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 is an extension of the Point-to-Point Tunneling Protocol (PPTP) used by internet service providers (ISPs) to enable endpoints to reside in different machines. L2TP is designed to work with various types of protocols protecting the tunneled data and can even handle data from higher-layer protocols. L2TP uses packet-switched network connections to enable endpoints to reside in different machines. The user has an L2 connection to a LAC, which tunnels individual PPP frames to the NAS. L2TP is often used by ISPs when internet service over, for example, ADSL or.
L2TP was first proposed in 1999 as an upgrade to both L2F and PPTP. It is a more complex protocol to set up when compared to other VPN protocols. L2TP does not work alone, and an additional protocol must supply both security functions. In most cases, Internet Protocol Security (IPSec) provides these data protection services, which is why we commonly use the designation L2TP/IPSec. L2TP employs IPSec for extra security, which offers better data protection than PPTP.
