Prior to ExtremeXOS 15.3.2, you could configure static groups, but it was necessary to specify port(s). As of 15.3.2, the configuration of dynamic groups is now supported. The MLD 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 MLD 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. When you configure a group on a VLAN but do not specify the port, the switch forms an MLDv1 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 mld snooping {vlan} vlan_name {ports portlist} add [static | dynamic] group ip_address