IGMPv2

This feature introduces support for IGMP (Internet Group Management Protocol) version 2 (IGMPv2). IGMPv2 adds an explicit leave message to the join message so that routing devices can more easily determine when a group has no interested listeners on a LAN. IGMP manages the membership of hosts and routers in multicast groups. IP hosts use IGMP to report their multicast group memberships to any immediately neighboring multicast routers. Multicast routers use IGMP to learn, for each of their attached physical networks, which groups have members.