Layer 2 Tunneling Protocol In computer networking, Layer 2
Tunneling Protocol (L2TP) is a tunneling protocol used to
support virtual private networks (VPNs) or as part of the
delivery of services by ISPs. It does not provide any encryption
or confidentiality by itself; it relies on an encryption
protocol that it passes within the tunnel to provide privacy.
|Internet protocol suite| Published in 1999 as proposed standard
RFC 2661, L2TP has its origins primarily in two older tunneling
protocols for Point-to-Point communication: Cisco's Layer 2
Forwarding Protocol (L2F) and USRobotics Point-to-Point
Tunneling Protocol (PPTP). A new version of this protocol,
L2TPv3, was published as proposed standard RFC 3931 in 2005.
L2TPv3 provides additional security features, improved
encapsulation, and the ability to carry data links other than
simply PPP (PPP) over an IP network (e.g., Frame Relay,
Ethernet, ATM, etc.). The entire L2TP packet, including payload
and L2TP header, is sent within a User Datagram Protocol (UDP)