Based On The Design Of The P2p-sip Ip Phone System With Some

The development of Internet extends the using of VoIP, which is taking place of PSTN step by step. In the current IP Telephone system based on C/S architecture,all users have to register to central server before making any phone call, so the ability of central server is a bottle-neck of the whole system. P2P overlay makes better use of client node, which improves the loading ability and stability of whole system. As core protocol of VoIP, SIP has already been trying to transfer C/S to P2P.P2P-SIP draft, which is proposed by IETF, declares a P2P architecture based on chord algorithm. This architecture can improve the routing performance to O( log N) hops per routing request. P2P-SIP uses REDIRECT model to make sip request closer to the target node on every hop. However, it can not be widely used in practical, as it does not work well in a NAT circumstance. A P2P-SIP solution based on CAN architecture, which effectively solves the NAT transportation,is designed and implemented。The contribution of this dissertation mainly includes:1. SIP protocol is deeply analyzed, and several P2P architectures are discussed.2. A P2P-SIP protocol based on CAN is proposed. Comparing with the P2P-SIP base on chord, the cost of joining and leaving the system is much more smaller, futhermore, the routing performance is imporved to O( N ).3. A practical method to penetrate NAT is designed and implemented, and the arriving probability of SIP protocol is improved.4. A IP Telephone system based on P2P-SIP is implemented, and the test methods and results are given.