L2F Fullform

L2F or Layer 2 Forwarding is a tunneling protocol developed by Cisco Systems. It is used to build virtual private networks (VPNs) over the internet that could in turn provide the facility of transporting secure data packets. It is mainly used for tunneling of traffic generated by Point-to-Point Protocol (PPP) i.e. it is used to forward PPP packets from the client to the remote node. It creates a secure end-to-end tunnel between the Internet Service Provider (ISP) and the enterprise customers.L2F protocol is a part of the Layer 2 Tunneling Protocol (L2TP).


  • L2F is isolated from the details of the media i.e. it provides abstraction facilities over which the tunnel is established.
  • L2F provides a tunnel which is packet-oriented and consists of point-to-point connectivity.
  • L2F carries uninterpreted frames that allow it to operate on the features without having a clear understanding of these features.
  • L2F is compatible with Password Authentication Protocol (PAP) and Challenge-Handshake Authentication Protocol (CHAP).
  • L2F is compatible with Apple’s AppleTalk Remote Access Protocol (ARAP).
  • L2F’s packet format is inspired by Generic Routing Encapsulation (GRE)


  • It creates an end to end tunnel that ensures data encapsulation and safe transmission.
  • L2F protocol is more secure because it can be used with other security protocols flawlessly.
  • L2F can provide user authentication through Remote Authentication Dial-In User Service (RADIUS), dynamic allocation of addresses, and quality of service (QoS) on the server-side.
  • L2F tunnels can support multiple connections.


  • L2F does not provide encryption facilities and relies on the protocol being tunneled to provide privacy.
  • L2F does not provide flow control of data.
  • L2F does not provide Attribute-value (AV) pair hiding.

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