Research Of Relay Routing Mechanism In VoIP System

There is low delay requirement in the technology of VoIP design, however, the configuration of BGP(Broader Gateway Protocol) and deployment of Internet infrastructure leads to the routing inefficiency and frequent congestion even path failure of current network layer, which makes the direct connecting can't satisfy the service guarantee of applications as VoIP often require. Although there is someone who has introduced p2p technology into the design of application routing, which could select nodes in better network condition to intermediate the voice packets, thus change the routing way of the network and save the delay by choosing the light load way, the lack of dynamic characteristic makes the effect of relay of these mechanisms a little weak.This paper presents a way based on dynamic promoting Landmark mechanism to resolve Relay problem. The main idea is that, when one node joins the system, it will automatically change its identity to Landmark or just be a cluster node according to its own network situation and relative location. If being promoted to a Landmark, it will manage the cluster peers and provide information to them; peers in communication which need relay, will ask Landmark for candidate relay nodes and then choose the best nodes through test, and begin the sessions of intermediating voice packets through relay node.The mechanism was first programmed in NS2(Network Simulation Version2) network simulation environment, getting a high relay node hit result which is above 70% and a stable ratio of Landmark to cluster peers, which confirmed the feasibility of a real system. At the same time, we compared our result to ASAP(AS-Aware Peer-Relay Protocol), RON(Resilient Overlay Network), SOSR(Scalable One-hop Source Routing), and got the result of the quality routing nodes hit ratio of 35.9% of the total nodes number, comparing to the no more than 1.8% of the total nodes number in RON and SOSR.