Research And Design Of The Skipnet-Based P2P-SIP Network System

With the rapid development of P2P and SIP Network in their respective area, more and more research organizations have started to do some research on how to combine the advantages of both P2P and SIP. P2P-SIP network system uses P2P technology to enable the function of SIP server which is a basic component in traditional SIP network. It can resolve the problems caused by the centralized structure of SIP network, such as single-point failure and performance bottleneck, by taking advantage of P2P.SkipNet network routing algorithm is firstly proposed to be used in P2P-SIP network system. In P2P-SIP network system, the algorithm of looking up P2P resources is utilized to locate SIP users. In reality, most sessions are initiated locally. SkipNet's locality properties guarantee that message traffic between two overlay nodes within the same domain is routed within that specific domain only. As a consequence, network load is decreased and the quality of communication can be improved. When locating SIP users, lookup is firstly implemented in the local domain. If the local lookup fails, search in the whole P2P network will be started. The purpose of this method is to decrease the probability of traffic through high-latency links, reduce the searching time cost at the same time, and accordingly reduce the average time for session establishing at last. Experiments show that implementing SkipNet routing algorithm in P2P-SIP system is an effective combination of both P2P and SIP's advantages.On the other hand, NAT is deployed in more and more networks because of the lack of IPv4 addresses, therefore, it is possible that some P2P-SIP nodes are behind NAT. P2P and SIP are both end-to-end services in Application Tier, so it is inevitable to solve the problem of NAT traversal in this SkipNet-based P2P-SIP network system. It is essential to implement the NAT traversal for SIP messages because all of the P2P-SIP nodes' information is exchanged by SIP messages. Several NAT traversal solutions for SIP are analyzed and finally a method which is suitable for this SkipNet-based P2P-SIP network system is proposed.