A Novel Application-layer Relay Strategy for Low Delay P2P SIP VoIP System

Development of Internet brings the great increasing communication requirement. This demand impels the developing progress of Voice over Internet Protocol (VoIP). It is difficult to supply the high quality user experience for VoIP services, which has brought great challenges to VoIP developer because of the dynamic property of Internet. We obtain the following results in lots of existing VoIP systems: (1) many relay peer selections are suboptimal; (2) the waiting time to select a relay node can be quite long; (3) there are a large number of unnecessary probes, resulting in heavy network traffic. This paper presents a way called novel application-layer relay strategy (NARS) to solve relay problem and improve scalability. We introduce the mechanism in detail, and test our mechanism in NS2 network simulation environment and get a high relay node hit ratio result, which confirms the feasibility of NARS. Also we make a comparison with the other existing models.