Consistency support for a decentralized management in close multiparty conferences using SIP

Distributed multimedia applications such as conference and collaborative applications require an appropriate conference management. Close group conferences like meetings, discussions, tele seminars, or consultations need a strictly controlled group membership. Current conference systems achieve this by using a centralized group server as specified in the H.32x standards. Decentralized approaches are scarcely used so far, although they are more flexible. They avoid infrastructure dependencies and single point of failure problems which are often encountered in group server approaches, e.g. in classical virtual private networks. A decentralized conference management requires a consistency support by the underlying communication service. The session initiation protocol (SIP) has become a widely applied protocol to support the signaling of multimedia applications in the Internet It is also applied to support multiparty conference applications. The great majority of these approaches is related to open group and centralized organized conferences. For closed decentralized managed conferences, no solutions have been proposed up to now. In this paper we present such a group communication service based on SIP that ensures the consistency of decentralized managed group data.