Editing OSI model (section)

==History==
The development of the OSI model started in the late 1970s to support the emergence of the diverse computer networking methods that were competing for application in the large national networking efforts in the world (see [[OSI protocols]] and [[Protocol Wars]]). In the 1980s, the model became a working product of the Open Systems Interconnection group at the [[International Organization for Standardization]] (ISO). While attempting to provide a comprehensive description of networking, the model failed to garner reliance during the design of the [[Internet]], which is reflected in the less prescriptive [[Internet Protocol Suite]], principally sponsored under the auspices of the [[Internet Engineering Task Force]] (IETF).

In the early- and mid-1970s, networking was largely either government-sponsored ([[NPL network]] in the UK, [[ARPANET]] in the US, [[CYCLADES]] in France) or vendor-developed with proprietary standards, such as [[IBM]]'s [[Systems Network Architecture]] and [[Digital Equipment Corporation]]'s [[DECnet]]. [[Public data network]]s were only just beginning to emerge, and these began to use the [[X.25]] standard in the late 1970s.<ref name=":3" /><ref name=":2">{{cite journal|last1=Roberts|first1=Dr. Lawrence G.|date=November 1978|title=The Evolution of Packet Switching|url=http://www.ece.ucf.edu/~yuksem/teaching/nae/reading/1978-roberts.pdf|journal=IEEE Invited Paper|access-date=February 26, 2022}}</ref>

The [[Packet switching#EPSS|Experimental Packet Switched System]] in the UK {{circa|1973}}–1975 identified the need for defining higher-level protocols.<ref name=":3">{{Cite book|last1=Davies|first1=Howard|url=https://books.google.com/books?id=DN-t8MpZ0-wC&pg=PA3|title=A History of International Research Networking: The People who Made it Happen|last2=Bressan|first2=Beatrice|date=2010-04-26|publisher=John Wiley & Sons|isbn=978-3-527-32710-2|pages=2–3|language=en}}</ref> The UK [[National Computing Centre]] publication, ''Why Distributed Computing'', which came from considerable research into future configurations for computer systems,<ref>{{Cite book|url=https://books.google.com/books?id=fbm7AAAAIAAJ|title=Why distributed computing?: An NCC review of potential and experience in the UK|last1=Down|first1=Peter John|last2=Taylor|first2=Frank Edward|date=1976|publisher=NCC Publications|isbn=9780850121704|language=en}}</ref> resulted in the UK presenting the case for an international standards committee to cover this area at the ISO meeting in [[Sydney]] in March 1977.<ref>{{cite book |last=Radu |first=Roxana |doi=10.1093/oso/9780198833079.003.0003 |chapter=Revisiting the Origins: The Internet and its Early Governance |title=Negotiating Internet Governance |isbn=9780191871405 |date=2019 |pages=43–74 |publisher=Oxford University Press}}</ref><ref name="ieee201703">{{cite magazine|author=Andrew L. Russell|date=30 July 2013|title=OSI: The Internet That Wasn't|url=https://spectrum.ieee.org/osi-the-internet-that-wasnt|magazine=[[IEEE Spectrum]]|volume=50|issue=8}}</ref>

Beginning in 1977, the ISO initiated a program to develop general standards and methods of networking. A similar process evolved at the [[International Telegraph and Telephone Consultative Committee]] (CCITT, from French: ''Comité Consultatif International Téléphonique et Télégraphique''). Both bodies developed documents that defined similar networking models. The British [[Department of Trade and Industry (United Kingdom)|Department of Trade and Industry]] acted as the secretariat, and [[universities in the United Kingdom]] developed [[prototype]]s of the standards.<ref>{{Cite journal |last1=Campbell-Kelly |first1=Martin |last2=Garcia-Swartz |first2=Daniel D |date=2013 |title=The History of the Internet: The Missing Narratives |url=https://papers.ssrn.com/abstract=867087 |journal=Journal of Information Technology |language=en |volume=28 |issue=1 |pages=18–33 |doi=10.1057/jit.2013.4 |ssrn=867087 |s2cid=41013 |issn=0268-3962|url-access=subscription }}</ref>

The OSI model was first defined in raw form in [[Washington, D.C.]], in February 1978 by French software engineer [[Hubert Zimmermann]], and the refined but still draft standard was published by the ISO in 1980.<ref name="ieee201703" />

The drafters of the reference model had to contend with many competing priorities and interests. The rate of technological change made it necessary to define standards that new systems could converge to rather than standardizing procedures after the fact; the reverse of the traditional approach to developing standards.<ref>{{Cite book|last=Sunshine|first=Carl A.|url=https://books.google.com/books?id=Hzj2BwAAQBAJ&pg=PA35|title=Computer Network Architectures and Protocols|publisher=Springer Science & Business Media|year=1989|isbn=978-1-4613-0809-6|pages=35|language=en}}</ref> Although not a standard itself, it was a framework in which future standards could be defined.<ref>{{Cite book|last=Hasman|first=A.|url=https://books.google.com/books?id=u2KyQjiwwTUC&pg=PA251|title=Education and Training in Health Informatics in Europe: State of the Art, Guidelines, Applications|date=1995|publisher=IOS Press|isbn=978-90-5199-234-2|pages=251|language=en}}</ref>

In May 1983,<ref>{{Cite web |title=ISO/OSI (Open Systems Interconnection): 1982 - 1983 {{!}} History of Computer Communications |url=https://historyofcomputercommunications.info/section/11.10/ISO-OSI-(Open-Systems-Interconnection)-1982-1983/ |access-date=2024-07-12 |website=historyofcomputercommunications.info}}</ref> the CCITT and ISO documents were merged to form ''The Basic Reference Model for Open Systems Interconnection'', usually referred to as the ''Open Systems Interconnection Reference Model'', ''OSI Reference Model'', or simply ''OSI model''. It was published in 1984 by both the ISO, as standard ISO 7498, and the renamed CCITT (now called the Telecommunications Standardization Sector of the [[International Telecommunication Union]] or [[ITU-T]]) as standard X.200.

