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ARPAnet 1973
ARPAnet 1977

The ARPANET ( A dvanced R esearch P rojects A gency Net work ) was a computer network and was originally commissioned by the US Air Force from 1968 by a small group of researchers led by the Massachusetts Institute of Technology and the Department of Defense US- developed. It is the forerunner of today's internet . Paul Baran ( RAND study) and Donald Watts Davies (decentralized network structure and packet switching ) provided important findings from the field of partially meshed network topology and packet-switched networks, which were incorporated into the development of the Arpanet as a basis for communication.

History and purpose

A decentralized network was to be created that connected different US universities that did research for the Department of Defense. The decentralized concept, which was revolutionary at the time, already contained the fundamental aspects of today's Internet. The connections were made via telephone lines .

The earliest ideas for a computer network ( computer network ) should enable general communication between several computer users. As early as August 1962, computer scientists JCR Licklider , Leo Beranek , Richard Bolt and Robert Newman presented such concepts for an "Intergalactic Computer Network". These ideas already contained almost everything that defines the modern Internet today.

In October 1962, Licklider became the head of the Advanced Research Projects Agency (ARPA). He convinced Ivan Sutherland and Bob Taylor that the concept of a computer network already presented was future-oriented and inevitable. Sutherland and Taylor conducted further research into its realization.

The project was initially rejected by the United States Department of Defense , but revived in 1965 and implemented in 1969. Initially, the network only networked the four research institutions Stanford Research Institute , University of Utah , University of California, Los Angeles and the University of California, Santa Barbara .

On August 5, 1968, the concept was packet switching (English "packet switching") for the first time presented to the public in the UK, could be shipped which communication messages into packets divided - a new concept that is now the dominant basis for global data communication forms. Before the advent of packet switching, voice and data communication was based on the idea of ​​traditional circuit switching between two telephone lines through a direct electronic link. This typical leased line consists of several transmission lines one behind the other, which are joined together to form a chain. Their course extends from the original station to the destination station, whereby the infrastructure used is not available for further connections during this time. In the case of packet switching, on the other hand, the packets traverse the network as independent and autonomous units and can be temporarily stored in the switching nodes. This is a major advantage, since the transmission speed between individual sections is no longer a limit. However, this also creates a network of queues. Each network node to be passed receives the packet and forwards it to its network node output interface. Since this interface can be the target of many broadcasts, there is a tendency to overload. As a rule, the user does not receive any information about the transmission path, since these transmission paths change dynamically.

During the same period, the Unix operating system and the underlying C programming language were developed. Unix could easily be transferred to different computer architectures using C and thus became the quasi-standard in the Arpanet, which made the development of communication applications and protocols easier. It made a major contribution to the creation of today's Internet in the early 1980s. Even today, operating systems derived from it, especially Linux , are the most frequently used in servers and communication devices.

The ARPANET provided a uniform way of communicating over long distances, as is common today.


On April 7, 1969, ARPA awarded the contract to build a network to BBN Technologies . A small network of computers, which were run together as an Interface Message Processor (IMP) and which were connected by gateways (today routers ), was set up. The first data transfer took place on October 29, 1969 between computers at the University of California, Los Angeles , and the Stanford Research Institute near San Francisco.

At each location, the IMPs carried out store-and-forward switching functions and were connected by modems via leased lines at an initial speed of 50 kbit / s. The entire system, including hardware, software and packet switching, was developed and installed in nine months.


In 1971 the go-ahead was given for the use of the much easier-to-use Honeywell H316 mini-computers instead of the previous IMPs. The H316 series provided a higher level of integration. In 1975 BBN introduced new IMP software on a Pluribus multi-processor .

In 1983, TCP / IP protocols were used in the ARPANET, making the ARPANET a subnet of the early Internet.

Shutdown and end

The original IMPs of the ARPANET were switched off or expired after the introduction of the NSFNet . However, some IMPs remained in operation until 1989.

The ARPANET was officially shut down on February 28, 1990.

The Arpanet and the nuclear war

The Internet Society , in A Brief History of the Internet, notes on the relationship between the Arpanet and the so-called RAND study, which looked at military communications networks in times of nuclear war:

“The RAND study is based on the false rumor that the Arpanet is linked to the creation of a nuclear war- resistant network. This never applied to the Arpanet, only to the independent RAND study on secure telephone connections during nuclear war. However, later work highlighted the robustness and survivability of the Internet, including the ability to withstand large losses in the underlying networks. "

However, the myth that the Arpanet was designed to withstand nuclear attacks is still such a strong and compelling idea and "good story" that many people do not believe it is wrong. Apart from the fact that the development of the Arpanet was influenced by the RAND articles, it is at least officially wrong. According to the ARPA, a method was rather sought to better utilize the then scarce computing capacities of the individual universities by exchanging data. The Arpanet was later expanded to compensate for network losses, but the main reason was the network connections, which were sensitive even without nuclear attacks.

See also


  • J. Abbate: Inventing the Internet. MIT Press, Cambridge, Mass. 1999
  • Katie Hafner, Matthew Lyon: ARPA KADABRA or The History of the Internet. dpunkt-Verlag, Heidelberg 2000, ISBN 3-932588-59-2
  • PH Salus: Casting the Net: From ARPANET to INTERNET and beyond ... Addison-Wesley, Reading, Mass. 1995
  • Michael Hauben, Ronda Hauben: Netizens: On the History and Impact of Usenet and the Internet. Wiley-IEEE Computer Society Press, 1997, ISBN 0-8186-7706-6 . Online version
  • John Naughton: A Brief History of the Future: The Origins of the Internet. Phoenix, London 2000
  • M. Friedewald: From the experimental field to the mass medium: Formative forces in the development of the Internet. In: Technikgeschichte 67, No. 4, pp. 331–361, 2000
  • Martin Schmitt: "Internet in the Cold War. A prehistory of the global communication network." Transcript, Bielefeld 2016, ISBN 978-3-8376-3681-9 Introduction
  • Thomas Walach: Early Net Democracy? Possibilities and limits of user participation in the Arpanet . In: Technikgeschichte, Vol. 86 (2019), H. 2, pp. 131–152.

Web links

Individual evidence

  1. Daily Bruin: Browsing history: A heritage site is being set up in Boelter Hall 3420, the room the first Internet message originated in April 1, 2011
  2. ^ A Brief History of the Internet