Based on designs first conceived by Donald Davies in 1965, development work began in 1966. Construction began in 1968 and elements of the first version of the network, the Mark I, became operational in early 1969 then fully operational in January 1970. The Mark II version operated from 1973 until 1986. The NPL network was the first computer network to implement packet switching and NPL was the first to use high-speed links. Its original design, along with the innovations implemented in the ARPANET and the CYCLADES network, laid down the technical foundations of the modern Internet.
NPL network packet
In 1965, Donald Davies, who was later appointed to head of the NPL Division of Computer Science, proposed a commercial national data network in the United Kingdom based on packet switching in Proposal for the Development of a National Communications Service for On-line Data Processing.[1][2] The following year, he refined his ideas in Proposal for the Development of a National Communications Service for OnLine Data Processing.[3][4] The design was the first to describe the concept of an "interface computer", today known as a router.[5]
A written version of the proposal entitled A digital communications network for computers giving rapid response at remote terminals was presented by Roger Scantlebury at the Symposium on Operating Systems Principles in 1967. The design involved transmitting signals (packets) across a network with a hierarchical structure. It was proposed that "local networks" be constructed with interface computers which had responsibility for multiplexing among a number of user systems (time-sharing computers and other users) and for communicating with "high level network". The latter would be constructed with "switching nodes" connected together with megabit rate circuits (T1 links, which run with a 1.544 Mbit/s line rate).[6][7][8][9] In Scantlebury's report following the conference, he noted "It would appear that the ideas in the NPL paper at the moment are more advanced than any proposed in the USA".[10][11][12]
Packet switching
The first theoretical foundation of packet switching was the work of Paul Baran, at RAND, in which data was transmitted in small chunks and routed independently by a method similar to store-and-forward techniques between intermediate networking nodes.[13][14][15] Davies independently arrived at the same model in 1965 and named it packet switching.[16] He chose the term "packet" after consulting with an NPL linguist because it was capable of being translated into languages other than English without compromise.[17] In July 1968, NPL put on a demonstration of real and simulated networks at an event organised by the Real Time Club at the Royal Festival Hall in London.[18] Davies gave the first public presentation of packet switching on 5 August 1968 at the IFIP Congress in Edinburgh.[19]
Davies' original ideas influenced other research around the world.[7][20][21]Larry Roberts incorporated these concepts into the design for the ARPANET.[22][23][24] The NPL network initially proposed a line speed of 768 kbit/s.[25] Influenced by this, the planned line speed for ARPANET was upgraded from 2.4kbit/s to 50kbit/s and a similar packet format adopted.[26][27]Louis Pouzin'sCYCLADES project in France was also influenced by Davies' work.[28] These networks laid down the technical foundations of the modern Internet.
Network development
Beginning in late 1966,[29] Davies' tasked Derek Barber, his deputy, to establish a team to build a local-area network to serve the needs of NPL and prove the feasibility of packet switching. The team consisted of:[18][29][30][31][32][33]
Software: Peter Wilkinson (lead), John Laws, Carol Walsh, Keith Wilkinson (no relation) and Rex Haymes.
Hardware: Keith Bartlett (lead), Les Pink, Patrick Woodroffe, Brian Aldous, Peter Carter, Peter Neale and a few others.
The team worked through 1967 to produce design concepts for a wide-area network and a local-area network to demonstrate the technology. Construction of the local-area network began in 1968 using a Honeywell 516 node.[34][35] The NPL team liaised with Honeywell in the adaptation of the DDP516 input/output controller,[29] and, the following year, the ARPANET chose the same computer to serve as Interface Message Processors (IMPs).[36]
Elements of the first version of the network, Mark I NPL Network, became operational in early 1969 (before the ARPANET installed its first node).[7][37][38][39] The network was fully operational in January 1970.[7] The local-area NPL network followed by the wide-area ARPANET in the United States were the first two computer networks that implemented packet switching.[40][41] The network used high-speed links, the first computer network to do so.[42][30][43]
In 1976, 12 computers and 75 terminal devices were attached,[44] and more were added. The network remained in operation until 1986.[34]
Protocol development
NPL network model
The first use of the term protocol in a modern data-commutations context occurs in a memorandum entitled A Protocol for Use in the NPL Data Communications Network written by Roger Scantlebury and Keith Bartlett in April 1967.[30][45][46][47] A further publication by Bartlett in 1968 introduced the concept of an alternating bit protocol (later used by the ARPANET and the EIN)[48][49] and described the need for three levels of data transmission,[50] roughly corresponding to the lower levels of the seven-layer OSI model that emerged a decade later.
