A P2P-Grid Model for Traversing NAT in SIP Communication

Session Initiation Protocol (SIP) standardized by IETF provides a way to establish the sessions between Internet telephony devices, but this protocol canpsilat work with Network Address Translator (NAT). Therefore how to make SIP NAT friendly becomes a worthy topic. This paper proposes an efficient approach P2P-Grid architecture model based ICE which uses Simple Traversal of User Datagram Protocol (STUN) and TURN synthetically at the beginning of Interactive Connectivity Establishment (ICE) process (establishing the multimedia sessions), the agents ignore their own NAT topologies. In the process of establishing sessions, agents explore the NAT topology by a request / response interaction, and a smart sorting algorithm is also used to find and select the optimal path for media streams to traverse NAT. The program was tested on Linux platform. The result shows that the media streams can traversal various NAT efficiently.