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一、引言 自70年代初萌生了将话音、数据、图像等信息综合在一个通信网内传送即建立综合业务数字网(ISDN)的设想后,ISDN以其能够吸收、综合现有各种公用网的业务,并以数字形式统一处理这些包含在不同媒体中的信息,致使用户可以通过一条用户线借助各种终端进行多媒体通信这一特点,已成为通信网最热门的研究课题,并预示着21世纪主干通信网的发展趋势。
I. INTRODUCTION Since the early 1970s, the idea of integrating voice, data, image and other information into one communication network to establish Integrated Services Digital Network (ISDN), ISDN has been able to absorb and synthesize various existing public networks Of the business, and digital unified treatment of these contained in different media information, so that users can use a variety of terminals through a user-line multimedia communication has become the hottest research topic communications network, and indicates that 21 The Development Trend of Century Backbone Communication Network.