Saturday, November 24, 2012

The History of Internet

History of the Internet

We use internet everyday and maybe our live depend on it. No internet mean no income,entertain, information and other.Well internet have been usefull seen it's first launch.But do we know the history?
1960s-1970s: ARPANET: Commonly thought of as the predecessor to the Internet and created by the US Department of Defenses Advanced Research Projects Agency (ARPA). The first known fully operational packet-switching network, the ARPANET was designed to facilitate communication between ARPA computer terminals during the early 1960s, at a time when computers where far too expensive for widespread usage. Though conception of the idea behind ARPANET began as early as 1962, the first stable link between multiple computers through the ARPANET occurred in 1969, ten years after the first conceptual network architectural models were initiated independently by Paul Baran and Donald Davies.
Though a primary element of pushing the creation of the ARPANET was the ever-present concept of humanitys continual evolution and technological advancement, there were simple and practical concerns that also under-girded the development of the ARPANET. At the time, ARPA was a primary source of funding for computer development and research. During this early computing age, computers were incredibly expensive to produce and operate, and were separated by distance and purpose, forcing a single user wishing to access multiple operational functions and information to physically travel to the site of multiple computers. One of the practical elements that necessitated the development of the ARPANET was the need to efficiently link multiple computers together which would allow users to access the specified functions of different computers and data without the cost of travel and time. Additionally, given that ARPA was an agency of the Defense Department, part of the motivation was related to the desire of the U.S. Military to develop a survivable communication structure in the event of nuclear attack, (though this was not the primary motivating factor that it is often emphasized to be.) After a decade of remaining a closed computer network ARPANET transformed into the openly networked Internet of the modern age.

1962-63: Working at the Massachusetts Institute of Technology (MIT), J.C.R. Licklider authored a series of memos concerning theoretical network structures. His concept of a Galactic Network envisioned a world-wide computer network in which computer terminals would be linked to one another, allowing anyone with access to a terminal the ability to access and send information to other computers and users. While working at the Department of Defenses Advanced Research Projects Agency (ARPA), Licklider stressed the importance of realizing this network design to his colleagues who would later go on to realize elements of the Galactic Network concept in the actualized form of the ARPANET, an early predecessor to the Internet.

1959-1964: Stemming from an interest in the survivability of communications networks in the event of a Soviet Nuclear attack, Paul Baran, an engineer at the RAND military think tank, developed a conceptual model of communication called distributed communications. Conventional models of communications, like contemporary phone lines, transfer communications from an origin point on to a local node and then on to the receiver or to a national node should the call need to go to a receiver beyond the regional area. In this sort of communications framework, eliminating regional or national nodes severely damages the entire network making communication nearly impossible. In Barans distributed communications model, communications would go from the origin point and then onto one of many different switching nodes rather than a single regional or national node. This would allow for safer communication should any given node be eliminated because there would still be multiple nodes and pathways for a communication to move across.

1965: The first network experiment linking two computers takes place between the TX-2 computer by Lincoln Labs and the Q-32 mainframe operated by the RAND corporations System Development Corporation. It is the first time in which two computers directly communicated with one another.

1966: Shortly after coming to ARPA in 1966, Lawrence Roberts published a plan for the ARPANET which utilized the concept of a computer network developed by J.C.R. Licklider and MIT researcher Leonard Kleinrock who first investigated the concept of packet switching in which blocks of data (or packets) could be sent over a linked network of nodes in such a way that network nodes could delay the routing of the data packets and pass them on to other nodes. Packet switching as a communications network differs from the alternative of circuit switching in which there are a limited number of constant communications between nodes that are only active for the duration of the communication, like a phone line. Packet switching as a method of communication was a break through over circuit switching because it allows for a more efficient use of a network by increasing the ability of a network communication to function regardless of abnormalities and decreasing the amount of time it takes for a packet of data to move across a given network. Advancing on Kleinrock and others works, Roberts published the first plan for the creation of the ARPANET in 1967 and with the help of other researchers and theoretical works, the ARPANET was planed and built with the first node of ARPANET installed at the UCLA Network Measurement Center in 1969 followed by nodes at the Stanford Research Institute, The University of California at Santa Barbara, and the University of Utah.