Since it operates over Internet connections available to anyone, it eliminates the need for special dedicated circuits for an agency's extranet connections, to suppliers or other agencies. And it can make those connections more secure and easier to manage. A VPN can be established at several points in the network connection. They also often offer the advantage of additional security and much better network management features. In the past, when we just couldn't avoid it, we could set up special secure connections so somebody could get to these things.
Internet connections are ubiquitous, and they're inexpensive.
The server sees a user from a VPN as just another client on the network, even if that user is not physically present. We have the luxury of being able to choose our bandwidth, choose our access point and still save quite a bit of money on connection costs. The widespread deployment that some Oak Ridge officials had hoped for has yet to materialize. While a few users are connecting back to headquarters via tunnels, the lab's VPN trial remains a small one, mainly because of problems with incompatible standards and the high costs of proprietary solutions. We started with Microsoft's PPTP, mainly because it was free, but we've also looked at commercial products, like FireWall-1.