大家知道,在X.25分组交换网投产以前,实现Novell网的远程访问一般采用基于电话网异步传输的方案,即采用电话拨号,或采用电话专线。通常利用一块广域网卡WNIM+卡(Wide-Area Network Interface module),以及Novell网远程访问服务程序(Netware Access Services,简称,NAS)来实现。远程访问服务器往往采用多条电话线路方式,可使远端几个用户同时入网。一般需要个4～8个调制解调器,4条～8条电话专线(或4个～8个电话)。显然这样费用太高,会浪费许多物理线路。由于走的是电话网,线路可靠性很低,所以传输速率不能太高。随 We all know that in the X.25 packet switched network put into operation before the realization of Novell network remote access generally based on the telephone network asynchronously transmission program that uses the telephone dial-up, or the use of telephone lines. This is usually done using a WNIM + card (Wide-Area Network Interface module) and Novell Netware Access Services (NAS). Remote access servers often use multiple telephone lines, allowing several users to access the network at the same time. Generally need a 4 ~ 8 modems, 4 to 8 telephone lines (or 4 to 8 phones). Obviously such a fee is too high, it will waste a lot of physical lines. Due to take the telephone network, line reliability is very low, so the transfer rate can not be too high. With