Research Of Real-time Data Transport Between Low Rate Data Network And LAN

With the fast development of network and multimedia technique, the research on the application of network multimedia has become one of the hotspot of the computer application technique research. One trait of the network multimedia application is higher requirement on the real-time reality. Meanwhile, the traditional protocol of the transport layer, for example, TCP/UDP can't match the need of running a real-time based application. This paper makes some analysis and research about RTP/RTCP, designs a gateway model that could process real-time communication through different architecture networks, and also describes the flow of the model's functions.As theoretical background, this paper first introduces the stream transport process including the category, technological theory and the main ways to play the stream media. After that, the paper analysis the requirement for the communication network to run a real-time multimedia application, besides that, also analysis the capabilities and disadvantages of the existed communication network to support real-time transport.The paper gives a brief introduction about the gateway technology, and then describes three categories and their subcategories of gateway in details.Then, this paper introduces some background knowledge of the communication protocol. Introduces the OSI 7 layer model and TCP/IP protocol stack, explains why the current transport layer protocols~UDP/TCP don't qualified for real-time datatransport. So, the RTP/RTCP comes out consequently. The paper emphasis on the content of RTP/RTCP, describes the main functions, frame format, parameters of RTP/RTCP. There are two types of RTP-level relay, called mixer and translator, the RTP supports these two applications. At the last part of RTP/RTCP theory, the paper shows how to resolve the SSRC identifier collision and how to detect loop.To run TCP/IP protocol stack over serial links, the paper imports the concept of SLIP which can encapsulate standard IP packet over serial link. Meanwhile, the paper also points out several limitations of the SLIP.At last, the paper gives the RTP/RTCP package's data structure in C++ language, and also the implement flows of RTP/RTCP. Based on SLIP, the paper makes some modification and improves the SLIP to adapt to RTP/RTCP. The paper describes how the enhanced SLIP to encapsulate, send, receive and de-encapsulate data.Based on the foregoing researches and works, the paper designs a model to implement data gateway in software, which can communicates real-time data between two different architecture networks.