwarded to any port.

The loopback (Lpbk) port is the logical port on a VLAN in the application context. If you configure a group on a VLAN but do not specify the port, the switch forms an IGMPv2 join and assumes it to be received on the Lpbk port. A dynamic group ages out after the membership timeout if there are no other receivers. Membership joins refresh the dynamic group. The static group remains until it is removed from the configuration.

The following command is used to configure static or dynamic group entry :

configure igmp snooping {vlan} vlan_name {ports port_list} add [static | dynamic] group ip_address