Research And Design Of SIP Communication System Based On Hierarchical Peer-to-peer Structure

Compare with the traditional C/S model SIP communication systems, combining VoIP with Peer-to-peer technology is definitely a new attempt. In this paper, by using peer-to-peer advantages of decentralize and load balancing, we can overcome the the single point of failure, performance bottleneck and other issues in SIP communnication.In peer-to-peer model, resource location is a core issue. This paper chooses Chord ring, a structred peer-to-peer architecture, as the resource organization model. Chord model has the advantages of better scalabiltiy and fewer jumps. However, the heterogeneity of nodes and their location informantion have not been taken into account, which result in longer lookup latencies and more physical hops. At the same time, the integration of peer-to-peer and SIP has brought new security risks, both from SIP own and inherited security threat from p2p structure. At this point, Security problems in the system should also be considered. Aimed at the two points, the work we have done as followed:1. Present hierarchical p2p architecture suitable for SIP users' location.This paper presents a hierarchical structured p2p location model. Group the nodes into different subnets according to their physical proximity such as IP addresses. A peer using SIP message embedded P2P message searches for user in a specific sub-net. Only when it fails then redirects the search request to super-node to relocate user, reducing the possibility of passing by higher latency link as much as possible.2. P2P extension to SIPIn the P2P-SIP system, the resource location and communication are accomplished by using SIP message. Through the extension to SIP message, the system can complete node joining, user registration, location and session establishment.3. Security research on P2P-SIPThis paper uses petri net to model and analyse P2P-SIP and particularly brings forward a solution to Bye message attacks. From the operating results of the model, we can see that the model is according with the practical application of the system. Although the modeling analysis is based on P2P-SIP system, for the C/S model SIP security also have some reference.