An Analysis Tool to Evaluate Effect of Retransmissions on SIP Server Overloading

As the number of mobile application traffic keeps increasing, the operators face the scalability challenges of VoIP protocols. We introduce an analysis tool to evaluate the effect of SIP retransmission mechanism on the SIP server overloading. Our tool is capable of creating various arrival and departure processes using Markov Modulated Poisson Process (MMPP). Extensive numerical experiments are performed by varying mode durations of MMPP and buffer sizes of SIP server. Numerical results indicate that the number of total retransmissions significantly decreases if an incoming request is dropped instead of buffered when the queuing delay of the server has an approximate value of the first retransmission timer. The results provide valuable insights for designing an efficient overload control mechanism for SIP servers.