Research On Key Technologies Of VoIP Based On P2P-SIP

With the rapid development of network technologies, SIP-based VoIP systems have gotten more and more attention. It is a great challenge to the traditional telephone system. However, most existing VoIP systems use C/S structure, and the structure itself has inevitable problems: single point of failure and performance bottlenecks. P2P technology is a rising network technology. It can be used just to solve the existing deficiencies in VoIP systems for the characters of distribution, reliability and load balance.Now, the research on P2P-SIP technology is at the beginning, many problems have not been solved. In this paper, P2P-SIP networking technologies and P2P-SIP network security mechanisms have been studied. The main achievements are as follows:First of all, we do some research on the P2P-SIP networking technologies. We analyze and compare the routing algorithm of structured P2P networks, and then select the Chord with simple configuration good scalability as the underlying DHT structure of our P2P-SIP network in this paper.For the high dynamic characteristics of P2P-SIP network, a threshold signature based distributed authentication mechanism is proposed, which uses a dynamic threshold, when the number of nodes in the network changes, the participating nodes of the distributed authentication changes, too. This is a fully distributed process.Together with the distributed authentication mechanism, we also propose a malicious node detecting mechanism used in the P2P-SIP network. It realizes the real-time monitoring of the network nodes. Different NBS are defined in the P2P network against different kinds of attacks, so we can compare the messages sent by different nodes in P2P networks based on the NBS. A node is defined as a malicious node if the messages it sent are different with others. When the malicious node is found, a distributed authentication scheme is used to exclude the node out of the P2P networks.In this paper we also design a P2P-SIP based VoIP communication system that uses Chord as its underlying DHT structure. We realize the signaling transmission and session establishment. In the authentication module, we use the distributed authentication mechanism and malicious node detecting mechanism proposed in this paper, which improve the system's security.