從L2TP協(xié)定入手，介紹了L2TP協(xié)議的基本技術和撥號訪問服務器及L2TP網絡服務器，詳細闡述了在此基礎上建立的認證模塊、日志模塊和LAC模塊，并對用L2TP創(chuàng)建VPN進行了探索，在多種UNIX環(huán)境下建立了原型，積累了建立VPN的經驗，為其他VPN的建立打下了基礎。
關 鍵 詞 虛擬專用網; 第二層隧道協(xié)議; 隧道; L2TP集中器; L2TP網絡服務器

Abstract Virtual private network is the key technology of next generation Internet, L2TP is a dialup virtual private network specification which was defined by IETF. Its design and implementation are very significant. From the L2TP, basic technology and two kinds of servers of L2TP(LAC server and L2TP net server) are introduced and L2TP function models(authentication model、log model and LAC model) on this are expatiated. Based on this, a L2TP scheme was suggested and developed on a few UNIX latforms.
Key words virtual private network; L2TP; tunneling; LAC; LNS