The NPL Network or NPL Data Communications Network was a local area computer network operated by a team from the National Physical Laboratory in London that pioneered the concept of packet switching.
Based on designs first proposed by Donald Davies in 1965, elements of the first version of the network, the Mark I, became operational during 1969 then fully operational in 1970, and the Mark II version operated from 1973 until 1986. The NPL network and the ARPANET in the United States were the first two computer networks that implemented packet switching and the NPL network was the first to use high-speed links.
In 1965, Donald Davies, who was later appointed to head of the NPL Division of Computer Science, proposed a commercial national data network based on packet switching in Proposal for the Development of a National Communications Service for On-line Data Processing. After the proposal was not taken up nationally, during 1966 he headed a team which produced a design for a local network to serve the needs of NPL and prove the feasibility of packet switching.The design was the first to describe the concept of an "Interface computer", today known as a router.
The next year, a written version of the proposal entitled NPL Data Network was presented by Roger Scantlebury at the Symposium on Operating Systems Principles. It described how computers ( nodes ) used to transmit signals ( packets ) would be connected by electrical links to re-transmit the signals between and to the nodes, and interface computers would be used to link node networks to so-called time-sharing computers and other users. The interface computers would transmit multiplex signals between networks, and nodes would switch transmissions while connected to electrical circuitry functioning at a rate of processing amounting to mega-bits.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".
Larry Roberts incorporated these concepts into the design for the ARPANET.The NPL network proposed a line speed of 768 kbit/s. Influenced by this, the planned line speed for ARPANET was upgraded from 2.4 kbit/s to 50 kbit/s and a similar packet format adopted.
The first theoretical foundation of packet switching was the work of Paul Baran, in which data was transmitted in small chunks and routed independently by a method similar to store-and-forward techniques between intermediate networking nodes.Davies independently arrived at the same model in 1965 and named it packet switching. 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. Davies gave the first public presentation of packet switching on 5 August 1968. Concurrently with the ARPANET, NPL under Davies was one of the first two organisations that implemented a packet switching network.
The NPL team used their packet switching concept to produce an experimental network using a Honeywell 516 node. Coincidentally, this was the same computer chosen by the ARPANET to serve as Interface Message Processors.
Construction began in 1968.Elements of the first version of the network, Mark I NPL Network, became operational during 1969 then fully operational in January 1970, later using high-speed T1 links (1.544 Mbit/s line rate), the first computer network to do so. The Mark II version operated from 1973. The NPL team also carried out simulation work on the performance of packet networks, including datagram networks. The local area NPL network and the wide area ARPANET in the United States were the first two computer networks that implemented packet switching.
The NPL network was later interconnected with other networks, including the ARPANET via Peter Kirstein's research group at University College London in 1973, and CYCLADES via the European Informatics Network (EIN) in 1976.
In 1976, 12 computers and 75 terminal devices were attached,and more were added. The network remained in operation until 1986, influencing other research in the UK and Europe.
Alongside Donald Davies, the NPL team included Derek Barber, Roger Scantlebury, Peter Wilkinson, Keith Bartlett, and Brian Aldous.
One of the first uses of the term 'protocol' in a data-commutation 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.The Mark II version which operated from 1973 used a layered protocol architecture.
The NPL network was a tesbed for internetworking research throughout the 1970s. Davies, Scantlebury and Barber were members of the International Networking Working Group (INWG) which proposed a protocol for internetworking.Derek Barber was appointed director of the European COST 11 project which became the European Informatics Network (EIN) while Scantlebury led the UK technical contribution. The EIN protocol helped to launch the proposed INWG standard. Bob Kahn and Vint Cerf acknowledged Davies and Scantlebury in their 1974 paper "A Protocol for Packet Network Intercommunication".
NPL research 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.
Davies and Barber published books on "communication networks for computers" in 1973 and "computer networks and their protocols" in 1979.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". 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.
Davies' research at NPL later focused on data security for computer networks.
NPL sponsors a gallery, opened in 2009, about the development of packet switching and "Technology of the Internet" at The National Museum of Computing.
The history of the Internet has its origin in the efforts to build and interconnect computer networks that arose from research and development in the United States and involved international collaboration, particularly with researchers in the United Kingdom and France.
Internetworking is the practice of interconnecting multiple computer networks, such that any pair of hosts in the connected networks can exchange messages irrespective of their hardware-level networking technology. The resulting system of interconnected networks are called an internetwork, or simply an internet.
