computer networking A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or b ...

and

telecommunications Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of ...

, a pseudowire (or pseudo-wire) is an emulation of a point-to-point connection over a

packet-switched network In telecommunications, packet switching is a method of grouping data into short messages in fixed format, i.e. '' packets,'' that are transmitted over a digital network. Packets consist of a header and a payload. Data in the header is used b ...

(PSN). The pseudowire emulates the operation of a "transparent wire" carrying the service, but it is realized that this emulation will rarely be perfect. The service being carried over the "wire" may be

Asynchronous Transfer Mode Asynchronous Transfer Mode (ATM) is a telecommunications standard defined by the American National Standards Institute and International Telecommunication Union Telecommunication Standardization Sector (ITU-T, formerly CCITT) for digital trans ...

(ATM),

Frame Relay Frame Relay (FR) is a standardized wide area network (WAN) technology that specifies the Physical layer, physical and data link layers of digital telecommunications channels using a packet switching methodology. Frame Relay was originally devel ...

Ethernet Ethernet ( ) is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...

or time-division multiplexing (TDM) while the packet network may be

Multiprotocol Label Switching Multiprotocol Label Switching (MPLS) is a routing technique in telecommunications networks that directs data from one node to the next based on labels rather than network addresses. Whereas network addresses identify endpoints, the labels iden ...

(MPLS),

Internet Protocol The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet. IP ...

(

IPv4 Internet Protocol version 4 (IPv4) is the first version of the Internet Protocol (IP) as a standalone specification. It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. ...

IPv6 Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communication protocol, communications protocol that provides an identification and location system for computers on networks and routes traffic ...

), or Layer 2 Tunneling Protocol Version 3 (L2TPv3). The first pseudowire specifications were the

Martini draft Martini may refer to: * Martini (cocktail), a drink made with gin and vermouth, garnished with an olive or a lemon twist * Martini (vermouth), a brand of vermouth * Martini (surname), an Italian surname * Martini (automobile company), a Swiss auto ...

for ATM pseudowires, and the

TDMoIP In computer networking and telecommunications, TDM over IP (TDMoIP) is the emulation of time-division multiplexing (TDM) over a packet-switched network (PSN). TDM refers to a T1, E1, T3 or E3 signal, while the PSN is based either on IP or M ...

draft for transport of E1/T1 over IP. In 2001, the

Internet Engineering Task Force The Internet Engineering Task Force (IETF) is a standards organization for the Internet standard, Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster ...

(IETF) set up the

PWE3 In 2001, the IETF set up the Pseudowire Emulation Edge to Edge working group, and this group was given the initialism PWE3 (the ''3'' standing for the third power of ''E'', i.e. ''EEE''). The working group was chartered to develop an architecture ...

working group, which was chartered to develop an architecture for service provider edge-to-edge pseudowires, and service-specific documents detailing the encapsulation techniques. Other standardization forums, including the

International Telecommunication Union The International Telecommunication Union (ITU)In the other common languages of the ITU: * * is a list of specialized agencies of the United Nations, specialized agency of the United Nations responsible for many matters related to information ...

(ITU) and the MFA Forum, are also active in producing standards and implementation agreements for pseudowires. Starting from 2006, telecom operators like

BellSouth BellSouth, LLC (stylized as ''BELLSOUTH'' and formerly known as BellSouth Corporation) was an American telecommunications holding company based in Atlanta, Georgia. BellSouth was one of the seven original Regional Bell Operating Companies after ...

, Supercomm,

AT&T AT&T Inc., an abbreviation for its predecessor's former name, the American Telephone and Telegraph Company, is an American multinational telecommunications holding company headquartered at Whitacre Tower in Downtown Dallas, Texas. It is the w ...

, and

Verizon Verizon Communications Inc. ( ), is an American telecommunications company headquartered in New York City. It is the world's second-largest telecommunications company by revenue and its mobile network is the largest wireless carrier in the ...

began to invest more into pseudowire technology, pointing out its advantages to Ethernet in particular. Pseudowires tie services together across multiple transport technologies, including

Ethernet over SONET Ethernet Over SDH (EoS or EoSDH) or Ethernet over SONET refers to a set of protocols which allow Ethernet traffic to be carried over synchronous digital hierarchy networks in an efficient and flexible way. The same functions are available using SONE ...

