一、引言浙江大学校园计算机中速网络(PBX—ZUnet)已经建成投入运行,它是一个基于电话自动交换机的网络系统,利用现有的电话交换和线路,所以网络呈星型拓扑,网间互连后,呈随意拓扑。见图1: 其中,专用电话交换机(PBX)既用来连接各种计算机入网,又用来完成电话交换的功能 First, the introduction Zhejiang University campus computer network speed (PBX-ZUnet) has been completed and put into operation, it is based on a telephone automatic exchange network system, the use of existing telephone exchanges and lines, so the network was star topology, inter-network Even with random topology. See Figure 1: Among them, the Private Branch Exchange (PBX) is used to connect both the computer network, but also used to complete the function of telephone exchange