Method for managing multicast addresses for transmitting and receiving multimedia conferencing information on an internet protocol (IP) network implemented over an ATM network

In a multicast capable IP network (102) implemented over an ATM network, each client terminal on a multimedia conference, for each media type it transmits, is assigned a multicast IP address and a port number (together known as a socket) on which to transmit packets, wherein each assigned multicast IP address is unique and different than the multicast IP address assigned to any other client for any media type. Each client terminal then selects, for each media type, which clients on the conference it wants to receive packets from. Only packets that are in fact requested by a client are routed over the multicast IP network to the requesting client. A single special purpose Multicast Address Resolution System (MARS) server is associated with the conference when the conference is established. Each client terminal uses that MARS server, whether on the same or different IP sub-networks, but on a common ATM network, for purposes of mapping the multicast IP addresses used in the conference into a set of unicast ATM endpoint addresses used by the ATM-connected client terminals. Similarly, when a specific conference uses a Multicast Server, a single special purpose Multicast Server is used for all clients on the conference, whether on the same or different IP sub-networks, for purposes of establishing point-to-multipoint ATM connections to the conference endpoints.