International Network Working Group

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The International Network Working Group (INWG) was a group of prominent computer science researchers in the 1970s who studied and developed standards and protocols for computer networking. Set up in 1972 as an informal group to consider the technical issues involved in connecting different networks, its goal was to develop international standard protocols for internetworking. INWG became a subcommittee of the International Federation for Information Processing (IFIP) two years later. Concepts developed by members of the group contributed to the original "Protocol for Packet Network Intercommunication" proposed by Vint Cerf and Bob Kahn in 1974 and the Transmission Control Protocol and Internet Protocol (TCP/IP) that emerged later.


Founding and IFIP affiliation[edit]

The International Network Working Group was formed by Steve Crocker, Louis Pouzin, Donald Davies, and Peter Kirstein in June 1972 in Paris at a networking conference organised by Pouzin.[1][2] Crocker saw that it would be useful to have an international version of the "Network Working Group", which developed the Network Control Program for the ARPANET.[3]

At the International Conference on Computer Communication (ICCC) in Washington D.C. in October 1972, Vint Cerf was approved as INWG's Chair on Steve Crocker's recommendation (Crocker also allocated him $50k funding for the role). Active members included Cerf, Alex McKenzie, Donald Davies, Roger Scantlebury, Louis Pouzin and Hubert Zimmermann.[4][5][6] These researchers represented the American ARPANET,[nb 1] the French CYCLADES project,[nb 2] and the British team working on the NPL network, EPSS, and European Informatics Network.[4]

In January 1974, Pouzin arranged affiliation with the International Federation for Information Processing (IFIP).[7] INWG became IFIP Working Group 1 under Technical Committee 6 (Data Communication) with the title "International Packet Switching for Computer Sharing" (WG6.1). This standing, although informal, enabled the group to provide technical input on packet networking to CCITT and ISO.[4][6][8][9][10] Its purpose was to study and develop "international standard protocols for internetworking".[7]

Proposal for an international end-to-end protocol[edit]

INWG met in Stanford in June 1973 and there was a follow-up meeting in July. Zimmermann and Metcalfe dominated the discussions.[11][12][13] Notes from the meetings were recorded by Cerf and Alex McKenzie, from BBN, and published as numbered INWG Notes (some of which were also RfCs).

In September 1973, Cerf and Bob Kahn (who was not a member of INWG) gave a paper at an INWG meeting at the University of Sussex in England.[14] Their ideas were refined further in long discussions with Davies, Scantlebury, Pouzin and Zimmerman.[15] Louis Pouzin introduced the term catenet, the original term for an interconnected network, in October 1973.[4][16]

Zimmerman wrote a paper "Standard host-host protocol for heterogeneous computer networks" in April 1974,[17] and Pouzin published a May 1974 paper "A Proposal for Interconnecting Packet Switching Networks".[18] Kahn and Vint Cerf also published their proposal in May 1974, "A Protocol for Packet Network Intercommunication", which introduced the term internet as a shorthand for internetwork. The paper acknowledged several members of the INWG.[19]

The Internet architecture as seen by the INWG.[20]

Over three years, the group shared numerous numbered Notes. There were two competing proposals,[21] INWG 39 based on the early Transmission Control Program proposed by Kahn and Cerf (updated in INWG 72),[22] and INWG 61 based on the CYCLADES TS (transport station) protocol proposed by Pouzin and Zimmermann. There were two sticking points: how fragmentation should work; and whether the data flow was an undifferentiated stream or maintained the integrity of the units sent. These were not major differences and after "hot debate" a synthesis was proposed in INWG 96.[4][23][20][24]

This protocol, agreed by the group in 1975, titled "Proposal for an international end to end protocol", was written by Vint Cerf, Alex McKenzie, Roger Scantlebury, and Hubert Zimmermann.[25][26][27] It was presented to the CCITT in 1976 by Derek Barber, who became INWG chair earlier that year. Although the protocol was adopted by networks in Europe,[28] it was not adopted by the CCITT nor by the ARPANET.