The Mark II version, which operated from 1973, used such a "layered" protocol architecture.[7][51]
The NPL team also introduced the idea of protocol verification.[30] Protocol verification was discussed in the November 1978 special edition of the Proceedings of the IEEE on packet switching.[52]
Simulation studies
The NPL team also carried out simulation work on the performance of wide-area packet networks, studying datagrams and network congestion. This work was carried out to investigate networks of a size capable of providing data communications facilities to most of the U.K.[7][28][53][54][55]
Barber was appointed director of the European COST 11 project and played a leading part in the European Informatics Network (EIN).[64] Scantlebury led the UK technical contribution, reporting directly to Donald Davies.[30][60][65][66] The EIN protocol helped to launch the INWG and X.25 protocols.[49][67][68] INWG proposed an international end to end protocol in 1975/6,[69] although this was not widely adopted.[70][71] Barber became the chair of INWG in 1976.[60] He proposed and implemented a mail protocol for EIN.[72]
NPL investigated the "basic dilemma" involved in internetworking; that is, a common host protocol would require restructuring existing networks if they were not designed to use the same protocol. NPL connected with the European Informatics Network by translating between two different host protocols while the NPL connection to the Post Office Experimental Packet Switched Service used a common host protocol in both networks. This work confirmed establishing a common host protocol would be more reliable and efficient.[73]
Davies and Barber published Communication networks for computers in 1973 and Computer networks and their protocols in 1979.[74][75][76] They spoke at the Data Communications Symposium in 1975 about the "battle for access standards" between datagrams and virtual circuits, with Barber saying the "lack of standard access interfaces for emerging public packet-switched communication networks is creating 'some kind of monster' for users".[77] For a long period of time, the network engineering community was polarized over the implementation of competing protocol suites, commonly known as the Protocol Wars. It was unclear which type of protocol would result in the best and most robust computer networks.[78]
Email
Derek Barber proposed an electronic mail protocol in 1979 in INWG 192 and implemented it on the EIN.[79] This was referenced by Jon Postel in his early work on Internet email, published in the Internet Experiment Note series.[80]
Network security
Davies' later research at NPL focused on data security for computer networks.[81]
The concepts of packet switching, high-speed routers, layered communication protocols, hierarchical computer networks, and the essence of the end-to-end principle that were researched and developed at the NPL became fundamental to data communication in modern computer networks including the Internet.[82][83][84][85][86]
Beyond NPL, and the designs of Paul Baran at RAND, DARPA was the most important institutional force, creating the ARPANET, the first wide-area packet-switched network, to which many other network designs at the time were compared or replicated.[87] The ARPANET's routing, flow control, software design and network control were developed independently by the IMP team working for Bolt Beranek & Newman.[88][89] The CYCLADES network designed by Louis Pouzin at the IRIA in France built on the work of Donald Davies and pioneered important improvements to the ARPANET design.[90][91]
Moreover, in the view of some, the research and development of internetworking,[92] and TCP/IP in particular (which was sponsored by DARPA), marks the true beginnings of the Internet.[36][93][94] The adoption of TCP/IP and the early governance of the Internet were also fostered by DARPA.
Edmondson-Yurkanan, Chris (2007). "SIGCOMM's archaeological journey into networking's past". Communications of the ACM. 50 (5): 63–68. doi:10.1145/1230819.1230840. ISSN0001-0782. In his first draft dated Nov. 10, 1965 [5], Davies forecast today's "killer app" for his new communication service: "The greatest traffic could only come if the public used this means for everyday purposes such as shopping... People sending enquiries and placing orders for goods of all kinds will make up a large section of the traffic... Business use of the telephone may be reduced by the growth of the kind of service we contemplate."
Pelkey, James (2007), "NPL Network and Donald Davies 1966 - 1971", Entrepreneurial Capitalism and Innovation: A History of Computer Communications 1968-1988, retrieved 13 April 2016
Roberts, Dr. Lawrence G. (May 1995). "The ARPANET & Computer Networks". Archived from the original on 24 March 2016. Retrieved 13 April 2016. Then in June 1966, Davies wrote a second internal paper, "Proposal for a Digital Communication Network" In which he coined the word packet,- a small sub part of the message the user wants to send, and also introduced the concept of an "Interface computer" to sit between the user equipment and the packet network.
