1 | IGMP (RFC 1112) - Internet Group Management Protocol - propagates multicast membership group information; this is used by multicast hosts to report their group membership to any immediately neighboring multicast routers; IGMP implements prunning algorithm in order to minimize traffic (paths to networks on which there are no subscribed recipients are pruned); |
2 | TTL - Time-To-Live limits the geographic range of a multicast session; ttl value is assigned to each packet for the session; ttl threshold is set in IP multicast-capable routers; ttl field in each packet is decremented as it hops from router to router; before the multicast packet hops over any mrouter its ttl value has to be greater than the mrouter's threshold value |