Technical Information for VPN: Introduction
Your computer can be connected to the Internet in many different ways - via a telephone modem, cable or DSL modem, wireless connection, or other dedicated line. From home, most people connect to an Internet Service Provider (ISP), such as Time-Warner, Telesys, EarthLink, AOL, etc. All ISPs, in turn, connect to the Internet backbone, a web of super high-speed connections that connect various primary nodes of the Internet. (In the diagram below, the Internet appears as a "cloud," a common way of displaying a mixed computer network.) In this manner, you can communicate with other computers that are connected to the Internet.
A virtual private network (VPN) connection is a secure "tunnel" formed between a private network and a remote machine connected anywhere on the Internet. The server controlling the connection and the remote machine can reside on the same network (for instance, a server and desktop within the same department), or they can be remote (such as a server in Austin and a personal machine in Houston).
The most important thing to remember is that a VPN connection requires an active Internet connection. You need to connect to your ISP normally before establishing a VPN connection.