L2TP

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L2TP

L2TP

(Layer 2Tunneling Protocol) A protocol from the IETF that lets remote users access the corporate network. L2TP allows a PPP session to travel over multiple links and networks. PPP is used to encapsulate IP packets from the user's PC or mobile device to the ISP, and L2TP extends that session across the Internet. L2TP was derived from Microsoft's Point-to-Point Tunneling Protocol (PPTP) and Cisco's Layer 2 Forwarding (L2F) technology. See PPTP and L2F.

From Access Concentrator to Network Server
The "L2TP Access Concentrator" (LAC) encapsulates PPP frames with L2TP headers and sends them over the Internet as UDP packets (or over an ATM, frame relay or X.25 network). At the other end, the "L2TP Network Server" (LNS) terminates the PPP session and hands the IP packets to the LAN. L2TP software can also be run in the user's PC.

Carriers also use L2TP to offer remote points of presence (POPs) to smaller ISPs. Users in remote locations dial into the carrier's local modem pool, and the carrier's LAC forwards L2TP traffic to the ISP's LNS.

L2TP and IPsec
L2TP does not include encryption (as does PPTP), but is often used with IPsec in order to provide virtual private network (VPN) connections from remote users to the corporate LAN. See PPP, virtual private network and IPsec.


PPP and L2TP Traffic
PPP encapsulates IP packets from the user's PC to the ISP. L2TP tunnels those packets over multiple links.
References in periodicals archive ?
In this application, the SMS platforms will act as Layer 2 Tunneling Protocol (L2TP) network servers, enabling the platform to aggregate broadband traffic from other SMS platforms previously installed in their central offices (COs) across Korea.
This comprehensive delivery includes new protocols such as Any Transport over MPLS (AToM) and Layer 2 Tunneling Protocol version 3 (L2TPv3), new deployment capabilities via Cisco Easy VPN and enhancements for integrating IPSec with MPLS.
Furthermore, enterprises must select from multiple protocols, Point-to-Point Tunneling Protocol (PPTP), Layer 2 Tunneling Protocol (L2TP), IP Security (IPSec) protocol and MPLS.
Windows 2000 also supports standard Internet security features such as IP Security, Kerberos authentication, Layer 2 Tunneling Protocol and Virtual Private Networking.
Layer 2 Tunneling Protocol (L2TP) support for the Microsoft Windows VPN client.