随着人类社会的不断进步、经济的迅猛发展以及计算机的广泛应用，人们对信息的要求越来越强烈，为了更有效可靠地传送、处理信息，便产生了计算机通信网。实际上，计算机通信网和我们的生活息息相关，网上邮件、网上聊天和网上购物已悄悄走进百姓生活，局域网、资源共享也在企 With the continuous progress of human society, the rapid economic development and the extensive application of computers, people have become more and more demanding on information. In order to transmit and process information more effectively and reliably, computer communication networks have emerged. In fact, the computer communication network and our lives are closely related to e-mail, online chat and online shopping has quietly into people’s lives, LAN, resource sharing is also in the business