Layer Two Forwarding (L2F)

Layer Two Forwarding (L2F) is a Cisco tunneling protocol that uses virtual dial-up networks for secure data packet transport. L2F functionality is similar to the Point-to-Point Tunneling Protocol (PPTP), which was developed by the Microsoft-led PPTP Forum.

L2F is part of the Layer 2 Tunneling Protocol (L2TP) standard (RFC 2661).

L2F creates point-to-point (PPP) network and user connections and allows high-level protocols to create tunnels via the link layer, including High-Level Data Link Control (HDLC) or SLIP frames. These tunnels separate server and termination points to facilitate network access.

In 1999, Microsoft and Cisco merged their respective L2F protocol versions and created L2TP, which is the Internet Engineering Task Force (IETF) tunneling standard.