IGMP and MLD Snooping Switches

A snooping switch can be configured to receive IGMP (Internet Group Management Protocol) packets in a subnet and identify ports on which interested IP multicast listeners are present. It also identifies the ports on which multicast routers are attached, and these are the likely ports on which IP multicast sources are present. This section describes how the snooping switch handles IGMP messages, addresses considerations for IGMP packet and IP multicast traffic forwarding, and provides information about support for IGMP and MLD versions.