Method and system for a unicast endpoint client to access a multicast internet protocol (IP) session

Unicast endpoint clients on an IP Unicast network are provided access to Multicast sessions on an IP Multicast network through a Multicast-Unicast gateway server. The server obtains information about sessions on the Multicast network and makes such information available to a Unicast client on the Unicast network upon request by the client. Upon being presented with a list describing the subject matter of each session, the user at the Unicast client selects the session to which he or she wants to join, which causes the Multicast-Unicast server to join the appropriate session on behalf of the requesting client. All packets then received by the server from the Unicast client are address-translated to the appropriate Multicast session address and vice versa. The Unicast client is then able to participate in the Multicast session as both a sender and receiver of packets to and from other Unicast and Multicast clients which are active.