The IGMP proxy offers a mechanism for multicast forwarding based only on
IGMP membership information. The router must decide about forwarding
packets on each of its interfaces based on the IGMP membership
information. The proxy creates the forwarding entries based on the
membership information and adds it to the multicast forwarding cache
(MFC) in order not to make the forwarding decision for subsequent multicast
packets with same combination of source and group.
What Is MLD?
Multicast Listener Discovery (MLD) protocol enables IPv6 routers to
discover the presence of multicast listeners, the hosts that wish to receive the
multicast data packets, on its directly-attached interfaces. The protocol
specifically discovers which multicast addresses are of interest to its
neighboring nodes and provides this information to the active multicast
routing protocol that makes decisions on the flow of multicast data packets.
The Multicast router sends General Queries periodically to request multicast
address listeners information from systems on an attached network. These
queries are used to build and refresh the multicast address listener state on
attached networks. Multicast listeners respond to these queries by reporting
their multicast addresses listener state and their desired set of sources with
Current-State Multicast address Records in the MLD2 Membership Reports.
The Multicast router also processes unsolicited Filter-Mode-Change records
and Source-List-Change Records from systems that want to indicate interest
in receiving or not receiving traffic from particular sources.
The PowerConnect implementation of MLD v2 supports the multicast router
portion of the protocol (i.e., not the listener portion). It is backward-
compatible with MLD v1.
Managing IPv4 and IPv6 Multicast