CCITT went on to adopt the X.25 standard in 1976, based on virtual circuits, and ARPA ultimately developed the Internet protocol suite, including the Internet Protocol as connectionless layer and the Transmission Control Protocol as a reliable connection-oriented service, which incorporated concepts from Louis Pouzin's CYCLADES project.[29]


The idea for a router (called gateway at the time) initially came about through INWG. These gateway devices were different from most previous packet switching schemes in two ways. First, they connected dissimilar kinds of networks, such as serial lines and local area networks. Second, they were connectionless devices, which had no role in assuring that traffic was delivered reliably, leaving that function entirely to the hosts. This particular idea, the end-to-end principle, had been pioneered in the CYCLADES network.[30]


Alex McKenzie served as chair from 1979-1982 and Secretary beginning in 1983.[7] Later international work led to the OSI model in 1984, of which many members of the INWG became advocates.[5] During the 'Protocol Wars' of the late 1980s and early 1990s, engineers, organizations and nations became 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. ARPA partnerships with the telecommunication and computer industry led to widespread private sector adoption of the Internet protocol suite as a communication protocol.[5][31][32]

The INWG continued to work on protocol design and formal specification until the 1990s when it disbanded as the Internet grew rapidly.[4] Nonetheless, issues with the Internet Protocol suite remain and alternatives have been proposed building on INWG ideas such as Recursive Internetwork Architecture.[20]


The group had about 100 members, including the following:[4][9]

  • D. Barber
  • B. Barker
  • V. Cerf
  • W. Clipsham
  • D. Davies
  • R. Despres
  • V. Detwiler
  • F. Heart
  • A. McKenzie
  • L. Pouzin
  • O. Riml
  • K. Samuelson
  • K. Sandum
  • R. Scantlebury
  • B. Sexton
  • P. Shanks
  • C.D. Shepard
  • J. Tucker
  • B. Wessler
  • H. Zimmerman

See also[edit]


  1. ^ Specifically, McKenzie represented BBN and Cerf represented Stanford University.
  2. ^ Remi Despres, who represented the French RCP, was also a member.


