The Message Session Relay Protocol (MSRP) is defined by IETF as a session-oriented for instant message, file transfer,remote desktop sharing, whiteboard for telephone conferences and so on. It’s also adopted by IP multimedia subsystem in 3G networks and becoming as important as RTP. So how to make MSRP work well through NATs have been addressed from various aspects. In this paper we propose the design and implementation of a enchanced SIP ALG that can help MSRP to traverse through NATs based on Connection Tracking and Expectations of NATs. Finally we give the test result of the system on an embedded platform developed as a product router.
['Hai-Bo Yang', 'Hu Lin', 'Jin Li', 'Weimin Lei']
The Design and Implementation of an Enhanced SIP ALG to Support MSRP Sessions