A simple method for VPN is PPTP. It is a software based VPN system that uses your existing Internet connection. By using your existing Internet connection, a secure “tunnel” is created between two points allowing a remote user to connect to a remote network. You can setup this type of connection with various types of software or hardware. Windows Server has a PPTP build-it and you can connect to it via a native VPN client within Windows.

Site-to-site is similar to point-to-point except there is no “dedicated” line in use. Unlike point-to-point, the routers at both ends do all the work. They do all the routing and encryption. This is an easy way to connect two offices without having each user “dail-up” using a PPTP connection. Site-to-site VPNs can work with hardware or software-based firewall devices

A traditional VPN can also come as a point-to-point. These are also referred to as “leased-line VPNs.” Simply put, two or more networks are connected using a dedicated line from an ISP. For example, T1′s, Metro Ethernet, DS3, ATM or something else. The main strength of using a leased line is the direct point-to-point connection. It does not go out over the public Internet, so there performance is not degraded by routing problems, latency, and external congestion

MPLS is a true “ISP-tuned” VPN. It requires 2 or more sites connected via the same ISP or an “on-net” connection*. There is a way to configure this using different ISP’s or “off-net” but you never get the same performance. While it does use your existing Internet connection, tweaks are made by your ISP for performance and security.