论文部分内容阅读
综合业务数字网ISDN是为用户提供多种业务和端到端数字连接的新型数字通信网。由于它能利用现有的电话线提供高速、低误码的数据传输,所以广泛地应用于话音、数据、图像传输。传统的Internet接入方式有两种:DDN专线和MODEM。DDN专线速度从64K到2M不等。一般的集团用户都是通过专线访问Internet,就笔者所知,目前很多大学、政府机关选择的DDN专线也只有64K。而ISDN可以达到128K的速率,完全可以满足许多集团用户的需求,而且通过IsDN方式可以大大节约通信费用,所以渐渐为大多数用户所接受。通过ISDN接入Internet方式很多,比如ISDN PC适配卡,TA、ISDN ROUTER(路由器)等,前两种方式一般适用于单用户使用,也能通过安装代理服务器适用于多用户使用。当要访问Internet时,需要手动拨号,不访问时必须手动断掉链路。而且同时上网的用户数量不多,不能实现集团用户访问Internet。采用ISDN ROUTER是一个简单的,很实用的方式,下面我就简单介绍一下这种实现方式。其网络图如右图。
Integrated Services Digital Network ISDN is to provide users with a variety of business and digital end-to-end digital communication network. It is widely used for voice, data and image transmission because it can provide high-speed, low-error-rate data transmission using existing telephone lines. Traditional Internet access in two ways: DDN dedicated line and MODEM. DDN line speed from 64K to 2M range. The general group of users are to access the Internet through the green, as far as I know, many universities, government agencies choose the DDN green only 64K. The ISDN can reach the rate of 128K, fully meet the needs of many group users, and through IsDN way can greatly reduce communication costs, so gradually accepted by most users. ISDN access to the Internet by many ways, such as ISDN PC adapter, TA, ISDN ROUTER (router), the first two ways generally applicable to single-user use, but also through the installation of a proxy server for multi-user use. When you want to access the Internet, you need to manually dial, you must manually disconnect the link when you do not access. At the same time, there are not many users accessing the Internet at the same time, which can not achieve Internet user access. Using ISDN ROUTER is a simple, very practical way, I will briefly introduce this realization. The network diagram as the right.