Formal Modeling and Analysis of SIP Using Colored Petri Nets

The Session Initiation Protocol (SIP), which is wildly used for IP-based multimedia communication, is an application-layer protocol to handle sessions between two points. SIP is implemented on the top of user datagram protocol (UDP) or transmission control protocol (TCP). This study proposed a Colored Petri Nets (CPN) based formal model of the INVITE transaction of SIP over reliable and unreliable transport channel. Then, simulation and state space analysis are utilized to validate the model and verify some higher functional properties of SIP. The proposed formal model could not only be served as an unambiguous and visual formal specification of SIP, but also facilitate protocol behavior simulation and properties analysis.