Computers & the Internet

Article by Imran Rashid

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 fascinating history of the Internet [Segaller 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 dominant communication network. Recall from Section 1.3 that the telephone network uses circuit switching to transmit 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 advent of timeshared computers, it was perhaps natuml (at least with perfect hindsight!) to consider 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 unaware of the others’ work [Leiner 1998], began inventing packet switching as an efficient and robust alternative to circuit switching. The first published work on packet-switching techniques was that of Leonard Kleinrock [Kleinrock 1961; Kleinrock 19641], then a graduate student at MIT. Using queuing theory, Klein rock’s work elegantly demonstrated 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 Scantle Bury 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 attitude 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 fledgling precursor to the Internet was four nodes large by the end of 1969. Kleinrock recalls the very first use of the network to perform a remote login from UCLA to SRI, crashing the system [Kleinrock 2004]. By 1972, ARPAnet had grown to approximately 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.

About the Author

Imran Rashid has working knowledge about windows operating systems.For more information visit

Free CCNA Tests

Free Windows Certification