IGMP snooping

This provides a method for intelligently forwarding multicast packets within a Layer 2 broadcast domain. By “snooping” the IGMP (Internet Group Management Protocol) registration information, the device forms a distribution list that determines which endstations receive packets with a specific multicast address. Layer 2 switches listen for IGMP messages and build mapping tables and associated forwarding filters. IGMP snooping also reduces IGMP protocol traffic.