"Oral-History:Donald Davies & Derek Barber". Retrieved 13 April 2016. the ARPA network is being implemented using existing telegraphic techniques simply because the type of network we describe does not exist. It appears that the ideas in the NPL paper at this moment are more advanced than any proposed in the USA
Naughton, John (2015). "8 Packet post". A Brief History of the Future: The origins of the Internet. Hachette UK. ISBN978-1474602778. they lacked one vital ingredient. Since none of them had heard of Paul Baran they had no serious idea of how to make the system work. And it took an English outfit to tell them.
Barber, Derek (Spring 1993). "The Origins of Packet Switching". The Bulletin of the Computer Conservation Society (5). ISSN0958-7403. Retrieved 6 September 2017. Roger actually convinced Larry that what he was talking about was all wrong and that the way that NPL were proposing to do it was right. I've got some notes that say that first Larry was sceptical but several of the others there sided with Roger and eventually Larry was overwhelmed by the numbers.
Barber, Derek (Spring 1993). "The Origins of Packet Switching". The Bulletin of the Computer Conservation Society (5). ISSN0958-7403. Retrieved 6 September 2017. There had been a paper written by [Paul Baran] from the Rand Corporation which, in a sense, foreshadowed packet switching in a way for speech networks and voice networks
"On packet switching". Net History. Retrieved 8 January 2024. [Scantlebury said] Clearly Donald and Paul Baran had independently come to a similar idea albeit for different purposes. Paul for a survivable voice/telex network, ours for a high-speed computer network.
Roberts, Dr. Lawrence G. (November 1978). "The Evolution of Packet Switching"(PDF). IEEE Invited Paper. Retrieved 10 September 2017. In nearly all respects, Davies' original proposal, developed in late 1965, was similar to the actual networks being built today.
"Computer Pioneers - Donald W. Davies". IEEE Computer Society. Retrieved 20 February 2020. In 1965, Davies pioneered new concepts for computer communications in a form to which he gave the name "packet switching." ... The design of the ARPA network (ArpaNet) was entirely changed to adopt this technique.; "A Flaw In The Design". The Washington Post. 30 May 2015. The Internet was born of a big idea: Messages could be chopped into chunks, sent through a network in a series of transmissions, then reassembled by destination computers quickly and efficiently. Historians credit seminal insights to Welsh scientist Donald W. Davies and American engineer Paul Baran. ... The most important institutional force ... was the Pentagon's Advanced Research Projects Agency (ARPA) ... as ARPA began work on a groundbreaking computer network, the agency recruited scientists affiliated with the nation's top universities.
F.E. Froehlich, A. Kent (1990). The Froehlich/Kent Encyclopedia of Telecommunications: Volume 1 - Access Charges in the U.S.A. to Basics of Digital Communications. CRC Press. p.344. ISBN0824729005. Although there was considerable technical interchange between the NPL group and those who designed and implemented the ARPANET, the NPL Data Network effort appears to have had little fundamental impact on the design of ARPANET. Such major aspects of the NPL Data Network design as the standard network interface, the routing algorithm, and the software structure of the switching node were largely ignored by the ARPANET designers. There is no doubt, however, that in many less fundamental ways the NPL Data Network had and effect on the design and evolution of the ARPANET.
Campbell-Kelly, Martin (1987). "Data Communications at the National Physical Laboratory (1965-1975)". Annals of the History of Computing. 9 (3/4): 221–247. doi:10.1109/MAHC.1987.10023. S2CID8172150. the first occurrence in print of the term protocol in a data communications context ... the next hardware tasks were the detailed design of the interface between the terminal devices and the switching computer, and the arrangements to secure reliable transmission of packets of data over the high-speed lines
Rayner, David; Barber, Derek; Scantlebury, Roger; Wilkinson, Peter (2001). NPL, Packet Switching and the Internet. Symposium of the Institution of Analysts & Programmers 2001. Archived from the original on 7 August 2003. Retrieved 13 June 2024. The system first went 'live' early in 1969
Haughney Dare-Bryan, Christine (22 June 2023). Computer Freaks (Podcast). Chapter Two: In the Air. Inc. Magazine. 35:55 minutes in. Leonard Kleinrock: Donald Davies ... did make a single node packet switch before ARPA did
John S, Quarterman; Josiah C, Hoskins (1986). "Notable computer networks". Communications of the ACM. 29 (10): 932–971. doi:10.1145/6617.6618. S2CID25341056. The first packet-switching network was implemented at the National Physical Laboratories in the United Kingdom. It was quickly followed by the ARPANET in 1969.
