Study Of Media Negotiation In The SIP Protocol

The Session Initiation Protocol (SIP) is an application-layer control (signaling) protocol distributed by IETF for creating, modifying, and terminating sessions with one or more participants. These sessions include Internet telephone calls, multimedia conferences, and multimedia distribution.The Session Description Protocol(SDP) specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. SDP is purely a format for session description - it does not incorporate a transport protocol, and is intended to use different transport protocols as appropriate including the Session Announcement Protocol, Session Initiation Protocol, Real-Time Streaming Protocol, electronic mail using the MIME extensions, and the Hypertext Transport Protocol.The thesis firstly introduces the concept of NGN and softswitch, including the structure, characteristics, and the predominance comparing with the conventional network exchange. With this background, this thesis explores and discusses the embodiment of SIP protocol and its characteristics, as well as the the syntax analysis of SDP protocol and its implementation mechanism . Basing on these aspects, this thesis sums up the various combination of SIP protocol and SDP protocol, and uses the practical cases to further demostrate the applicable situations of these combinations. Additionally, the merits and demerits of these combinations have been analysed in detail. At the end of this paper, a typical SIP operation is taken as an example to analyse and study that how SIP and SDP protocols satisfy the requirements in practice.