ABSTRACT
Multiparty video conferencing differs from point-to-point communications in that there are more than two parties in real-time audio/video sessions, which changes the architecture of the system signifi cantly. In point-to-point real-time sessions, intermediary servers in the system for the delivery of audio and video streams are usually unnecessary. The only
servers needed are those that are used to discover other parties and establish real-time sessions. Once a real-time session is established, the delivery of audio and video streams is performed directly between the two communicating end points. In the case of multiparty video conferencing sessions, it is extremely diffi cult for individual participants to send and receive audio/video streams directly to, and from, all other participants. Therefore, intermediary servers are often used in meetings to route audio/video streams to all participants more effi ciently. It is also possible to organize participants in a session as a peer-topeer network, and to deliver audio/video streams without any dedicated server, as has been done by End System Multicast [1] and Skype. In any case, multiparty video conferencing sessions require some type of effi cient mechanism to route audio/video streams.
