Understanding VPNs and the VPN Gateway

Virtual private networks (VPNs) enable users to connect to a remote private network through the Internet. Virtual private networks therefore span the Internet because the user connects over the Internet to the remote VPN server. With a VPN, data is first encrypted and encapsulated before it is sent to the remote VPN server. When the VPN server obtains the data, it decrypts the packet so that is can be interpreted.


VPNs are usually implemented to provide for the following scenarios:
Enable remote access users to connect to and access the network.
Provide connectivity between two or multiple private networks or LANs.
A VPN gateway, also called a VPN router, is a connection point that connects two LANs which are connected by a nonsecure network such as the Internet. A VPN gateway therefore connects to either a single VPN gateway, or to multiple VPN gateways to extend the LAN. This scenario is typically referred to as a router-to-router VPN. The corporate networks are connected through the VPN servers running Routing And Remote Access (RRAS). The actual medium that connects the LANs is usually the Internet. This means that the VPN gateway or router will be configured with the address on the LAN that it is connected to, and a public IP address.