  1. ^ Pelkey, James. "8.3 CYCLADES Network and Louis Pouzin 1971–1972". Entrepreneurial Capitalism and Innovation: A History of Computer Communications 1968–1988.
  2. ^ Hafner & Lyon 1999, p. 222
  3. ^ "Internet founders say flexible framework was key to explosive growth". Princeton University. Retrieved 2020-02-07.
  4. ^ a b c d e f g McKenzie, Alexander (2011). "INWG and the Conception of the Internet: An Eyewitness Account". IEEE Annals of the History of Computing. 33 (1): 66–71. doi:10.1109/MAHC.2011.9. ISSN 1934-1547. S2CID 206443072.
  5. ^ a b c Andrew L. Russell (30 July 2013). "OSI: The Internet That Wasn't". IEEE Spectrum. Vol. 50, no. 8.
  6. ^ a b Abbate, Janet (2000). Inventing the Internet. MIT Press. pp. 123–4. ISBN 978-0-262-51115-5.
  7. ^ a b c "Collection: Alex McKenzie collection of computer networking development records | University of Minnesota Archival Collections Guides". Retrieved 2023-01-27.
  8. ^ The "Hidden" Prehistory of European Research Networking. Trafford Publishing. ISBN 978-1-4669-3935-6.
  9. ^ a b Davies, Donald Watts (1979). Computer networks and their protocols. Internet Archive. Chichester, [Eng.] ; New York : Wiley. p. 466. ISBN 9780471997504.
  10. ^ "Vinton Cerf : How the Internet Came to Be". Retrieved 2021-12-22.
  11. ^ Isaacson, Walter (2014). The innovators : how a group of hackers, geniuses, and geeks created the digital revolution. Internet Archive. New York : Simon & Schuster. ISBN 978-1-4767-0869-0.
  12. ^ Pelkey, James. "8.4 Transmission Control Protocol (TCP) 1973-1976". Entrepreneurial Capitalism and Innovation: A History of Computer Communications 1968–1988.
  13. ^ Taylor, Bob (October 11, 2008), "Oral History of Robert (Bob) W. Taylor" (PDF), Computer History Museum Archive, CHM Reference number: X5059.2009: 28
  14. ^ Pelkey, James. "8.4 Transmission Control Protocol (TCP) 1973-1976". Entrepreneurial Capitalism and Innovation: A History of Computer Communications 1968–1988.
  15. ^ Hafner, Katie; Lyon, Matthew (1999-08-19) [1996]. Where Wizards Stay Up Late: The Origins Of The Internet. Simon and Schuster. pp. 225–6. ISBN 978-0-684-87216-2.
  16. ^ Vint Cerf (July 1978). "IEN 48: The Catenet Model for Internetworking". IETF. The term "catenet" was introduced by L. Pouzin in 1974.
  17. ^ Pouzin, Louis (1975-05-19). "An integrated approach to network protocols". Proceedings of the May 19-22, 1975, national computer conference and exposition. AFIPS '75. New York, NY, USA: Association for Computing Machinery: 701–707. doi:10.1145/1499949.1500100. ISBN 978-1-4503-7919-9.
  18. ^ A Proposal for Interconnecting Packet Switching Networks, L. Pouzin, Proceedings of EUROCOMP, Brunel University, May 1974, pp. 1023-36.
  19. ^ Cerf, V.; Kahn, R. (1974). "A Protocol for Packet Network Intercommunication" (PDF). IEEE Transactions on Communications. 22 (5): 637–648. doi:10.1109/TCOM.1974.1092259. ISSN 1558-0857. The authors wish to thank a number of colleagues for helpful comments during early discussions of international network protocols, especially R. Metcalfe, R. Scantlebury, D. Walden, and H. Zimmerman; D. Davies and L. Pouzin who constructively commented on the fragmentation and accounting issues; and S. Crocker who commented on the creation and destruction of associations.
  20. ^ a b c J. Day. How in the Heck Do You Lose a Layer!? 2nd IFIP International Conference of the Network of the Future, Paris, France, 2011
  21. ^ Russell, Andrew L. (2014). Open standards and the digital age: history, ideology, and networks. New York: Cambridge Univ Press. p. 196. ISBN 978-1107039193.
  22. ^ Specification of Internet Transmission Control Program. 1974. doi:10.17487/RFC0675. RFC 675.
  23. ^ Russell, Andrew L.; Schafer, Valérie (2014). "In the Shadow of ARPANET and Internet: Louis Pouzin and the Cyclades Network in the 1970s". Technology and Culture. 55 (4): 893–894. ISSN 0040-165X.
  24. ^ Day, John (2007-12-27). Patterns in Network Architecture: A Return to Fundamentals (paperback): A Return to Fundamentals. Pearson Education. ISBN 978-0-13-270456-4.
  25. ^ Cerf, V.; McKenzie, A; Scantlebury, R; Zimmermann, H (1976). "Proposal for an international end to end protocol". ACM SIGCOMM Computer Communication Review. 6: 63–89. doi:10.1145/1015828.1015832. S2CID 36954091.
  26. ^ Davies, Donald Watts (1979). Computer Networks and Their Protocols. Wiley. p. 468. ISBN 978-0-471-99750-4.
  27. ^ Esmailzadeh, Riaz (2016-03-04). Broadband Telecommunications Technologies and Management. John Wiley & Sons. ISBN 978-1-118-99565-5.
  28. ^ "Hubert Zimmerman". Retrieved 2020-08-27.
  29. ^ "The internet's fifth man". Economist. 13 December 2013. Retrieved 11 September 2017. In the early 1970s Mr Pouzin created an innovative data network that linked locations in France, Italy and Britain. Its simplicity and efficiency pointed the way to a network that could connect not just dozens of machines, but millions of them. It captured the imagination of Dr Cerf and Dr Kahn, who included aspects of its design in the protocols that now power the internet.
  30. ^ Bennett, Richard (September 2009). "Designed for Change: End-to-End Arguments, Internet Innovation, and the Net Neutrality Debate" (PDF). Information Technology and Innovation Foundation. pp. 7, 11. Retrieved 11 September 2017.
  31. ^ Russell, Andrew L. "Rough Consensus and Running Code' and the Internet-OSI Standards War" (PDF). IEEE Annals of the History of Computing.
  32. ^ Davies, Howard; Bressan, Beatrice (2010-04-26). A History of International Research Networking: The People who Made it Happen. John Wiley & Sons. ISBN 978-3-527-32710-2.

Further reading[edit]

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