Supporting multimedia conferencing with implicit multicast

IP multicast is not suitable to support multimedia conferencing for several important reasons, particularly its routing scheme, method of addressing and lack of group management. Building on the results of the implicit multicast (IMcast) routing protocol, we describe a network architecture for the present day Internet to support multimedia conferencing. IMcast enables us to use a multicast address space separate from that of unicast. Instead of a flat class D address, the IMcast multicast address has a hierarchical structure to identify multicast subnets, conferences and streams. We introduce a new class of network elements called multicast information servers (MIS) to effect group management such as address allocation, group discovery, connection set up and reconfiguration using SIP or HTTP. A working prototype of the service model exists