Evaluating SIP server performance

SIP is a protocol of growing importance, with uses for VoIP, instant messaging, presence, and more. However, its performance is not well-studied or understood. In this extended abstract we overview our experimental evaluation of common SIP server scenarios using open-source SIP software such as OpenSER and SIP prunning on Linux. We show performance varies greatly depending on the server scenario and how the protocol is used. Depending on the configuration, through put can vary from hundreds to thousands of operations per second. For example, we observe that the choice of stateless vs. stateful proxying, using TCP rather than UDP, or including MD5-based authentication can each can affect performance by a factor of 2-4. We also provide kernel and application profiles using Oprofile that help explain and illustrate processing costs. Finally, we provide a simple fix for transaction-stateful proxying that improves performance by a factor of 10. Full details can be found in our accompanying technical report.