L2TP was derived from PPTP features and features of an earlier Cisco protocol called L2F (Layer 2 Forwarding). L2TP supports TACACS+ and RADIUS authentication. PPTP does not. L2TP also supports more protocols than PPTP, including IPX, SNA, and others. Microsoft continues to support PPTP as a tunneling protocol for its Windows products, but L2TP

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. Aug 18, 2011 · Layer 2 Tunneling Protocol (L2TP) is a computer networking protocol used by Internet service providers (ISPs) to enable virtual private network (VPN) operations. L2TP is similar to the Data Link Layer Protocol in the OSI reference model, but it is actually a session layer protocol. A User Datagram Protocol (UDP) port is used for L2TP The Layer 2 Tunneling Protocol (L2TP) is a standard protocol for tunneling L2 traffic over an IP network. Its ability to carry almost any L2 data format over IP or other L3 networks makes it Layer Two Tunneling Protocol (L2TP) is an extension of the Point-to-Point Tunneling Protocol used by an Internet service provider to enable the operation of a virtual private network over the Internet. L2TP merges the best features of two other tunneling protocols: PPTP from Microsoft and L2F from Cisco Systems.

この項目「Layer 2 Tunneling Protocol」は途中まで翻訳されたものです。（原文：en:Layer_2_Tunneling_Protocol 28 September 2009 at 22:11(UTC)） 翻訳作業に協力して下さる方を求めています。

Tunneling protocols like L2TP, GRE, IPSEC and MPLS don't fit well into the OSI model. L2TP tunnels (encapsulates) L2 frames in UDP so it can be transported over layer 3. Metaglossary.com - Definitions for "l2tp"

Layer 2 Tunneling Protocol (L2TP) is a hybrid of PPTP and Layer 2 Forwarding (L2F). It uses the same authentication mechanisms as PPTP but its tunneling protocol is advanced as it relies on IPSec for encryption. Like PPTP, it uses a single point-to-point connection per session.

M Series,MX Series. L2TP is defined in RFC 2661, Layer Two Tunneling Protocol (L2TP). Sep 24, 2008 · Documented in RFC2661, L2TP and RFC3931, L2TPv3 are protocols for tunneling network traffic between two peers over an existing network.. A device running affected 12.2 and 12.4 versions of Cisco IOS and that has the L2TP mgmt daemon process running will reload when processing a specially crafted L2TP packet.