1. Remote-access VPN
Remote-access, also called a virtual private dial-up network (VPDN), is a user-to-LAN connection used by a company that has employees who need to connect to the private network from various remote locations.
Example of a company that needs a remote-access VPN would be a large firm with hundreds of sales people in the field.
Remote-access VPNs permit secure, encrypted connections between a company's private network and remote users through a third-party service provider.
1. Intranet-based: Site-to-Site VPN
If a company has one or more remote locations that they wish to join in a single private network, they can create an intranet VPN to connect LAN to LAN.
1. Extranet-based: Site-to-Site VPN
When a company has a close relationship with another company (for example, a partner, supplier or customer), they can build an extranet VPN that connects LAN to LAN, and that allows all of the various companies to work in a shared environment.