OSI had two major components: an abstract model of networking, called the Basic Reference Model or seven-layer model, and a [[OSI protocols|set of specific protocols]]. The OSI reference model was a major advance in the [[standardisation]] of network concepts. It promoted the idea of a consistent model of protocol layers, defining interoperability between network devices and software.

The concept of a seven-layer model was provided by the work of [[Charles Bachman]] at [[Honeywell Information Systems]].<ref>{{cite web|url=https://history.computer.org/pioneers/bachman.html|author=J. A. N. Lee|title=Computer Pioneers by J. A. N. Lee|publisher=IEEE Computer Society}}</ref> Various aspects of OSI design evolved from experiences with the NPL network, ARPANET, CYCLADES, [[Packet switching#EIN|EIN]], and the [[International Network Working Group]] ([[IFIP]] WG6.1). In this model, a networking system was divided into layers. Within each layer, one or more entities implement its functionality. Each entity interacted directly only with the layer immediately beneath it and provided facilities for use by the layer above it.

The OSI standards documents are available from the ITU-T as the X.200 series of recommendations.<ref>
{{cite web| url = http://www.itu.int/rec/T-REC-X/en| title = ITU-T X-Series Recommendations}}</ref> Some of the protocol specifications were also available as part of the ITU-T X series. The equivalent ISO/IEC standards for the OSI model were available from ISO. Not all are free of charge.<ref>{{cite web|url=http://standards.iso.org/ittf/PubliclyAvailableStandards/index.html |title=Publicly Available Standards |publisher=Standards.iso.org |date=30 July 2010 |access-date=11 September 2010}}</ref>

OSI was an industry effort, attempting to get industry participants to agree on common network standards to provide multi-vendor interoperability.<ref>{{Cite book|url=https://books.google.com/books?id=OVpzAwAAQBAJ&q=Open+Standards+and+the+Digital+Age:+History,+Ideology,+and+Networks|title=Open Standards and the Digital Age: History, Ideology, and Networks|last=Russell|first=Andrew L.|date=2014-04-28|publisher=Cambridge University Press|isbn=978-1-139-91661-5|language=en}}</ref> It was common for large networks to support multiple network protocol suites, with many devices unable to interoperate with other devices because of a lack of common protocols. For a period in the late 1980s and early 1990s, engineers, organizations and nations became [[Protocol Wars|polarized over the issue of which standard]], the OSI model or the [[Internet protocol suite]], would result in the best and most robust computer networks.<ref name="ieee201703" /><ref>{{Cite journal|url=https://courses.cs.duke.edu//common/compsci092/papers/govern/consensus.pdf|title=Rough Consensus and Running Code' and the Internet-OSI Standards War|last=Russell|first=Andrew L.|journal=IEEE Annals of the History of Computing|volume=28|issue=3|date=July–September 2006|pages=48–61|doi=10.1109/MAHC.2006.42}}</ref><ref>{{Cite web|date=2006|title=Standards Wars|url=https://courses.cs.washington.edu/courses/csep590a/06au/projects/standards-wars.pdf}}</ref> However, while OSI developed its networking standards in the late 1980s,<ref>{{Cite book|url=https://books.google.com/books?id=CRMEAAAAMBAJ|title=Network World|date=1988-02-15|publisher=IDG Network World Inc|language=en}}</ref>{{page needed|date=July 2024}}<ref>{{Cite book|url=https://books.google.com/books?id=dBMEAAAAMBAJ&pg=PA50|title=Network World|date=1988-10-10|publisher=IDG Network World Inc|language=en}}</ref>{{page needed|date=July 2024}} [[TCP/IP]] came into widespread use on multi-vendor networks for [[internetworking]].

The OSI model is still used as a reference for teaching and documentation;<ref>{{Cite web|title=The OSI model explained: How to understand (and remember) the 7 layer network model|url=https://www.networkworld.com/article/3239677/the-osi-model-explained-how-to-understand-and-remember-the-7-layer-network-model.html|last=Shaw|first=Keith|date=2018-10-22|website=Network World|language=en|access-date=2020-05-16|archive-date=4 October 2020|archive-url=https://web.archive.org/web/20201004172259/https://www.networkworld.com/article/3239677/the-osi-model-explained-how-to-understand-and-remember-the-7-layer-network-model.html|url-status=dead}}</ref> however, the [[OSI protocols]] originally conceived for the model did not gain popularity. Some engineers argue the OSI reference model is still relevant to [[cloud computing]].<ref>{{Cite web|title=An OSI Model for Cloud|url=https://blogs.cisco.com/cloud/an-osi-model-for-cloud|date=2017-02-24|website=Cisco Blogs|language=en-US|access-date=2020-05-16}}</ref> Others say the original OSI model does not fit today's networking protocols and have suggested instead a simplified approach.<ref>{{Cite web|title=Why it's time to let the OSI model die|url=https://www.networkworld.com/article/2276158/why-it-s-time-to-let-the-osi-model-die.html|last1=Taylor|first1=Steve|last2=Metzler|first2=Jim|date=2008-09-23|website=Network World|language=en|access-date=2020-05-16}}</ref><ref name="Crawford"/>