一、目前我国计算机广域网 没有考虑语音与数据的集成 由于历史原因和体制的原因,我们国家的很多部委(如铁路、民航、电力和石化等)建立了各部委的通讯专网。这些专网主要依赖于卫星和微波信道。这些专网在设计时主要是以语音通讯为主,计算机通讯为辅。语音通讯的传输技术基本上是以传统的TDM技术为主。目前在这些专网上实现的计算机网络互连采用的技术基本上都是从通讯专网里 First, at present, China’s computer wide area network did not consider the integration of voice and data For historical reasons and institutional reasons, many ministries in our country (such as railways, civil aviation, electricity and petrochemical, etc.) established the ministries of the communications network. These private networks rely mainly on satellite and microwave channels. The design of these private networks is mainly based on voice communications, supplemented by computer communications. Voice communications transmission technology is basically based on the traditional TDM technology. Currently in these private networks to achieve the computer network interconnection technology used are basically from the communications network