H.323

In the traditional phone system, a phone call from the establishment of system connected to dismantle connections are needs certain signaling to assist complete. In the same, IP telephone, how to find the called party, how to establish response, how to each other's data processing ability to send data, also need the corresponding signaling system, commonly known as the agreement. At present in the world, more influence IP phone aspects of the agreement includes ITU-T puts forward of h. 323 agreement and put forward the IETF SIP protocol, this article introduces this section with the most widely h. 323 agreement.

System structure

In order to guarantee the QoS in packet-switched network multimedia conference, launch by ITU the 15 the team SG-16 in 1996 through the h. 323 advice of the first edition in 1998, and put forward the h. 323 second version. H. 323 make no QoS (quality of service) ensure that the grouping of network PBN (packet Based on grow independently) of the multimedia communication system standard, the packet network rules the today's desktop network system, including Based on TCP/IP, the IPX packet switching Ethernet, fast Ethernet, token nets, FDDI technology. Therefore, h. 323 standard for LAN, WAN, Internet, Internet, multimedia communication technology applied to provide the basis.

H. 32 x part

H. 323 is ITU multimedia communication series standard h. 32 x part of this series of standards make existing communication network in the video conference, including possible, h. 320 is in N-ISDN on the multimedia communication standard: h. 321 is in B-ISDN on the multimedia communication standard: h. 322 is a service in quality assurance of the LAN on the multimedia communication standard: h. 324 is in GSTN and wireless network for multimedia communication standards. H. 323 for the grouping of existing network PBN (such as IP network) provide multimedia communication standards. If the IP and other techniques such as the IETF resources reserve agreement, and the combination of RSVP can realize the IP network multimedia communication. Based on IP LAN is becoming more and more powerful, such as IP over SONET/SDH, IP over ATM technology is rapid development and LAN broadband is continually improved. It can provide equipment and equipment, application and application, supplier and the suppliers of interactions between the ability, therefore, h. 323 to ensure that all h. 323 compatible device interoperability. The higher rate of processor, growing by the graphics device and strong multimedia chip to accelerate to PC becoming more and more powerful multimedia platform. H.264 can provide PBN and other network multimedia communication between the interconnection standards communication. Many computer, network communication companies, such as the intel-based, Microsoft and Netscape support h. 323 standard. H. 323 standard included in the group that no QoS network multimedia communication in the technical requirements. These include a packet network LAN, WAN, Internet, Internet and use the PPP etc/group agreement through the GSTN or ISDN dial-up or pointtopoint connection.

Frame construction

Overall, the h. 323 is a framework construction, it involves terminal equipment, video, audio and data transmission, communication control, a network interface aspects of content, including the composition more meeting more control unit (MCU), a multipoint control unit (MC), more processor (MP), gateway and shut to keep equipment. It is the basic component unit "domain", in h. 323 system, the so-called domain is refers to a close by keep management, gateway, and more control unit (MCU), a multipoint control unit (MC), more processor (MP) and all of the terminal set. A domain at least contain a terminal, and must have and only a close together. H. 323 system in all logic components called h.323 entity, its sort has: terminals, gateway, multipoint control unit (MCU), a multipoint control unit (MC), more processor (MP). One terminal, gateway, multipoint control unit (MCU) is h. 323 terminal equipment, is the network in logic unit. Terminal equipment is can call and call, and some entities are not called, such as close together. H. 323 includes h. 323 terminals and other terminal, through the different between the network and the end-to-end connection.