Pseudowire

{{Short description|A point-to-point connection over a packet-switched network}}

{{Multiple issues|

{{more footnotes|date=October 2014}}

{{context|date=October 2014}}

}}

In computer networking and telecommunications, a pseudowire (or pseudo-wire) is an emulation of a point-to-point connection over a packet-switched network (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 (ATM), Frame Relay, Ethernet or time-division multiplexing (TDM) while the packet network may be Multiprotocol Label Switching (MPLS), Internet Protocol (IPv4 or IPv6), or Layer 2 Tunneling Protocol Version 3 (L2TPv3).

The first pseudowire specifications were the Martini draft for ATM pseudowires, and the TDMoIP draft for transport of E1/T1 over IP.{{Citation|title=Building the Internet of Things with IPv6 and MIPv6|url=https://www.worldcat.org/oclc/851158445|last=Minoli|first=Daniel|date=17 June 2013 |accessdate=2020-02-23|publisher=John Wiley & Sons|isbn= 978-1118647134|oclc=851158445 }}.

In 2001, the Internet Engineering Task Force (IETF) set up the PWE3 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 (ITU) and the MFA Forum, are also active in producing standards and implementation agreements for pseudowires.

Starting from 2006, telecom operators like BellSouth, Supercomm, AT&T, and Verizon began to invest more into pseudowire technology, pointing out its advantages to Ethernet in particular.{{cite web|title=Carriers eye pseudowires for service delivery|url=https://www.lightwaveonline.com/network-design/packet-transport/article/16650043/carriers-eye-pseudowires-for-service-delivery|website=Lightwave|date=January 2006 |accessdate=23 February 2020}} Pseudowires tie services together across multiple transport technologies, including Ethernet over SONET, WDM, GPON, DSL, and WiMax. Over the next decade, the technology became mainstream.

In 2017 Cisco published a comprehensive document explaining the concept, troubleshooting, and configuration details for all Cisco equipment pieces, which supported pseudowire.{{cite web|title=Pseudowire Concepts and troubleshooting|url=https://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/mpls/212007-Pseudowire-Concepts-and-troubleshooting.html|website=Cisco|accessdate=23 February 2020}} Today, the service is provided by a number of telecommunication companies like Axerra Networks, MCI Inc, or by Infrastructure as a service providers like Voxility.{{cite web|title=Axerra Networks|url= https://www.cbinsights.com/company/axerra-networks|website=CBInsights|accessdate=23 February 2020}}

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