The Research And Design Of A New Generation Of P2PSIP System Based On DHT(Kad)

SIP is a Internet telephony signaling protocol proposed by IETF.The current SIP-based systems,most operated under C/S mode,have the problems of single point of failure and performance bottleneck.Because P2P networks have the merit of high scalability,robustness and self-organization,introducing the P2P techniques into SIP-based systems can improve the performance significantly and save equipment costs and management costs,this is why the P2PSIP system has been proposed.At an early stage,the research and design of P2PSIP system were based on the scheme of P2P over SIP,which establish P2P overlay network through the expansion of SIP.The latest draft of IETF P2PSIP Working Group rejected this scheme and determined to adopt the scheme of SIP over P2P,which means SIP running over P2P overlay and using the registration and location service provided by P2P overlay.After a thorough study of SIP protocol,distributed structured P2P network, Kademlia algorithm and the latest draft of IETF P2PSIP Working Group,the paper designs and implements a P2PSIP system based on DHT(Kad) algorithm,called PSBDK, using the SIP ove P2P scheme.The main research contents and work of this paper are listed as follows:Analyzes the entity structure and message mechanism of SIP protocol in detail, researches and compares the characteristics of a variety of P2P network topologies and focuses on the analysis of Kademlia algorithm based on DHT.After studying the latest draft of IETF P2PSIP Working Group,identifies the integration scheme of SIP over P2P,designs a P2PSIP system PSBDK based on DHT(Kad),designs the logic architecture of this system and provides a detailed analysis for each layer.Designs the modules and interactive messages of DHT(Kad) layer to realize the routing functionality and storage capability,whereby,SIP can carry out point-to-point communication;Designs the SIP layer and Media layer of PSBDK system.On the above-metioned basis,implements the prototype system and does functional testing and performance analysis.Offers PSBDK expansion analysis and resolution scheme from the aspects of NAT traversal,security and interoperability.