Research And Design Of SIP Protocol Stack Based On Embedded Linux

SIP, Session Initiation Protocol, was initially proposed by IETF as an IP phone signaling protocol. Since the first specification for SIP-RFC2543 was delivered in 1999, it has been developing rapidly. Nowadays, SIP is being used as the signaling protocol in fields of 3G mobile telecommunication and NGN. Furthermore, SIP is widely deployed in traditional VoIP applications. The decision to use SIP as the signaling protocol to provide IP multimedia services in the third generation of mobile systems (3G) has dramatically increased the number of people interested in knowing about SIP. SIP is an application-layer control signaling protocol for creating, modifying, and terminating sessions with one or more participants. It can amalgamate traditional telecommunication network application into Internet application and break the traditional telecommunication service model. It provide multimedia service based on IP with Internet rules, so SIP has broad application prospects.At the same time, with the fast development of embedded technology and network technology, embedded communication equipments, such as intellectual phone and personal digital assistant, are more and more used. Embedded equipments could be a node or terminal among network, and should cruise freely between the Internet and other communication networks. A user who only knows the identifier of an equipment, such as e-mail or phone number, could precisely locate it, and can supply multimedia business communications. In this background, how to apply the flexibility and integration of service of SIP to embedded devices, in order to enhance device's communication, connection, session, control, is the stress of our research task.Firstly, the generation and development of soft switch, NGN and SIP are introduced, in order to reveal the SIP background of its birth. Then several open source SIP stacks are discussed in this dissertation. Secondly, the architecture, call flows, syntax, components and entities of SIP are analyzed on the basis of studying RFC3621. SDP and RTP/RTCP, which are the two types of protocol that related to SIP, are introduced.Through the analysis of embedded devices'demand and the research of SIP protocol, the text discuss why we implement SIP protocol in embedded devices and the application foreground of SIP protocol in embedded devices. Based on these works mentioned above, a new implementation of SIP stack with a new kind of hierarchical protocol stack architecture is proposed. At the same time, the architecture, designing and processing flows of each layer are detailed in the dissertation with especially emphasis on their key technologies. Then, under the Linux environment, the SIP source codes are complied and are running successfully. Finally, we design a series of work flow. Based on this, we carry on the detailed test to the protocol stack's function. The result of the test showed the satisfying result.SIP has great potential in embedded domain, and should be further researched and explored. At the end of the text, we exert view and summarization of SIP in embedded system application.