The Internet has revolutionized the
computer and communications world like nothing before. The invention of the
telegraph, telephone, radio, and computer set the stage for this unprecedented
integration of capabilities. The Internet is at once a world-wide broadcasting
capability, a mechanism for information dissemination, and a medium for
collaboration and interaction between individuals and their computers without
regard for geographic location.
The Internet represents one of the
most successful examples of the benefits of sustained investment and commitment
to research and development of information infrastructure. Beginning with the
early research in packet switching, the government, industry and academia have
been partners in evolving and deploying this exciting new technology. Today,
terms like "bleiner@computer.org" and "#"#">4 starting in October 1962. While at
DARPA he convinced his successors at DARPA, Ivan Sutherland, Bob Taylor, and
MIT researcher Lawrence G. Roberts, of the importance of this networking
concept.
Leonard Kleinrock at MIT published
the first paper on packet switching theory in July 1961 and the first book on
the subject in 1964. Kleinrock convinced Roberts of the theoretical feasibility
of communications using packets rather than circuits, which was a major step
along the path towards computer networking. The other key step was to make the
computers talk together. To explore this, in 1965 working with Thomas Merrill,
Roberts connected the TX-2 computer in Mass. to the Q-32 in California with a
low speed dial-up telephone line creating the first (however small)
wide-area computer network ever built. The result of this experiment was the realization
that the time-shared computers could work well together, running programs and
retrieving data as necessary on the remote machine, but that the circuit
switched telephone system was totally inadequate for the job. Kleinrock's
conviction of the need for packet switching was confirmed.
In late 1966 Roberts went to DARPA
to develop the computer network concept and quickly put together his plan for
the "ARPANET", publishing it in 1967. At the conference where he
presented the paper, there was also a paper on a packet network concept from
the UK by Donald Davies and Roger Scantlebury of NPL. Scantlebury told Roberts
about the NPL work as well as that of Paul Baran and others at RAND. The RAND group had written a paper on packet switching networks for secure voice in
the military in 1964. It happened that the work at MIT (1961-1967), at RAND (1962-1965), and at NPL (1964-1967) had all proceeded in parallel without any of the
researchers knowing about the other work. The word "packet" was
adopted from the work at NPL and the proposed line speed to be used in the
ARPANET design was upgraded from 2.4 kbps to 50 kbps.
In August 1968, after Roberts and
the DARPA funded community had refined the overall structure and specifications
for the ARPANET, an RFQ was released by DARPA for the development of one of the
key components, the packet switches called Interface Message Processors
(IMP's). The RFQ was won in December 1968 by a group headed by Frank Heart at
Bolt Beranek and Newman (BBN). As the BBN team worked on the IMP's with Bob
Kahn playing a major role in the overall ARPANET architectural design, the
network topology and economics were designed and optimized by Roberts working
with Howard Frank and his team at Network Analysis Corporation, and the network
measurement system was prepared by Kleinrock's team at UCLA.
Due to Kleinrock's early development
of packet switching theory and his focus on analysis, design and measurement,
his Network Measurement Center at UCLA was selected to be the first node on the
ARPANET. All this came together in September 1969 when BBN installed the first
IMP at UCLA and the first host computer was connected. Doug Engelbart's project
on "Augmentation of Human Intellect" (which included NLS, an early
hypertext system) at Stanford Research Institute (SRI) provided a second node.
SRI supported the Network Information Center, led by Elizabeth (Jake) Feinler
and including functions such as maintaining tables of host name to address
mapping as well as a directory of the RFC's. One month later, when SRI was
connected to the ARPANET, the first host-to-host message was sent from
Kleinrock's laboratory to SRI. Two more nodes were added at UC Santa Barbara
and University of Utah. These last two nodes incorporated application
visualization projects, with Glen Culler and Burton Fried at UCSB investigating
methods for display of mathematical functions using storage displays to deal
with the problem of refresh over the net, and Robert Taylor and Ivan Sutherland
at Utah investigating methods of 3-D representations over the net. Thus, by the
end of 1969, four host computers were connected together into the initial
ARPANET, and the budding Internet was off the ground. Even at this early stage,
it should be noted that the networking research incorporated both work on the
underlying network and work on how to utilize the network. This tradition
continues to this day.
Computers were added quickly to the
ARPANET during the following years, and work proceeded on completing a functionally
complete Host-to-Host protocol and other network software. In December 1970 the
Network Working Group (NWG) working under S. Crocker finished the initial
ARPANET Host-to-Host protocol, called the Network Control Protocol (NCP). As
the ARPANET sites completed implementing NCP during the period 1971-1972, the
network users finally could begin to develop applications.
In October 1972 Kahn organized a
large, very successful demonstration of the ARPANET at the International
Computer Communication Conference (ICCC). This was the first public
demonstration of this new network technology to the public. It was also in 1972
that the initial "hot" application, electronic mail, was introduced.
In March Ray Tomlinson at BBN wrote the basic email message send and read
software, motivated by the need of the ARPANET developers for an easy
coordination mechanism. In July, Roberts expanded its utility by writing the
first email utility program to list, selectively read, file, forward, and
respond to messages. From there email took off as the largest network
application for over a decade. This was a harbinger of the kind of activity we
see on the World Wide Web today, namely, the enormous growth of all kinds of
"people-to-people" traffic.
НОВОСТИ
ВХОД
ТЕГИ
Рефераты бесплатно, курсовые, дипломы, научные работы, реферат бесплатно, сочинения, курсовые работы, реферат, доклады, рефераты, рефераты скачать, рефераты на тему и многое другое.