IGMP Snooping Interfaces and Forwarding

IGMP snooping divides the device interfaces into multicast-router interfaces and host-side interfaces. A multicast-router interface is an interface in the direction of a multicasting router. An interface on the bridge is considered a multicast-router interface if it meets at least one of the following criteria:

• It is statically configured as a multicast-router interface in the bridge instance.
• IGMP queries are being received on the interface.

All other interfaces that are not multicast-router interfaces are considered host-side interfaces.

Any multicast traffic received on a bridge interface with IGMP snooping configured will be forwarded according to following rules:

• Any IGMP packet is sent to the Routing Engine for snooping processing.
• Other multicast traffic with destination address 224.0.0/24 is flooded onto all other interfaces of the bridge.
• Other multicast traffic is sent to all the multicast-router interfaces but only to those host-side interfaces that have hosts interested in receiving that multicast group.