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L2F, or Layer 2 Forwarding, is a tunneling protocol developed by Cisco Systems, Inc. to establish virtual private network connections over the Internet. L2F does not provide encryption or confidentiality by itself; It relies on the protocol being tunneled to provide privacy. L2F was specifically designed to tunnel Point-to-Point Protocol (PPP) traffic.^[1]

Use

Virtual dial-up allows many separate and autonomous protocol domains to share common access infrastructure including modems, Access Servers, and ISDN routers. RFCs prior to 2341 have specified protocols for supporting IP dial-up via SLIP and multiprotocol dial-up via PPP.

L2F packet structure

Other VPN protocols

• IPsec
• L2TP Layer 2 Tunneling Protocol
• PPTP Point-to-Point Tunneling Protocol

References

External links

• L2F on Cisco.com
• VPDN on Cisco.com
• L2TP on Cisco.com
• RFC2341 on IETF.org
• RFC2341 on RFC Archive