Overview of IPSec and L2TP Technologies - Page 7
L2TP
Layer 2 Tunneling Protocol (L2TP) provides a means for tunneling IP traffic at layer 2
and is derived from two other tunneling protocols (PPTP and L2F). L2TP is built upon
the well-established Internet communications protocol Point-to-Point Protocol (PPP),
and Transmission Control Protocol/Internet Protocol (TCP/IP).
L2TP tunneling encapsulates IP data packets in PPP, for transmission through an IP
network. Upon receipt, the IP and PPP headers are stripped away, exposing the
original IP data packet. In this way encapsulation allows the transportation of IP
packets over a PPP authenticated connection.
The diagram below demonstrates the two modes of tunneling that an L2TP tunnel may
operate.
Figure 3. LT2P Tunneling Modes
IP Office (R3.0) Virtual Private Networking
Overview of IPSec and L2TP Technologies - Page 7
40DHB0002UKER Issue 3 (4th February 2005)
General
