IGMP Snooping mcache Entries and Group Addresses

An IGMP snooping group address entry is created when an IGMP join message is received for a group. An IGMP snooping mcache entry is created when data traffic is received for that group. Each mcache entry represents one data stream, and multiple mcache entries (up to 32) can share the same hardware (MAC) address entry. The egress port list for the mcache entry is obtained from the IGMP group address entry. If there is no existing IGMP group address entry when an mcache entry is created, data traffic for that multicast group is dropped in hardware. If there is an existing IGMP group address entry when an mcache is created, data traffic for that multicast group is switched in hardware.