, WDM,

GPON ITU-T G.984 is the series of standards for implementing a gigabit-capable passive optical network (GPON). It is commonly used to implement the link to the customer (the ''last kilometre'', or ''last mile'') of fibre-to-the-premises ( FTTP) serv ...

DSL Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric di ...

, and

WiMax Worldwide Interoperability for Microwave Access (WiMAX) is a family of wireless broadband communication standards based on the IEEE 802.16 set of standards, which provide physical layer (PHY) and media access control (MAC) options. The WiMA ...

. Over the next decade, the technology became mainstream. In 2017

Cisco Cisco Systems, Inc. (using the trademark Cisco) is an American multinational digital communications technology conglomerate corporation headquartered in San Jose, California. Cisco develops, manufactures, and sells networking hardware, s ...

published a comprehensive document explaining the concept, troubleshooting, and configuration details for all Cisco equipment pieces, which supported pseudowire. Today, the service is provided by a number of telecommunication companies like Axerra Networks,

MCI Inc MCI, Inc. (formerly WorldCom and MCI WorldCom) was a telecommunications company. For a time, it was the second-largest long-distance telephone company in the United States, after AT&T. WorldCom grew largely by acquiring other telecommunicatio ...

, or by

Infrastructure as a service Infrastructure as a service (IaaS) is a cloud computing service model where a cloud services vendor provides computing resources such as storage, network, servers, and virtualization (which emulates computer hardware). This service frees users fr ...

providers like Voxility. There are now many pseudowire standards, the most important of which are IETF RFCs as well as ITU-T Recommendations:

RFCs

* Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture. * Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for Use over an MPLS PSN * Encapsulation Methods for Transport of Ethernet over MPLS Networks * Pseudowire Setup and Maintenance - Using the

Label Distribution Protocol Label Distribution Protocol (LDP) is a protocol in which routers capable of Multiprotocol Label Switching (MPLS) exchange label mapping information. Two routers with an established session are called LDP peers and the exchange of information is bi ...

(LDP) * Structure-Agnostic Time Division Multiplexing (TDM) over Packet (SAToP) * Pseudowire Emulation Edge-to-Edge (PWE3) Fragmentation and Reassembly * Encapsulation Methods for Transport of PPP/High-Level Data Link Control (HDLC) over MPLS Networks * Encapsulation Methods for Transport of Frame Relay over Multiprotocol Label Switching (MPLS) Networks * Pseudowire Emulation Edge-to-Edge (PWE3) Frame Check Sequence Retention * Encapsulation Methods for Transport of Asynchronous Transfer Mode (ATM) over MPLS Networks * Pseudowire Emulation Edge-to-Edge (PWE3) Asynchronous Transfer Mode (ATM) Transparent Cell Transport Service * Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) Circuit Emulation over Packet (CEP) * Time Division Multiplexing over IP (TDMoIP) * Structure-Aware Time Division Multiplexed (TDM) Circuit Emulation Service over Packet Switched Network (CESoPSN) * Pseudowire Virtual Circuit Connectivity Verification (VCCV): A Control Channel for Pseudowires * Control Protocol Extensions for the Setup of Time-Division Multiplexing (TDM) Pseudowires in MPLS Networks

ITU-T Recommendations

*Y.1411 ATM pseudowires *Y.1412 AAL5 pseudowires *Y.1413 TDM pseudowires *Y.1414 Voice Services pseudowires *Y.1415 Ethernet pseudowires *Y.1418 Pseudowire Layer Networks *Y.1452 Voice Services over IP *Y.1453 TDM over IP *X.84 Frame Relay pseudowires

References

{{Reflist

External links

Pseudowire Emulation Edge to Edge
Network architecture Tunneling protocols

RFCs

ITU-T Recommendations

See also

References

External links