ITUT协议H323中文.docx

ITUT协议H323中文.docx

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ITUT协议H323中文

国际电信联盟

ITU-TH.323

ITU的电信标准化区段（11/96）

H系列：

视听和多媒体系统

视听服务的基础-视听服务的系统和终端设备

为局域网提供无质量保证服务的可视电话系统和设备

ITU-T协议H.323

（早期由CCITT协议）

ITU-TH系列协议

视听和多媒体系统

用于除电话用途之外的传输信道的特性

H.10.19

用于音频报务的电话型电路的使用

H.20.29

用于各种类型的电报传输或同步传输电话电路或电缆

H.30.39

用于传真电报的电话型电路

H.40.49

数据信号的特性

H.50.99

可视电话系统的特性

H.100.199

视听服务的基础构架

H.200.399

通则

H.200.219

多路传输和同步传输

H.220.229

系统概况

H.230.239

通信过程

H.240.259

运动视频编码

H.260.279

相关系统概况

H.280.299

视听服务系统和终端设备

H.300.399

细节请参见ITU-T系列协议。

ITU-T协议H.323

为局域网提供无质量保证服务的可视电话系统和设备

摘要

H.323协议描述了基于无质量保证服务的局域网（LAN）上的多媒体通信的终端，设备和服务。

H.323终端和设备可以传输实时语音、数据和视频，或上述的任意组合，包括视频电话。

用于H.323终端通信的LAN，可以是单个网段或令牌环网，也可以是多个具有复杂拓补结构的段。

注意：

基于多个LAN网段上（包括Internet）的H.323的终端工作性能可能很低。

保证这种类型的LAN/互联网的服务质量的可能方法超出了本协议的范围。

H.323终端可以被集成进PC或在像视频电话这种独立设备上实现。

支持语音是必须的，而支持数据和视频是可选的，但是一旦支持的话，就必须具备使用特定通用方式的操作的能力，这样所有支持该媒体形式的终端就能互相协作。

本协议允许每种媒体类型的多通道同时使用。

H.323系列协议还包括：

H.225.0打包和同步，H.245控制，H.261和H.263视频编码器，G.711、G.722、G.728、G.729和G.723音频编码器，以及T.120系列多媒体通信协议。

本协议利用了H.245协议的逻辑信道信令进程，当通道打开时每个逻辑信道的内容已被描述好了。

对接收器和传送器能力的表示由进程提供，因此传输被限制什么接收器能译码上，这样接收器可以请求传送器的特定方式。

由于H.245协议的进程也用于ATM网的H.310协议以及GSTN和V.70的H.324协议中，因此与这些系统的协作应该不会要求H.225～H.245协议的传输达到与H.320系统相同的情况。

H.323终端可以用于多点配置，也可以和B-ISDN上的H.310终端，N-ISDN上的H.320终端，B-ISDN上的H.321终端，保证服务质量的LANs上的H.322终端，GSTN和无线网络上的H.324终端，以及GSTN上的V.70终端相互协作。

来源

ITU-T协议协议H.323是由ITU-T第15研究组（1993-1996）撰稿，并于1996年11月8日经WTSC决议的NO.1程序认可。

绪言

ITU（国际电信联盟）是联合国在电信领域中的专门机构。

ITU电信标准化区段（ITU-T）是ITU的永久性机构。

ITU-T负责研究技术，操作，征询问题以及在全球标准化通信方面制定标准协议。

世界电信标准化会议（WTSC），每四年召开一次，为ITU-T研究组的研究工作制定论题，然后ITU-T研究组为这些论题制定协议。

由ITU的成员核准的协议必须通过WTSC的NO.1解决方案的程序核实。

在信息技术的一些区域内，在ITU-T范围内，必要的标准由ISO和IEC共同制定。

说明

在本协议中，表达式管理机构是用于精确指示电信管理和识别操作机构的。

知识产权

ITU1997保留所有的权利。

1概况······································································1

2标准的参考································································2

3定义······································································3

4符号和缩写································································8

5常规······································································10

6系统描述··································································10

6.1信息流··································································10

6.2终端特性································································11

6.2.1本协议以外的终端元素··············································11

6.2.2本协议以内的终端元素··············································12

6.2.3LAN接口···························································12

6.2.4视频编码··························································12

6.2.5音频编码··························································13

6.2.6接收路径迟延······················································14

6.2.7数据通道··························································14

6.2.8H.245控制函数·····················································16

6.2.9RAS信号函数·······················································20

6.2.10呼叫信号函数·····················································20

6.2.11H.225.0层························································21

6.3网关特性································································21

6.4网闸特性································································24

6.5多点控制器特性··························································25

6.6多点处理器特性··························································26

6.7多点控制单元特性························································27

6.8多点能力································································27

6.8.1中心多点能力······················································27

6.8.2非中心多点能力····················································27

6.8.3混合多点-中心音频·················································28

6.8.4混合多点-中心视频·················································28

6.8.5建立常规模型······················································28

6.8.6多点速率匹配······················································29

6.8.7多点边缘同步······················································29

6.8.8多点加密··························································30

6.8.9级联多点控制单元··················································30

7呼叫信号·······························································30

7.1地址····································································30

7.1.1LAN地址···························································30

7.1.2TSAP标识符························································30

7.1.3别名地址··························································30

7.2注册，管理和状态通道····················································31

7.2.1网闸的发现························································31

7.2.2端点注册··························································32

7.2.3端点定位··························································33

7.2.4许可，带宽改变，状态，断开········································34

7.3呼叫信号通道····························································34

7.3.1呼叫信号通道路由选择··············································34

7.3.2控制信道路由选择