History Of Internet

The history of the Internet originated in the efforts of scientists and engineers to build and interconnect computer networks. The Internet Protocol Suite, the set of rules used to communicate between networks and devices on the Internet, arose from research and development in the United States and involved international collaboration, particularly with researchers in the United Kingdom and France.

Computer science was an emerging discipline in the late 1950s that began to consider time-sharing between computer users, and later, the possibility of achieving this over wide area networks. J. C. R. Licklider developed the idea of a universal network at the Information Processing Techniques Office (IPTO) of the United States Department of Defense (DoD) Advanced Research Projects Agency (ARPA). Independently, Paul Baran at the RAND Corporation proposed a distributed network based on data in message blocks in the early 1960s, and Donald Davies conceived of packet switching in 1965 at the National Physical Laboratory (NPL), proposing a national commercial data network in the United Kingdom.

ARPA awarded contracts in 1969 for the development of the ARPANET project, directed by Robert Taylor and managed by Lawrence Roberts. ARPANET adopted the packet switching technology proposed by Davies and Baran. The network of Interface Message Processors (IMPs) was built by a team at Bolt, Beranek, and Newman, with the design and specification led by Bob Kahn. The host-to-host protocol was specified by a group of graduate students at UCLA, led by Steve Crocker, along with Jon Postel and others. The ARPANET expanded rapidly across the United States with connections to the United Kingdom and Norway.

Several early packet-switched networks emerged in the 1970s which researched and provided data networking. Louis Pouzin and Hubert Zimmermann pioneered a simplified end-to-end approach to internetworking at the IRIA. Peter Kirstein put internetworking into practice at University College London in 1973. Bob Metcalfe developed the theory behind Ethernet and the PARC Universal Packet. ARPA initiatives and the International Network Working Group developed and refined ideas for internetworking, in which multiple separate networks could be joined into a ''network of networks''. Vint Cerf, now at Stanford University, and Bob Kahn, now at DARPA, published their research on internetworking in 1974. Through the Internet Experiment Note series and later RFCs this evolved into the Transmission Control Protocol (TCP) and Internet Protocol (IP), two protocols of the Internet protocol suite. The design included concepts pioneered in the French CYCLADES project directed by Louis Pouzin. The development of packet switching networks was underpinned by mathematical work in the 1970s by Leonard Kleinrock at UCLA.In the late 1970s, national and international public data networks emerged based on the X.25 protocol, designed by Rémi Després and others. In the United States, the National Science Foundation (NSF) funded national supercomputing centers at several universities in the United States, and provided interconnectivity in 1986 with the NSFNET project, thus creating network access to these supercomputer sites for research and academic organizations in the United States. International connections to NSFNET, the emergence of architecture such as the Domain Name System, and the adoption of TCP/IP on existing networks in the United States and around the world marked the beginnings of the Internet. Commercial Internet service providers (ISPs) emerged in 1989 in the United States and Australia. Limited private connections to parts of the Internet by officially commercial entities emerged in several American cities by late 1989 and 1990. The optical backbone of the NSFNET was decommissioned in 1995, removing the last restrictions on the use of the Internet to carry commercial traffic, as traffic transitioned to optical networks managed by Sprint, MCI and AT&T in the United States.

Research at CERN in Switzerland by the British computer scientist Tim Berners-Lee in 1989–90 resulted in the World Wide Web, linking hypertext documents into an information system, accessible from any node on the network. The dramatic expansion of the capacity of the Internet, enabled by the advent of wave division multiplexing (WDM) and the rollout of fiber optic cables in the mid-1990s, had a revolutionary impact on culture, commerce, and technology. This made possible the rise of near-instant communication by electronic mail, instant messaging, voice over Internet Protocol (VoIP) telephone calls, video chat, and the World Wide Web with its discussion forums, blogs, social networking services, and online shopping sites. Increasing amounts of data are transmitted at higher and higher speeds over fiber-optic networks operating at 1 Gbit/s, 10 Gbit/s, and 800 Gbit/s by 2019. The Internet's takeover of the global communication landscape was rapid in historical terms: it only communicated 1% of the information flowing through two-way telecommunications networks in the year 1993, 51% by 2000, and more than 97% of the telecommunicated information by 2007. The Internet continues to grow, driven by ever greater amounts of online information, commerce, entertainment, and social networking services. However, the future of the global network may be shaped by regional differences.

