The IGMP/MLD snooping feature provided for VPLS is supported similarly in the PBB I-VPLS context, to provide efficient multicast replication in the customer domain. The difference from regular VPLS is the handling of IGMP/MLD messages arriving from the B-VPLS side over a B-VPLS SAP or SDP.
The first IGMP/MLD join message received over the local B-VPLS adds all the B-VPLS SAP and SDP components into the related multicast table associated with the I-VPLS context. This is in line with the PBB model, where the B-VPLS infrastructure emulates a backbone LAN to which every I-VPLS is connected by one virtual link.
When the querier is connected to a remote I-VPLS instance, over the B-VPLS infrastructure, its location is identified by the B-VPLS SDP and SAP on which the query was received. It is also identified by the source B-MAC address used in the PBB header for the query message. This is the B-MAC associated with the B-VPLS instance on the remote PBB PE.
It is also possible to configure that a multicast router exists in a remote I-VPLS service. This can be achieved using the mrouter-dest command to specify the MAC name of the destination B-MAC to be used to reach the remote I-VPLS service. This command is available in the VPLS service PBB IGMP and MLD snooping contexts.
The following are not supported in a PBB I-VPLS context with IGMP snooping or MLD snooping:
multicast VPLS Registration (MVR)
multicast CAC
configuration under a default SAP
The following are not supported in a PBB I-VPLS context with MLD snooping:
configuration of the maximum number of multicast group sources allowed per group
configuration of the maximum number of multicast sources allowed per group