The Decoding And State Analyzing Of System H323

With the quickly development of the Internet network, some traditional telecom services move to Internet network., in which, voice of IP is a such service develops very speedily. Because of the born open configuration of Internet network, traditional telecom services got many new characters in the course of moving. The voice of IP based on open standard can provide voice telecom service with diversified mode.H.323 is advanced for multimedia conference system, which includes audio and video, which can be used for the standard of voice of IP. Openh323 item is used for implement the frame of H323 recommendation , the protocol library accord H323 completely, which can communicate with any other software according with H323 recommendation, implements all functions such as call out, connect, transmit data or media data defined in thatOn Internet network nowadays, the application of voice of IP has become a keystone for network research increasingly. To get better application and exploitation for voice of IP, it is indispensable for comprehending the H323 signaling transmitting on the network .In the course of exploiting H323, the tool for analyzing signaling is very important, which can detect whether the specification is accord with the H323 recommendation, whether there is problem in the course of communications, etc..First, this text describes the mostly content of H323 system, such as its elements including Terminals, Gateways, Gatekeepers and MCUs and their functions and how they contact each other in addition. Otherwise, it describes the signaling protocol of H323 and their effect in the course of communication. And it depicts how call connect is completed and how media channel is build and so on.Then, the structure and mode of network analyzing and basal elements are mentioned. Network analyzing means capture the data packets streams on the network, then transform it to readable form, discover the problem of network, wit checking the inner data of that packet, otherwise, it detects how equipments communicate, checks the capability of network. Network analyzing analyzes the capability of network and discovers choke point of network, watches the traffic of network and the behavior of network protocol, realizes the run state of network. Next, this text describes how the plugin named ethereal-h323-plugin analyses the three leading signaling including RAS signaling, H225 signaling and H245 signaling.Last, It used three personal computers and every computer built openh323, two installed ohphones and the last installed opengk, then, they can communicate with each other. Choose one computer and install ethereal software and plugin...