虚拟专用网（Ｖｉｒｔｕａｌ Ｐｒｉｖａｔｅ Ｎｅｔｗｏｒｋ，ＶＰＮ）是利用公共同资源为客户构建的专用网。很多构建ＶＰＮ的方案已经被提出并实施。最近，ＩＥＴＦ提出的使用虚拟路由器（Ｖｉｒｔｕａｌ Ｒｏｕｔｅｒ，ＶＲ）构建ＶＰＮ的方案不但与原有的方案完全兼容，而且使 ＶＰＮ的构建变得更加灵活和简单。本文介绍了该方案的基本原理与关键技术。 Virtual Private Network (VPN) is a private network constructed for customers by using public resources. Many schemes for building VPNs have been proposed and implemented. Recently, the proposal of IETF to construct VPN using Virtual Router (VR) is not only fully compatible with the original solution, but also makes VPN construction more flexible and simple. This article describes the program’s basic principles and key technologies.