Signaling Latency Analysis of Peer-to-Peer SIP Systems

Peer-to-Peer SIP (P2PSIP) is proposed to provide fully distributed multimedia communication systems. This paper focuses on analysis of call setup delay "(CSD) of P2PSIP system to evaluate whether it could provide equivalent signaling performance to that of traditional SIP or telephone networks. Call setup delay is composed of lookup latency in DHT overlay and INVITE transaction latency, and mainly decided by Round Trip Time (RTT) experienced on hops and message exchange procedures of lookup and INVITE transactions. Simulation with active measurement RTT data showed that call setup delay ranges widely from under 100 ms to more than ten seconds, and lookup latency takes up more than 60% of call setup delay. It is concluded that P2PSIP system within limited geographic range could achieve acceptable signaling latency, and efficient latency optimization should be considered to ensure the signaling performance when P2PSIP system is used spread across the public Internet.