As usual, H200 ignores. Nobody on subnet 3 expressed interest in listening to this multicast session, so R1 does not forward these packets to R3, nor does R2. First of all we need a new part of the address space for multicast group addresses. To Live selectable by the user, or always 1. - Where a choice of subents exists to multicast over, just select one. If the IP packet specifies a Host Group, brodcast it.
Routers identify themselves by sending a HostMembershipQuery.
The router is informed of Host Group membership by receipt of a HostMembershipReport from at least one host on a subnetwork. The router need only receive one of these Reports to maintain the multicast association for that address. Two good ways to reduce flooding with unnecessary multicast packets. Any router which receives a packet addressed to AllHosts will not forward it over any other link. H2 is a multicast sender which is happily broadcasting away on subnet 2 Breezeway Cam, let's say.