Foundations

Precursors

Telegraphy

:The practice of transmitting messages between two different places through an electromagnetic medium dates back to the electrical telegraph in the late 19th century, which was the first fully digital communication system. Radiotelegraphy began to be used commercially in the early 20th century. Telex became an operational teleprinter service in the 1930s. Such systems were limited to point-to-point communication between two end devices.

Information theory

:Fundamental theoretical work in telecommunications technology was developed by Harry Nyquist and Ralph Hartley in the 1920s. Information theory, as enunciated by Claude Shannon in 1948, provided a firm theoretical underpinning to understand the trade-offs between signal-to-noise ratio, bandwidth, and error-free transmission in the presence of noise.

Computers and modems

:Early fixed-program computers in the 1940s were operated manually by entering small programs via switches in order to load and run a series of programs. As transistor technology evolved in the 1950s, central processing units and user terminals came into use by 1955. The mainframe computer model was devised, and modems, such as the Bell 101, allowed digital data to be transmitted over regular unconditioned telephone lines at low speeds by the late 1950s. These technologies made it possible to exchange data between remote computers. However, a fixed-line link was still necessary; the point-to-point communication model did not allow for direct communication between any two arbitrary systems. In addition, the applications were specific and not general purpose. Examples included SAGE (1958) and SABRE (1960).

Time-sharing

:Christopher Strachey, who became Oxford University's first Professor of Computation, filed a patent application in the United Kingdom for time-sharing in February 1959. In June that year, he gave a paper "Time Sharing in Large Fast Computers" at the UNESCO Information Processing Conference in Paris where he passed the concept on to J. C. R. Licklider.. "the first paper on time-shared computers by C. Strachey at the June 1959 UNESCO Information Processing conference". Licklider, a vice president at Bolt Beranek and Newman, Inc. (BBN), promoted the idea of time-sharing as an alternative to batch processing. John McCarthy, at MIT, wrote a memo in 1959 that broadened the concept of time sharing to encompass multiple interactive user sessions, which resulted in the Compatible Time-Sharing System (CTSS) implemented at MIT. Other multi-user mainframe systems developed, such as PLATO at the University of Illinois Chicago. In the early 1960, the Advanced Research Projects Agency (ARPA) of the United States Department of Defense funded further research into time-sharing at MIT through Project MAC.

Inspiration

J. C. R. Licklider, while working at BBN, proposed a computer network in his March 1960 paper '' Man-Computer Symbiosis'':

In August 1962, Licklider and Welden Clark published the paper "On-Line Man-Computer Communication" which was one of the first descriptions of a networked future.

In October 1962, Licklider was hired by Jack Ruina as director of the newly established Information Processing Techniques Office (IPTO) within ARPA, with a mandate to interconnect the United States Department of Defense's main computers at Cheyenne Mountain, the Pentagon, and SAC HQ. There he formed an informal group within DARPA to further computer research. He began by writing memos in 1963 describing a distributed network to the IPTO staff, whom he called "Members and Affiliates of the Intergalactic Computer Network".

Although he left the IPTO in 1964, five years before the ARPANET went live, it was his vision of universal networking that provided the impetus for one of his successors, Robert Taylor, to initiate the ARPANET development. Licklider later returned to lead the IPTO in 1973 for two years.

Packet switching

The infrastructure for telephone systems at the time was based on circuit switching, which requires pre-allocation of a dedicated communication line for the duration of the call. Telegram services had developed store and forward telecommunication techniques. Western Union's Automatic Telegraph Switching System Plan 55-A was based on message switching. The U.S. military's AUTODIN network became operational in 1962. These systems, like SAGE and SBRE, still required rigid routing structures that were prone to single point of failure.

The technology was considered vulnerable for strategic and military use because there were no alternative paths for the communication in case of a broken link. In the early 1960s, Paul Baran of the RAND Corporation produced a study of survivable networks for the U.S. military in the event of nuclear war. Information would be transmitted across a "distributed" network, divided into what he called "message blocks". Baran's design was not implemented.

In addition to being prone to a single point of failure, existing telegraphic techniques were inefficient and inflexible. Beginning in 1965 Donald Davies, at the National Physical Laboratory in the United Kingdom, independently developed a more advanced proposal of the concept, designed for high-speed computer networking, which he called packet switching, the term that would ultimately be adopted.

