1.2 History of the Internet


The Internet that exists today is the unintended outcome of the initial research objectives set by the Advanced Research Projects Agency (ARPA) of the United States Department of Defense (DOD) in the late 1960s.

The origins and history of the Internet go back as far as the early 1960s, and the ideas for the Internet as we know it today can be gleaned from memos written in August 1962 by J.C.R. Licklider, who discussed the concept of a "Galactic Network." Leonard Kleinrock of the Massachusetts Institute of Technology (MIT) published the first paper on packet-switching theory in July 1961.

In the mid-1960s ARPA formulated a research interest in computer networks. ARPA is essentially an organization that does not directly do research by itself, but funds research work based on topics defined by it and manages these projects. In 1965 ARPA funded a study through Lawrence Roberts at MIT's Lincoln Laboratory, largely as a result of Kleinrock's earlier work at MIT. The study report, "A Cooperative Network of Time-Sharing Computers," proposed to establish an experimental three-computer network. This proposal was successfully implemented a year later by Roberts and Thomas Merill when they connected the TX-2 computer at MIT to the Q-32 in California through a low-speed dial-up telephone line. A third computer located at ARPA was later connected to this network as well. This experimental network generated a great amount of interest in the computer research community and accelerated further developments. In late 1966, Roberts went to the Defense Advanced Research Projects Agency (former name of ARPA) to develop the computer network concept and came up with a plan for the ARPANET and published it in 1967. In 1968, ARPA invited prospective suppliers to build the network and in 1968 awarded the contract for ARPANET to Bolt Beranek and Newman (BBN). On September 1, 1969, the first Interface Message Processor (IMP) was shipped to the University of California at Los Angeles (UCLA) and the first host computer was connected. The IMP at UCLA was connected to IMPs subsequently shipped to the Stanford Research Institute (SRI), the University of California at Santa Barbara (UCSB), and the University of Utah. In December 1970, Steve Crocker finished the initial ARPANET host-to-host protocol, called Network Control Protocol (NCP), and ARPANET sites completed implementing NCP during 1971-1972. In October 1972 a large successful demo of the ARPANET took place. Electronic mail was also introduced in 1972. Soon the ARPANET grew to include packet radio networks (ALOHA-net), packet satellite networks, and others.

The refinement of the ARPANET networking model was undertaken by Robert Kahn in 1972. The model of the ARPANET was to connect heterogeneous hosts via a homogeneous network. The concept that Kahn introduced was to allow the network itself to be heterogeneous. After joining DARPA and initiating the Internet program, Kahn enlisted Vinton Cerf of Stanford University to work with him on the detailed design of the protocol. Cerf, who had been involved earlier in the design of NCP, was already knowledgeable about interfacing to existing operating systems. Kahn and Cerf teamed up and came up with the specification for the Kahn-Cerf protocol, which was later named the Transmission Control Protocol/Internet Protocol (TCP/IP). The paper "A Protocol for Packet Network Interconnection," published in May 1974, described TCP and provided all the Internet's transport and forwarding services. The design intent was to have TCP support a range of transport services ranging from sequenced , in-order reliable delivery of data to a datagram service that was less than robust (lossy) and did not guarantee in-order packet delivery. Initial TCP implementations resulted in essentially a protocol that emulated virtual circuits. This model was fine for applications such as file transfer and remote login, but other applications such as packet voice demonstrated that it is not always necessary for the transport protocol to correct errors. That is best left to applications that obviously have their own requirements. This resulted in some changes to the initial proposal, and the outcome was two transport protocols: TCP and User Datagram Protocol (UDP). UDP was added as an unreliable datagram transport protocol for applications that did not need error correction, retransmissions, and congestion management.

DARPA funded Stanford (Cerf), BBN (Tomlinson), and University College London (Peter Kirstein) to implement TCP. Stanford produced a detailed specification from which multiple implementations were produced. Early implementations of TCP were for large time-sharing systems, but David Clark and his research group at MIT proved that the protocol could be adapted as well to small host computers and workstations. The 1980s introduced localarea networks (LANs), PCs, and workstations. Ethernet technology took off on a very large scale. This allowed Internet technology to take hold at the grassroots level. A bigger challenge was to make the technology widely available and have it adapted by multiple people. DARPA supported the University of California at Berkeley, which had developed a version of the Unix operating system. Berkeley developed the TCP/IP code and fit it into the Unix system kernel. Berkeley Software Distribution (BSD) Unix, which was quite popular with the computer science community, adopted the Internet technology and helped foster its growth even further.

TCP/IP was adopted as a defense standard in 1980. The ARPANET was being used by both military and the research community. The ARPANET transitioned from NCP to TCP in 1983, and at the same time the network was split into MILNET (supporting the defense department) and an ARPANET (supporting the research community).

The usefulness of computer networking and applications such as e-mail was recognized by other communities as well, and as a result a host of networks began springing up. In 1985 the U.S. NSFNET (National Science Foundation Network ”the Internet backbone in the U.S. which was supported by NSF) program announced its intent to serve the entire higher-education community. NSFNET also mandated TCP/IP for this network. Thus developed the NSFNET backbone. NSFNET, which was funded by federal funds, ended in 1995 and the research network transitioned into a commercial network. In an 8.5-year span the backbone had grown from 6 nodes to 21 nodes. The Internet also constituted more than 50,000 networks on all continents (with 29,000 networks in the United States). The ARPANET was decommissioned in 1990. TCP/IP had spread so vigorously that it made other networking protocols irrelevant or marginal and ensured the success of IP for the future.



IP in Wireless Networks
IP in Wireless Networks
ISBN: 0130666483
EAN: 2147483647
Year: 2003
Pages: 164

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