Study Of Key Technologies On Multimedia Conferencing System Based On SIP Protocol

With the rapid development of IP technology, real-time multimedia conferencesystem based on IP network increasingly broad application, improve the ability ofmodern office and productivity. SIP is one of the NGN,IPv6, and other mainstreamnetwork signaling control protocol to support streaming media services and videoconferencing service to create, modify and terminate.Service access and the underlyingnetwork separation is the core idea of SIP, but since the IP network has thecharacteristics of distributed and open.it is difficult to guarantee the quality of servicesand eliminate safety hazards.This paper focuses on key technology of real-timemultimedia conference system based on SIP protocol research, focusing on servicequality, audio and video synchronization technology and the protection and security. Ithas several main contents:1) Analysis of the SIP protocol and multimedia conferencing system architecture.And summarized the features and functionality of the SIP protocol, SIP message format,SIP entities constitute the principle of the SIP protocol,six kinds of requests andresponse process.Typical architecture for multimedia conferencing systems based onanalysis of the composition model,and process of loose coupling and tight coupling andmultimedia conferencing systems,the introduction of the RTP/RTCP streamingprotocol,and multicast to reduce the transmission load of the backbone network.2) Study multimedia conferencing systems quality of service safeguards.Clearmultimedia conferencing service quality indicators, analysis of integrated servicemodels,distinguish between the characteristics and performance of the service modeland MPLS technology,the establishment of the business flow based on differentiatedservices, MPLS-TE model,enter the MPLS domain is divided into14levels based ontraffic disposal,according to the different priority, and routing, load balancing, andother measures to ensure the rational utilization of network resources. Transmission ofmultimedia services, audio and video synchronization issues, proposed a RTPtimestamp mapping to RTCP absolute time the NTP axis method, the establishment ofsynchronization between audio and video, and synchronous detection sentencingguidelines.3) Study on multimedia conferencing system based on SIP protocol securitypolicies. According to the text encoding of the SIP protocol characteristics, using the client/server mode, rational use of HTTP authentication, S/MIME, TLS and othersecurity policies.establish a security system for multimedia conferencing system basedon SIP protocol.