L2F--Layer 2 Forwarding Protocol. Protocol that supports the creation of secure virtual private dialup networks over the Internet.
L2TP--Layer 2 Tunnel Protocol. Protocol that is one of the key building blocks for virtual private networks in the dial access space and is endorsed by Cisco and other internetworking industry leaders. This protocol combines the best of Cisco's Layer 2 Forwarding (L2F) protocol and Microsoft's Point-to-Point Tunneling Protocol (PPTP).
Layer 2 Forwarding Protocol--See L2F.
Layer 2 Tunnel Protocol--See L2TP.
Point-to-Point Protocol--See PPP.
PPP--Point-to-Point Protocol. Successor to SLIP that provides router-to-router and host-to-network connections over synchronous and asynchronous circuits. Whereas SLIP was designed to work with IP, PPP was designed to work with several network layer protocols, such as IP, IPX, and ARA. PPP also has built-in security mechanisms, such as CHAP and PAP. PPP relies on two protocols: LCP and NCP.
RADIUS--Remote Authentication Dial-In User Service. Database for authenticating modem and ISDN connections and for tracking connection time.
Remote Authentication Dial-In User Service--See RADIUS.
virtual private dialup network--See VPDN.
VPDN--virtual private dialup network. A system that permits dial-in networks to exist remotely to home networks, while giving the appearance of being directly connected. VPDNs use L2TP and L2F to terminate the Layer 2 and higher parts of the network connection at the L2TP network server (LNS), instead of the L2TP access concentrator (LAC).