aguilera
10-30-2007, 08:48 AM
Basic IGMP operation
Multicast router acts as both an IGMP host and an IGMP router in this and following descriptions, and as a result can respond to its own IGMP messages.
One router periodically broadcasts IGMP Query messages onto the link.
Hosts respond to the Query messages by sending IGMP Report messages indicating their group memberships.
All routers receive the Report messages and note the memberships of hosts on the link.
If a router doesn't receive a Report message for a particular group for a period of time, the router assumes there are no more members of the group on the link.All IGMP messages are raw IP datagrams, and are sent to multicast group addresses, with a TTL of 1. Since raw IP does not provide reliable transport, some messages are sent multiple times to aid reliability.
Multicast router acts as both an IGMP host and an IGMP router in this and following descriptions, and as a result can respond to its own IGMP messages.
One router periodically broadcasts IGMP Query messages onto the link.
Hosts respond to the Query messages by sending IGMP Report messages indicating their group memberships.
All routers receive the Report messages and note the memberships of hosts on the link.
If a router doesn't receive a Report message for a particular group for a period of time, the router assumes there are no more members of the group on the link.All IGMP messages are raw IP datagrams, and are sent to multicast group addresses, with a TTL of 1. Since raw IP does not provide reliable transport, some messages are sent multiple times to aid reliability.