Outlining the PPTP and L2TP Protocols

Both PPTP and L2TP are based on the well-defined Point-to-Point Protocol (PPP) and are accepted and widely used in various VPN implementations. L2TP is the preferred protocol for use with VPNs in Windows Server because it incorporates the best of PPTP, with a technology known as Layer 2 Forwarding. L2TP allows for the encapsulation of data over multiple network protocols, including IP, and can be used to tunnel over the Internet. The payload, or data to be transmitted, of each L2TP frame can be compressed, as well as encrypted, to save network bandwidth.

Both PPTP and L2TP build on a suite of useful functionality introduced in PPP, such as user authentication, data compression and encryption, and token card support. These features, which have all been ported over to the newer implementations, provide for a rich set of VPN functionality.