Packet switching is a technique for transmitting computer data by splitting it into very short, standardized chunks, attaching routing information to each of these chunks, and transmitting them independently through a computer network. It provides better bandwidth utilization than traditional circuit-switching used for telephony, and enables the connection of computers with different transmission and receive rates. It is a distinct concept to message switching.

Networks that led to the Internet

NPL network

Following discussions with J. C. R. Licklider in 1965, Donald Davies became interested in data communications for computer networks. Later that year, at the National Physical Laboratory (NPL) in the United Kingdom, Davies designed and proposed a national commercial data network based on packet switching. The following year, he described the use of "switching nodes" to act as routers in a digital communication network. The proposal was not taken up nationally but he produced a design for a local network to serve the needs of the NPL and prove the feasibility of packet switching using high-speed data transmission. To deal with packet permutations (due to dynamically updated route preferences) and to datagram losses (unavoidable when fast sources send to a slow destinations), he assumed that "all users of the network will provide themselves with some kind of error control", thus inventing what came to be known as the end-to-end principle. In 1967, he and his team were the first to use the term 'protocol' in a modern data-commutation context.

In 1968, Davies began building the Mark I packet-switched network to meet the needs of his multidisciplinary laboratory and prove the technology under operational conditions. The network's development was described at a 1968 conference. Elements of the network became operational in early 1969, the first implementation of packet switching, and the NPL network was the first to use high-speed links. Many other packet switching networks built in the 1970s were similar "in nearly all respects" to Davies' original 1965 design. The Mark II version which operated from 1973 used a layered protocol architecture. In 1977, there were roughly 30 computers, 30 peripherals and 100 VDU terminals all able to interact through the NPL Network. The NPL team carried out simulation work on wide-area packet networks, including datagrams and congestion; and research into internetworking and secure communications. "As well as the packet switched network actually built at NPL for communication between their local computing facilities, some simulation experiments have been performed on larger networks. A summary of this work is reported in 9 The work was carried out to investigate networks of a size capable of providing data communications facilities to most of the U.K. ... Experiments were then carried out using a method of flow control devised by Davies 0called 'isarithmic' flow control. ... The simulation work carried out at NPL has, in many respects, been more realistic than most of the ARPA network theoretical studies." The network was replaced in 1986.

ARPANET

Robert Taylor was promoted to the head of the Information Processing Techniques Office (IPTO) at Advanced Research Projects Agency (ARPA) in 1966. He intended to realize Licklider's ideas of an interconnected networking system. As part of the IPTO's role, three network terminals had been installed: one for System Development Corporation in Santa Monica, one for Project Genie at University of California, Berkeley, and one for the Compatible Time-Sharing System project at Massachusetts Institute of Technology (MIT). Taylor's identified need for networking became obvious from the waste of resources apparent to him.

Bringing in Larry Roberts from MIT in January 1967, he initiated a project to build such a network. Roberts and Thomas Merrill had been researching computer time-sharing over wide area networks (WANs). Wide area networks emerged during the late 1950s and became established during the 1960s. At the first ACM Symposium on Operating Systems Principles in October 1967, Roberts presented a proposal for the "ARPA net", based on Wesley Clark's idea to use Interface Message Processors (IMP) to create a message switching network. At the conference, Roger Scantlebury presented Donald Davies' work on a hierarchical digital communications network using packet switching and referenced the work of Paul Baran at RAND. Roberts incorporated the packet switching and routing concepts of Davies and Baran into the ARPANET design and upgraded the proposed communications speed from 2.4 kbit/s to 50 kbit/s.

ARPA awarded the contract to build the network to Bolt Beranek & Newman. The "IMP guys", led by Frank Heart and Bob Kahn, developed the routing, flow control, software design and network control. The first ARPANET link was established between the Network Measurement Center at the University of California, Los Angeles (UCLA) Henry Samueli School of Engineering and Applied Science directed by Leonard Kleinrock, and the NLS system at Stanford Research Institute (SRI) directed by Douglas Engelbart in Menlo Park, California at 22:30 hours on October 29, 1969.

By December 1969, a four-node network was connected by adding the Culler-Fried Interactive Mathematics Center at the University of California, Santa Barbara followed by the University of Utah Graphics Department. In the same year, Taylor helped fund ALOHAnet, a system designed by professor Norman Abramson

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