Implement Of Topology-aware P2P Relay Search Mechanism In SIP Terminal

SIP is the main application-layer control protocol in the field of multimedia communication. Because the SIP communication system is based on C / S architecture, almost all of the media stream between the various users need the SIP server to route. Therefore, it is prone to appear performance bottleneck. The architecture of the P2P network is distributed, it has many advantages such as high scalability, robustness and high fault tolerance etc. All the nodes in the P2P system are equal communication entities. If combining the SIP system and P2P system, it can not only avoid the performance bottleneck, but also improve the SIP network architecture. Finally, it can promote the quality of the media exchange.Besides, as the best-effort service of the Internet, the VoIP system existed QoS problem. In order to improve QoS, most systems used application-layer routing mechanism. One of the key issues of the mechanism was how to search relay node. Once the optimal relay node was found, then the two endpoints can make use of it to relay their media streams.Based on the analysis of SIP + P2P prototype system, unilateral optimal relay search program was proposed. In this scenario, the source terminal selected a relay node from its cache. Such that the route quality between the source node and the selected node is the best. Then a communication link between the source node and the dest node which through the selected node was established. The way of relay search in the prototype system was unilateral, which made the relay node was only optimal to the source node, rather than to the both sides.In order to improve this scheme, an application-layer routing scheme called topology-aware P2P relay search mechanism was proposed. First, in order to simulate the real Internet topology, a Cluster Overlay network was built; In the Cluster Overlay network, a topology-aware relay search algorithm was designed. The relay search algorithm can find out the optimal relay node to the both sides, thus improving the quality of the path. Finally, this scheme was implemented in the SIP terminal.