With the rapid development of the telecom technology, various kinds of data communication technologies appear, namely, DDN, packet switching technology(x. 25), FR, ATM, IP switching and MPLS.

• 随着电信技术的迅速发展；数字数据网DDN；分组交换技术X.；25；帧中继FR和异步转移模式；IP交换；多协议标记交换MPLS等多种数据通信技术应运而生。