| In recent years,the telecommunication network of our country develops rapidly,has made a huge progress,and the ability of synthesis corresponds enhanced obviously. Numerous correspondence companies and network companies from domestic and foreign countries, spares no effort to promote each product to increase the network band and raises the transmission speed. From ordinary telephone line to communication fiber optics, from simulates the switchboard to the digital switchboard, from analog transmission to digital wide band, the correspondence band width was getting more and more wide. A wideband communication's important symbol is the video image correspondence application. As video image's data quantity is very big, when using traditional communication to receive transmits the band width the transmission speed restriction, so the video frequency application's communication must have the wide band wire support which adapts with it. At present although the domestic and foreign wideband communication infrastructure already had the suitable scale, on the wide band concrete application also relatively lags. Our "the road"is very already wide, but"the vehicle"are also quite few on this road. This is precisely the opportunity which the video-conference develops.At present, in video-conferencing system domain, especially in special net, the video-conferencing system is generally based on 20 century's ends H.320 frame agreement (namely based on circuit switching transmission network video-conference standard frame agreement) video-conferencing system. Its image resolution is bad, hardly satisfying when requesting image, pronunciation quality in a high application situation for instance long-distance teaching, long-distance medical service, military command. At the same time, its correspondence signaling mechanism is complex, the stability is bad, the efficiency was low, has affected video-conferencing system's application. Along with H.323 as well as the standard which is connected with H.323 the formulation, had suddenly the progress based on the IP net's multimedia conference service's research, caused to be possible to well develop in the IP on-line multimedia video-conference service. How does the telecommunication enterprise construct one based on the H.323 video network, take IP the net as the core, unified load bearing pronunciation, data, video frequency, this is the topic which is worth studying.This article firstly have conducted the full research on the H.323 standard's principle of design, the agreement stack structure, the system structure and the related important agreement and so on, proposes above this foundation under the existing network condition, China Unicom constructs based on the H.323 video network plan. Then it aims at the market and the linked company network actual state, has given penetrates the user flank defense wall with flues for heating's solution with other H.323 system interconnection intercommunication plan and with the agent software. Finally service which and can provide according to the link company access network construction situation, proposed the subscriber's premises turning on way and the concrete application case. This topic research content has strong pointed and the practical significance regarding the current wide band video network construction development.The H.323 system's building block is called the H.323 entity (entity), it includes terminal, gateway, net floodgate, multi-spot controller (MC), multi-spot processor (MP) and multi-spot control unit (MCU-Multipoint Control Unit). And, the terminal, the gateway and MCU are called as the vertex; the vertex may initiate the call, may also accept the call, the media information flow or terminates in the vertex production. And, the terminal, the gateway and MCU are called as the vertex; the vertex may initiate the call, may also accept the call, the media information flow or terminates in the vertex production.Public video switching network including video operation support level, service level, load bearing level and transmission level(1) Transmission levelThe transmission level main use existing foundation network, provides physics transmission path.(2) Load bearing levelThe load bearing level the network which has the grade of service to guarantee transmits the platform for video provision of service one, realizes the video service end-to-end transmission. The China Unicom public video switching network load bearing network uses the lamination network architecture, divides into the backbone level, the service gathering level and the turning on level.(3) Service levelService level including three sub-stratification planes: Media processing level, multi-spot exchange level and signaling key-course. (4) operation support levelThe operation support level carries on the management, the maintenance, the cost and the tent to the public video service, including business management system, cost/billing system and network management system.The public video switching network provides service:(1) Multi-spot conference service(2) Videophone service(3) Enterprise VPN service(4) Corresponds with the voice network(5) Data conferencing serviceThe operator through based on the H.323 video network construction, provides the integrated pronunciation, the data, the image, the video frequency comprehensive service based on the IP technology, but introduces fast has the variation and the competitive power service, provides the multi-services in view of the new customer, attracts the old customer to use the new service, thus sharpens the communication network service innovation ability effectively, and solves the service innovation bottleneck from the deep level.Does the technical difficulty which meets in the H.323 video net research how lie in the H.323 video net to realize the telecommunication level QoS safeguard. Therefore this article proposed in the H.323 video net plan has the network which the grade of service guaranteed to transmit the platform concept, the load bearing H.323 video net's IP network build, in link already in the nationwide scale construction completed in the ATM network, the use existing ATM network load bearing net provides the QoS safeguard to H.323 the video net's IP.In H.323 video network design and project actual, but also proposed the solution to the below key question:(1) In view of the interconnection intercommunication question, this article proposed with other operator H.323 network intercommunication and with the enterprise special-purpose H.323 network intercommunication plan;(2) Regarding the video net security problem, this article proposed between the special net's isolation and the net interconnects solution;(3) Regarding passed through the user firewall's question, this article proposed separately in the backbone network and in the network in solution;(4) Regarding the IP address question, this article proposed the plan and the operational version. Through the H.323 video net's construction, the link will have provided the following service the ability and for present's service innovation, the development has built the solid network foundation:(1) Video services this locality, two-way communication;(2)Realizes the voice network and the video net are in voice feature intercommunication;(3) Realizes the video net and Internet's in video service intercommunication;Through this topic's research, we see the telecommunication enterprise sets up the H.323 video network through the research, may open the new telecommunication service market for the telecommunication enterprise, open the new profit space, realizes the variation competition for the operator in the intense telecommunication market to provide the brand-new business model. |
PDF Full Text Request