IP Multicast (2)
multicast must be enabled on hosts and routers. If multicast is not supported, we have to built a tunnel i.e. encapsulate multicast messages in unicast datagrams
IGMP - Internet Group Membership Protocol (RFC 1112) used to dynamically register hosts in a multicast group with a class D address
IP multicast routing protocols (communication between routers):
- MOSPF - Multicast Open Shortest Path First (3Com) - multicast routing protocol; extension of OSPF; uses unicast routing protocol; MOSPF calculates routes from the source to all possible group members for a particular group; works only in inter-networks that use OSPF; optimized for small number of active sources