Layer Two Tunneling Protocol (L2TP)

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Layer Two Tunneling Protocol (L2TP)

You can access a private network through the Internet or other public network by using a virtual private network (VPN) connection with the Layer Two Tunneling Protocol (L2TP). L2TP is an industry-standard Internet tunneling protocol with roughly the same functionality as the Point-to-Point Tunneling Protocol (PPTP). The Windows Server 2003 family implementation of L2TP is designed to run natively over IP networks. This implementation of L2TP does not support native tunneling over X.25 or Frame Relay networks.

Based on the Layer Two Forwarding (L2F) and Point-to-Point Tunneling Protocol (PPTP) specifications, you can use L2TP to set up tunnels across intervening networks. Like PPTP, L2TP encapsulates Point-to-Point Protocol (PPP) frames, which in turn encapsulate IP or IPX protocols, thereby allowing users to remotely run applications that are dependent upon specific network protocols.

The IPX/SPX protocol is not available on Windows XP 64-bit Edition (Itanium) and the 64-bit versions of the Windows Server 2003 family.

With L2TP, the computer running a member of the Windows Server 2003 family that you are logging on to performs all security checks and validations, and enables data encryption, which makes it much safer to send information over nonsecure networks. By using Internet Protocol security (IPSec) authentication and encryption, data transfer through an L2TP-enabled VPN is as secure as within a single LAN at a corporate site. For more information about IPSec, see Internet Protocol Security (IPSec) Encryption.

For more information about VPNs, see Virtual Private Network (VPN) Connections. For information about creating a VPN connection, see Make a virtual private network (VPN) connection.