Reliable Session Initiation Protocol (RSIP) signaling with UDP transport using piggybacking method

摘要

Session Initiation Protocol is an IP based application level signaling protocol. SIP is used for locating end users, establishing, modifying and closing multimedia sessions between end users. SIP prefers UDP as transport protocol. Since UDP is not reliable, SIP enables reliability of requests through retransmissions. These retransmissions may result in unnecessary load on the network. This research work proposes a technique to achieve reliability for SIP signaling between servers, with UDP transport, using piggybacking method. The reliability for the SIP signaling is enabled hop-by-hop without disturbing the existing core SIP functionality. We proposed an algorithm for handling SIP request/response message drops. We analyzed the reduction in SIP request retransmissions during message drops. We analyzed and validated the reduction in retransmissions during demand burst condition and with varying round trip times due to server slowdown scenarios. With the proposed system, server recovery time has been reduced by 32.73% during demand burst scenario. With the proposed method, retransmissions have been avoided by 50%.