Measurement of the SIP Parsing Performance in the SIP Express Router

Future telephony and multimedia systems will use the Session Initiation Protocol (SIP) for signaling purposes. SIP is a text-based protocol that imposes challenges for an efficient message processing. The ability of SIP entities to process SIP messages quickly is crucial for the performance of these networks, which often have strict timing requirements, e. g., to keep the call setup delays small. This paper studies the performance of SIP message processing in SIP proxies, focusing mainly on the impact of message parsing. We perform a detailed delay analysis for the widely used SIP Express Router (SER). Our measurements show that message parsing actually contributes significantly to a SIP proxy’s processing efforts, and therefore confirm other existing studies. However, our results also show that the overall delay in high-performance SIP proxies is stronger affected by other factors, in particular the operating system.