"Alan Turing and the Ace computer". 5 February 2010. Retrieved 5 June 2024. The NPL network ran at multi-megabit speeds in the late 1960s, faster than any network at the time.
Guardian Staff (25 June 2013). "Internet pioneers airbrushed from history". The Guardian. ISSN0261-3077. Retrieved 31 July 2020. This was the first digital local network in the world to use packet switching and high-speed links.
Kleinrock, L. (1978). "Principles and lessons in packet communications". Proceedings of the IEEE. 66 (11): 1320–1329. doi:10.1109/PROC.1978.11143. ISSN0018-9219. Paul Baran ... focused on the routing procedures and on the survivability of distributed communication systems in a hostile environment, but did not concentrate on the need for resource sharing in its form as we now understand it; indeed, the concept of a software switch was not present in his work.
Pelkey, James L. "6.1 The Communications Subnet: BBN 1969". Entrepreneurial Capitalism and Innovation: A History of Computer Communications 1968–1988. As Kahn recalls: ... Paul Baran's contributions ... If you look at what he wrote, he was talking about switches that were low-cost electronics. The idea of putting powerful computers in these locations hadn't quite occurred to him as being cost effective. So the idea of computer switches was missing. The whole notion of protocols didn't exist at that time. And the idea of computer-to-computer communications was really a secondary concern.
Clarke, Peter (1982). Packet and circuit-switched data networks(PDF) (PhD thesis). Department of Electrical Engineering, Imperial College of Science and Technology, University of London. "As well as the packet switched network actually built at NPL for communication between their local computing facilities, some simulation experiments have been performed on larger networks. A summary of this work is reported in [69]. The work was carried out to investigate networks of a size capable of providing data communications facilities to most of the U.K. ... Experiments were then carried out using a method of flow control devised by Davies [70] called 'isarithmic' flow control. ... The simulation work carried out at NPL has, in many respects, been more realistic than most of the ARPA network theoretical studies."
Wilkinson, Peter (2001). NPL Development of Packet Switching. Symposium of the Institution of Analysts & Programmers 2001. Archived from the original on 7 August 2003. Retrieved 13 June 2024. The feasibility studies continued with an attempt to apply queuing theory to study overall network performance. This proved to be intractable so we quickly turned to simulation.
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. ISSN1934-1547. S2CID206443072.
"Smithsonian Oral and Video Histories: Vinton Cerf". National Museum of American History. Smithsonian Institution. 24 April 1990. Retrieved 23 September 2019. Roger Scantlebury was one of the major players. And Donald Davies who ran, at least he was superintendent of the information systems division or something like that. I absolutely had a lot of interaction with NPL at the time. They in fact came to the ICCC 72 and they had been coming to previous meetings of what is now called Datacomm. Its first incarnation was a long title having to do with the analysis and optimization of computer communication networks, or something like that. This started in late 1969, I think, was when the first meeting happened in Pine Hill, Georgia. I didn't go to that one, but I went to the next one that was at Stanford, I think. That's where I met Scantlebury, I believe, for the first time. Then I had a lot more interaction with him. I would come to the UK fairly regularly, partly for IFIP or INWG reasons
Cerf, V.; Kahn, R. (1974). "A Protocol for Packet Network Intercommunication"(PDF). IEEE Transactions on Communications. 22 (5): 637–648. CiteSeerX10.1.1.113.7384. doi:10.1109/TCOM.1974.1092259. ISSN1558-0857. 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.
Derek Barber. "The Origins of Packet Switching". Computer Resurrection Issue 5. Retrieved 5 June 2024. I actually set up the first meeting between John Wedlake of the British Post Office and [Rémi Després] of the French PTT which led to X25. There was a problem about virtual calls in EIN, so I called this meeting and that actually did in the end lead to X25.