In telecommunications, packet switching is a method of grouping data that is transmitted over a digital network into packets. Packets are made of a header and a payload. Data in the header is used by networking hardware to direct the packet to its destination, where the payload is extracted and used by application software. Packet switching is the primary basis for data communications in computer networks worldwide.
The end-to-end principle is a design framework in computer networking. In networks designed according to this principle, application-specific features reside in the communicating end nodes of the network, rather than in intermediary nodes, such as gateways and routers, that exist to establish the network.
The National Physical Laboratory (NPL) is the national measurement standards laboratory for the United Kingdom. Founded in 1900, it is one of the oldest standardising laboratories in the world.
The Advanced Research Projects Agency Network (ARPANET) was the first wide-area packet-switching network with distributed control and one of the first networks to implement the TCP/IP protocol suite. Both technologies became the technical foundation of the Internet. The ARPANET was established by the Advanced Research Projects Agency (ARPA) of the United States Department of Defense.
Donald Watts Davies, was a Welsh computer scientist who was employed at the UK National Physical Laboratory (NPL).
Paul Baran was a Polish-American engineer who was a pioneer in the development of computer networks. He was one of the two independent inventors of packet switching, which is today the dominant basis for data communications in computer networks worldwide, and went on to start several companies and develop other technologies that are an essential part of modern digital communication.
Wesley Allison Clark was an American physicist who is credited for designing the first modern personal computer. He was also a computer designer and the main participant, along with Charles Molnar, in the creation of the LINC computer, which was the first minicomputer and shares with a number of other computers the claim to be the inspiration for the personal computer.
The CYCLADES computer network was a French research network created in the early 1970s. It was one of the pioneering networks experimenting with the concept of packet switching and, unlike the ARPANET, was explicitly designed to facilitate internetworking.
The Interface Message Processor (IMP) was the packet switching node used to interconnect participant networks to the ARPANET from the late 1960s to 1989. It was the first generation of gateways, which are known today as routers. An IMP was a ruggedized Honeywell DDP-516 minicomputer with special-purpose interfaces and software. In later years the IMPs were made from the non-ruggedized Honeywell 316 which could handle two-thirds of the communication traffic at approximately one-half the cost. An IMP requires the connection to a host computer via a special bit-serial interface, defined in BBN Report 1822. The IMP software and the ARPA network communications protocol running on the IMPs was discussed in, the first of a series of standardization documents published by the Internet Engineering Task Force (IETF).
Lawrence Gilman Roberts was an American engineer who received the Draper Prize in 2001 "for the development of the Internet", and the Principe de Asturias Award in 2002.
Peter Thomas Kirstein was a British computer scientist who played a role in the creation of the Internet. He put the first computer on the ARPANET outside of the US and was instrumental in defining and implementing TCP/IP alongside Vint Cerf and Bob Kahn. He is "often recognized as the father of the European Internet".
The United Kingdom has been involved with the Internet throughout its origins and development. The telecommunications infrastructure in the United Kingdom provides Internet access to businesses and home users in various forms, including cable, DSL, wireless and mobile.
The Symposium on Operating Systems Principles (SOSP), organized by the Association for Computing Machinery (ACM), is one of the most prestigious single-track academic conferences on operating systems.
SATNET, also known as the Atlantic Packet Satellite Network, was an early satellite network that formed an initial segment of the Internet. It was implemented by BBN Technologies under the direction of the Advanced Research Projects Agency.
Roger Anthony Scantlebury is a British computer scientist who worked at the National Physical Laboratory (NPL) and later at Logica.
The International Networking 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, it became a subcommittee of the International Federation for Information Processing later that year. Ideas developed by members of the group contributed to the original "Protocol for Packet Network Intercommunication" proposed by Bob Kahn and Vint Cerf in 1974.
A long-running debate in computer science known as the Protocol Wars occurred from the 1970s to the 1990s when engineers, organizations and nations became polarized over the issue of which communication protocol would result in the best and most robust computer networks. This culminated in the Internet–OSI Standards War in the late 1980s and early 1990s.
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.
Elements of the pilot NPL network first operated in 1969
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.
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
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.
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.
Although he was aware of the concept of packet switching, Roberts was not sure how to implement it in a large network.
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. May 30, 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.
Transmission of packets of data over the high-speed lines
Both Paul Baran and Donald Davies in their original papers anticipated the use of T1 trunks
This was the first digital local network in the world to use packet switching and high-speed links.
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.