An Application Layer Extension for Multipoint Communication for the Session Initiation Protocol

The session initiation protocol (SIP) enables multipoint communications through the use of conferencing and IP multicast, but the usefulness of SIP's multiparty communications is limited. This paper introduces an extension to SIP that provides membership awareness, fault tolerance, and partition recovery for conferencing. The extension also supports application layer multicast for session negotiation and transfer of necessary session information for protocol initialization. We report performance results that characterize message size, message processing time, and partition reformation delays. Using a ring protocol implementation, we demonstrate the ability of the extension to operate with an application layer multipoint protocol and evaluate performance with respect to message size and reformation delay.