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. S2CID36954091.
Davies, Donald Watts; Barber, Derek L. A. (1973), Communication networks for computers, Computing and Information Processing, John Wiley & Sons, ISBN9780471198741
Abbate 1999, p.3 "The manager of the ARPANET project, Lawrence Roberts, assembled a large team of computer scientists ... and he drew on the ideas of network experimenters in the United States and the United Kingdom. Cerf and Kahn also enlisted the help of computer scientists from England, France and the United States" harvnb error: no target: CITEREFAbbate1999 (help)
"Alan Turing and the Ace computer". BBC. 5 February 2010. Retrieved 13 February 2024. Does that mean Britain invented the internet? "Yes and no," said Mr Scantlebury. "Certainly the underlying technology of the internet, which is packet switching, we did invent."
"A Flaw in the Design". The Washington Post. 30 May 2015. Archived from the original on 8 November 2020. Retrieved 20 February 2020. The Internet was born of a big idea: Messages could be chopped into chunks, sent through a network in a series of transmissions, then reassembled by destination computers quickly and efficiently. Historians credit seminal insights to Welsh scientist Donald W. Davies and American engineer Paul Baran. ... The most important institutional force ... was the Pentagon's Advanced Research Projects Agency (ARPA) ... as ARPA began work on a groundbreaking computer network, the agency recruited scientists affiliated with the nation's top universities.
Roberts, Lawrence G. (November 1978). "The evolution of packet switching"(PDF). Proceedings of the IEEE. 66 (11): 1307–13. doi:10.1109/PROC.1978.11141. S2CID26876676. Significant aspects of the network's internal operation, such as routing, flow control, software design, and network control were developed by a BBN team consisting of Frank Heart, Robert Kahn, Severo Omstein, William Crowther, and David Walden
F.E. Froehlich, A. Kent (1990). The Froehlich/Kent Encyclopedia of Telecommunications: Volume 1 - Access Charges in the U.S.A. to Basics of Digital Communications. CRC Press. p.344. ISBN0824729005. Although there was considerable technical interchange between the NPL group and those who designed and implemented the ARPANET, the NPL Data Network effort appears to have had little fundamental impact on the design of ARPANET. Such major aspects of the NPL Data Network design as the standard network interface, the routing algorithm, and the software structure of the switching node were largely ignored by the ARPANET designers. There is no doubt, however, that in many less fundamental ways the NPL Data Network had and effect on the design and evolution of the ARPANET.
"BT ad gets into a muddle about the internet's origins". BBC. 15 February 2016. Retrieved 25 September 2017. Although University College London subsequently helped test the networking protocols that gave rise to what we now recognise as the internet, much of the original work on them had been carried out at Stanford. "While Donald Davies and his team at the National Physical Laboratory can lay claim to having developed packet-switching that enabled the technological infrastructure of the internet, Vint Cerf and a number of Americans were the driving forces behind the Arpanet that became the internet," commented Prof Martin Campbell-Kelly, a trustee at The National Museum of Computing.
by Vinton Cerf, as told to Bernard Aboba (1993). "How the Internet Came to Be". Archived from the original on 26 September 2017. Retrieved 25 September 2017. We began doing concurrent implementations at Stanford, BBN, and University College London. So effort at developing the Internet protocols was international from the beginning.
Davies, D.W. (February 1967), A Store-and-Forward Communication Network for Real-Time Computers and their Peripherals. PO Colloquium on Message Switching.
Scantlebury, R. A.; K. A. Bartlett (February 1967). An NPL Data Communications Network Based on the Plessey XL12 Computer. Private papers.
Scantlebury, R. A.; Bartlett, K. A. (April 1967), A Protocol for Use in the NPL Data Communications Network, Private papers.
Davies, D.W. (July 1967) Some Design Aspects of a Communication Network for Rapid-Response Computers. Computer Technology Conference.
Scantlebury, R. A.; Wilkinson, P.T. (1971). The design of a switching system to allow remote access to computer services by other computers and terminal devices. Proceedings of the 2nd Symposium on Problems in the Optimization of Data Communications Systems. pp.160–167.
Barber, D. L. A. (1972). Winkler, S (ed.). "The European computer network project". Computer Communications: Impacts and Implications. Washington, D.C.: 192–200.
