Abstract

The variety of services on IP networks and the need for network technology convergence have resulted in many access networks to adopt the IP technology. The Session Initiation Protocol (SIP) is an end to end application level protocol for establishing, terminating and modifying sessions and has experienced widespread use in IP networks due to its distinguished features such as being text based, independence from the underlying network, and more importantly supporting various types of mobility. In fact these features have lead SIP to be used as the core signaling protocol in the IP Multimedia Subsystem, which is the control plane proposed for next generation networks by the 3GPP community. Nevertheless, the performance of SIP servers when used by the millions of users of the next generation networks is not well established. In this paper we evaluate the performance of SIP servers using a test bed developed at the Iran University of Science & Technology. We consider eight different configurations for SIP server and also study the effect of using TCP and UDP as the transport protocol for SIP packets. We measure several parameters including call setup delay, call failure rate and SIP server throughput. Our results suggest that using SIP in large networks require using special techniques for balancing the load of SIP servers as well as mitigating temporary overloads.