Research and implementation of fault-tolerant mechanism based on SIP call control

Session Initiation Protocol has been a hot issue in implementation of VoIP systems as its simpleness, flexibility and high-scalability, but the unreliability of SIP communications has affected the QoS of SIP Session. In order to improve the reliability of SIP communications, a solution of SIP fault-tolerant mechanism was introduced in this paper. It contained two aspects, one was SUA (State Update Algorithm) which used for producing and sharing Session State Message in server, and the other one is LRSA (Listen Retransmission Switch Algorithm) which used for switching SIP request to one certain server. This paper also have validated and analyzed the SIP fault tolerant mechanism by experiment. According to the result of the experiment, it shows that fault-tolerant mechanism based on SIP can improve the reliability of SIP communications.