论文部分内容阅读
1.前言 作为“信息高速公路”基础设施之一的公用分组交换数据网已于70年代末、80年代初在西方发达国家正式投入使用。而我国是在80年代末、90年代初才开始逐步推广使用,这是我国邮电部门经营和管理的全国性分组交换数据网络。我国的分组交换数据网(简称CHINAPAC)是由31个一级交换中心和各省、区及市内的二级交换中心组成,网络覆盖了全国大部分地、市以上城市和部分县级城市。
1. Introduction As one of the “information superhighway” infrastructure, the public packet-switched data network was officially put into use in the western developed countries in the late 1970s and early 1980s. However, our country began to promote its use gradually in the late 1980s and early 1990s, which is a nationwide packet-switched data network operated and managed by China’s post and telecommunications department. China’s packet-switched data network (referred to as CHINAPAC) is composed of 31 first-tier clearinghouses and provincial, district and municipal secondary exchange centers, which cover most of the cities in China, cities above the county level and some county-level cities.