摘要
大系统理论与信息业的结合是信息产业发展的新阶段，分级递阶控制的思想在
网络技术中的应用越来越受到重视。本研究以陕西省西安大唐电信公司-IP电话项目
为研究对象，将大系统的观点应用于IP电话网络，分析、设计并实现了基于ITU-T
H.323协议栈的IP电话网络的中心控制部件—网守（Gatekeeper，GK）。
本文主要介绍了H.323的基本结构和信令及网守的主要功能，通过对IP电话网
络和原有网守应用中局限性的分析，应用分级递阶控制理论思想，提出了网守分级
管理的VoIP系统模型。根据系统的需求，对网守实现中的一些重要问题如路由、记
费、认证、呼叫流程和服务质量等进行了分析，并提出了基于H.323的整体框架和
信令结构的解决方案和策略。并将微内核操作系统的构造思想应用于网守的设计，
并进行了实现。
目前，网守在静态调试和系统联调过程中性能良好，达到预期的目标。包括网
守在内的西安大唐电信公司VoIP系统业已通过信息产业部的专家鉴定，获得国家电
信设备入网证书。
The combination of theories of large scale system and information industrial is the
new phase of the development of information industrial. And the method of hierarchical
control is becoming more and more important in network technology. This research is
based on the IP telephone project of Xi'an Datang Telephone Corp, the famous Chinese
telecom equipment manufacturer. After applying method the hierarchical control to the
VoIP system, writer designs and develops the central controller of VoIP system based on
ITU-TH.323-- Gatekeeper.
Basic structure and signaling of H.323 protocol is introduced, as well as the primary
functions of Gatekeeper. A hierarchical VoIP network model based on Gatekeeper is put
forward through analyzing the shortage of gatekeepers?currently working way and
applying the thought of hierarchical control. Some problems in the implementation of
gatekeeper such as routing, billing, authentication function, call signal flow and quality of
service are analyzed. Solutions and strategies based on the main frame and signaling -
characteristics of H.323 protocol are put forward accordingly. The design. scheme and
realization of gatekeeper are described.
The project puts up good performance in simulating environment. The total VoIP
system of Xi抋n Datang Telephone, gatekeeper included, has been passed the
authentication of Ministry of Information Industrial, and been granted the right to access
telecom net.
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