Compared with the conven-tional dedicated lines such as leasing DDN and FR,establishing secure Vir-tual Private Dialing Network(VPDN)over Internet or other public networks can save a lot of communications fees and management costs for the enter-prises.

• 与传统的租借DDN和fr等专用线路相比,在Internet或者其他的公用网之上建立安全的虚拟拨号网络(VPDN),可以为企业节省大量的通信费用和管理费用。