Layer 2 Tunneling Protocol Version 3 is a draft version of L2TP that is proposed as an alternative protocol to MPLS for encapsulation of multiprotocol Layer 2 communications traffic over IP networks. Like L2TP, L2TPv3 provides a ‘pseudo-wire’ service, but scaled to fit carrier requirements. In computer networking, the Layer 2 Tunneling Protocol (L2TP) is a tunneling protocol used to support virtual private networks (VPNs). ... In computer networking and telecommunications, Multiprotocol Label Switching (MPLS) is a data-carrying mechanism, operating at a layer below protocols such as IP. It was designed to provide a unified data-carrying service for both circuit-based clients and packet-switching clients which provide a datagram service model. ... Encapsulation may refer to: (in the vernacular) expressing an idea with few words, such as with an adage, proverb, slogan, or jingle (in software engineering) the use of information hiding within a program (in electronics) the design and manufacture of protective packages for integrated circuit encapsulation (in biomedical engineering) a... The Open Systems Interconnection Reference Model (OSI Model or OSI Reference Model for short) is a layered abstract description for communications and computer network protocol design, developed as part of the Open Systems Interconnect initiative. ... The Internet Protocol (IP) is a data-oriented protocol used by source and destination hosts for communicating data across a packet-switched internetwork. ... In computer networking and telecommunications, a Pseudowire (PW) is an emulation of a native service over a Packet Switched Network (PSN). ...

L2TPv3 can be regarded as being to MPLS what MPLS is to ATM: a simplified version of the same concept, with much of the goodness achieved with a fraction of the effort, at the cost of losing some technical features considered less important in the market. In the case of L2TPv3, the features lost are traffic engineering features considered important in MPLS. The protocol overhead of L2TPv3 is also significantly bigger than MPLS. However, there is no reason why these features could not be re-engineered in or on top of L2TPv3 in later products. Asynchronous Transfer Mode, or ATM for short, is a cell relay network protocol which encodes data traffic into small fixed sized (53 byte; 48 bytes of data and 5 bytes of header information) cells instead of variable sized packets as in packet-switched networks (such as the Internet Protocol or... For another meaning of the term traffic engineering, please see transport traffic engineering. ... For meanings in specific fields, see protocol (computing) or protocol (cryptography). ... In computer science, and moreso in computer programming, overhead is generally considered any combination of excess or indirect computation time, memory, bandwidth, or other resources that are required to be utilized or expended to enable a particular goal. ...

External links

• IETF L2TPEXT working group (http://www.ietf.org/html.charters/l2tpext-charter.html)
• RIPE presentation about L2TPv3 (http://www.ripe.net/ripe/meetings/archive/ripe-42/presentations/ripe42-eof-pseudowires2/)