Research And Design Of A New Type Of P2P-SIP Internet Telephony Based On DHT

With the constant development of network technology, the network communication has involved traditional voice business. Internet-telephony, as one of the new service in Internet, not only has a lot of advantages just like cost cheap and high network resource utilization ratio, but also can realize the interactive real-time communication through further integrating multimedia information (voice, image, data). Internet-telephony has very big development potential; it has already gradually substituted for the tradition PSTN telephony, and has been the main form of voice information transmission in NGN. Recently, Internet-telephony based SIP or H.323 often uses the Client/Server mode. Although the C/S mode is simple, it has many limitations. The servers in this mode are expensive and hard to maintain or upgrade, and they will obviously become the bottleneck of the system.As a new network technology, Peer-to-Peer (P2P) technology has developed quickly. The majority of P2P network does not need centralized servers, and it will not be affected for the single node failing. The P2P network has a lot of advantages, just like: self-organizing, scalability, fault-tolerance, etc. Combined the P2P technology with SIP protocol, the advantage of both has been fully exploited. The new type of Internet-telephony system model which does not need centralized servers has been designed,and whereas it has solved the problems due to the failure in centralized directory server in SIP Internet-telephony, making the management easy and reducing the system charge.The thesis focuses on the new Internet-telephony system which combines the advantages of P2P and SIP. It analyses SIP protocol and DHT (CHORD) algorithm. Then it extends the SIP protocol, introducing the DHT-based fully distributed P2P architecture into the traditional SIP Internet-telephony, designing a new type of telephone system. The thesis makes a thorough research and discuss on the relative techniques on the prototype system design.The research results could act as the references for developing the similar products that combine P2P architecture with SIP standards, and also gives out a new thought for VoIP technique developing under fully distributed P2P network environment.