History of Computer Networking and the Internet

History of Computer Networking and the Internet

So far what we have studied, presented an overview of the technology of computer networking and the Internet. You should know enough now to impress your family and friends! However, if you really want to be a big hit at the next cocktail party, you should sprinkle your discourse with tidbits about the attractive history of the Internet [SegalIer 1998].

The Development of Packet Switching: 1961-1972

The field of computer networking and today's Internet trace their beginnings back to the early 1960s, when the telephone network was the world's leading communication network. Recall from "The Network Core" that the telephone network uses circuit switching to broadcast information from a sender to a receiver - an appropriate choice given that voice is transmitted at a constant rate between sender and receiver. Given the increasing importance (and great expense) of computers in the early 1960s and the arrival of timeshared computers, it was perhaps natural (at least with perfect hindsight!) to deal with the question of how to hook computers together so that they could be shared among geographically distributed users. The traffic generated by such users was likely to be bursty - intervals of activity, such as the sending of a command to a remote computer, followed by periods of inactivity while waiting for a reply or while contemplating the received response.

Three research groups around the world, each uninformed of the others work [Leiner 1998], began inventing packet switching as an well-organized and strong substitute to circuit switching. The first published work on packet-switching techniques was that of Leonard Kleinrock [Kleinrock 1961 ; Kleinrock 1964], then a graduate student at MIT. Using queuing theory, Kleinrock's work elegantly showed the effectiveness of the packet-switching approach for bursty traffic sources. In 1964, Paul Baran [Baran 1964] at the Rand Institute had begun investigating the use of packet switching for secure voice over military networks, and at the National Physical Laboratory in England, Donald Davies and Roger Scantlebury were also developing their ideas on packet switching.

The work at MIT, Rand, and the NPL laid the foundations for today's Internet. But the Internet also has a long history of a let's-build-it-and-demonstrate-it approach that also dates back to the 1960s. J. C. R. Licklider [DEC 1990] and Lawrence Roberts, both colleagues of Kleinrock's at MIT, went on to lead the computer science program at the Advanced Research Projects Agency (ARPA) in the United States. Roberts published an overall plan for the ARPAnet [Roberts 1967], the first packet-switched computer network and a direct ancestor of today's public Internet. The early packet switches were known as interface message processors (IMPS), and the contract to build these switches was awarded to the BBN company. On Labor Day in 1969, the first IMP was installed at UCLA under Kleinrock's supervision, and three additional IMPs were installed shortly thereafter at the Stanford Research Institute (SRI), UC Santa Barbara, and the University of Utah (the following figure). The fledgling forerunner to the Internet was four nodes large by the end of 1969. Kleinrock recalls the very first use of the network to execute a remote login from UCLA to SRI, crashing the system [Kleinrock 2004].

By 1972, ARPAnet had grown to about 15 nodes and was given its first public demonstration by Robert Kahn at the 1972 International Conference on Computer Communications. The First host-to-host protocol between ARPAnet end systems, known as the network-control protocol (NCP), was completed [RFC 001]. With an end-to-end protocol available, applications could now be written. Ray Tomlinson at BBN wrote the first e-mail program in 1972.

An early interface message processor


circuit switching, timeshared computers, packet switching

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