五、广域网 广域网实际上可称为通信子网,一般采用点到点通信技术。它包含一组复杂的交换技术,通过通信线路连接起来,形成网状结构。广域网的建设和管理,通常由邮电、军队等专业部门进行。我们只是租用其通道和技术手段,实现自己的网络功能。 目前,我们可以使用的广域网主要有:公用电话网、公用分组交换网(X.25)、数字数据网(DDN)、卫星网络。 Fifth, WAN WAN actually can be called a communication subnet, generally using point to point communication technology. It consists of a complex set of switching technologies that are connected by communication lines to form a mesh structure. WAN construction and management, usually by the postal and telecommunications, military and other professional departments. We just rent their channels and technical means to achieve their own network capabilities. Currently, we can use the wide area network are: public switched telephone network, public packet-switched network (X.25), digital data network (DDN), satellite network.