11 June 2009
Author: Charalambos SivridisThe Origin Of Internet
Darpanet and the origin of internet
Cold war era...
Do you really now the origin of the internet? Well the story begins way back, at the beginning of the cold war era! The general accepted (perhaps unofficial) story is that after ?1962 Cuban missile crisis? someone in the US DoD (United States Department of Defense) had the idea of a durable computer network that can survive even a nuclear attack, at that time ?Northwww.norad.mil) had implemented for the US Air Force a new defense system the ?Semi Automatic Ground Environment? (or SAGE). The SAGE project became operational in January 1959 and was fully functional in 1963 with 3 combat centers, 24 direction centers and over 100 long distance radars. SAGE sites were connected to multiple radar stations which transmitted digital tracking data by modem over ordinary telephone lines or radio signals. The early warning, tracking and intercepting capability for long range bombers was the main target of the system and that was succeeded. Although a few years later the Soviets started deploying ?intercontinental ballistic missiles? (or ICBM) and new types of submarine launched ballistic missiles (or SLBM). The SAGE project was never designed to counter long range missiles so it became obsolete quite quickly although it was still operational until 1983. You may think why I am writing all this? well the SAGE project was the first national real computer network! But there was a small problem. Until then, the main idea behind computer network was that it had to be centralized, but that was unacceptable if you wanted a network that will still keep going after several or maybe most of the network servers ?down?. So a new decentralized form of network was a necessity but actually that was not yet invented...
Paul Baran and the RAND Co.
Paul Baran a young engineer working for the RAND Co. first developed the concept of packet switching (he used the term ?message blocks?) in distributed networks during his research for the SAGE project, first his results were presented to the US Air force possibly in 1961. His work was accepted by the US Air Force and DoD for implementation and further testing. Baran had also published a series of ?RAND studies? between 1960 and 1962 and finally eleven papers titled "On Distributed Communications," in 1964. (RAND Co. together with IBM were involved in the development for the SAGE program)
Baran's study describes a new architecture of a distributed packet switched communications network with no central control. The network was designed to withstand massive destruction to individual components without loosing communication. The basic concept is that every computer will be connected to one or more other computers with no central control. The network was actually designed to survive a nuclear conflict and basic assumption was that the network links could fail at any time. Baran?s study made its way to Robert Taylor and J.C.R. Licklider at the ARPA IPTO (Information Processing Techniques Office http://www.darpa.mil/ipto/), by that time they were also thinking to build a wide area communications network. Baran's 1964 series of papers also influenced Lawrence Roberts and Kleinrock to adopt this technology for the development of a new network (ARPANET) a few years later.
ARPA and the creation of ARPANET
In 1958 the US DoD created an organization called "Advanced Research Projects Agency" or ARPA for short. ARPA was supposed to be a direct response to the Soviet launching of Sputnik in 1957, with mission to keep U.S. military technology as high as possible. ARPA renamed to DARPA in 1972 (Defense Advanced Research Projects Agency), the mission of the agency as written to the official site is "to maintain the technological superiority of the U.S. military and prevent technological surprise from harming our national security by sponsoring revolutionary, high-payoff research bridging the gap between fundamental discoveries and their military use."
One of the many projects involved with ARPA was the ARPANET. The Advanced Research Projects Agency Network was the first real packet switching computer network. But why and how was it created? In 1969 the US DoD funded ARPA to build a network primarily for the communication between defense contractors and universities doing hi-tech military research. The main idea was that the network will work with packet switching technology, based on RAND Co. packet switching distributed network research(Paul Baran?s work), as a means of ensuring failure resistant communications. Basically the ARPANET was never intended to be a ?next day? survivable communications network but the robust structure of a packet switched network that uses link-state routing protocols is part from the research done to develop a network that could survive a nuclear attack.
From ARPANET to CSNET to NSFNET to? today!
The contract for the construction of ARPANET was granted to BBN Technologies on April 1969 and by November the first permanent ARPANET link was established (UCLA with SRI). BBN Technologies design was actually as Robert Taylor has proposed; the main structure of the network was composed of small computers. The computers were called Interface Message Processors (or IMP), the main function of each one was to operate as a router. The IMPs were connected to each other ?24/7? using modems. (That sounds very familiar...)
The first message sent over ?host to host connection? through the ARPANET was from a programmer C.Kline on October 1969 the message was the word ?login? but the system only transmitted ?lo? and then crashed! The ARPANET grew really fast from 2 IMPs by November 1969 and 40 by September 1973 to hundreds in 1981. In 1983 the ARPANET was demilitarized and the US military portion moved to a new network the MILNET.
In the early 80s some Universities had access to the ARPANET but not all of them, in fact many wanted to have access to ARPANET and that was a problem, so the US National Science Foundation funded a new network the CSNET (Computer Science Network). Four Institutions were involved in the project, University of Wisconsin, University of Delaware, Purdue University and the RAND Co. CSNET connected to ARPANET with TCP/IP over X.25 ITU-T standard protocol. CSNET was actually more or less extension of the ARPANET and kept in use until 1989.
Just for the history the TCP/IP protocol was first deployed in the ARPANET in 1983 replacing the older NCP protocol (Network Control Program). In the beginning of the ARPANET the protocol used was the 1822 which was highly reliable for host to host communication but it was problematic for other applications.
While CSNET was growing NSF (www.nsf.gov) began funding the creation of NSFNET. NSF wanted a new ultra fast network able to move data more than twenty-five times the speed of CSNET connecting existing regional networks and local academic networks to ARPANET. NSFNET started in 1986 with connections among five universities (Princeton University, University of California at San Diego, University of Illinois, Cornell University and the Pittsburgh Supercomputing Center). Its connection with ARPANET immediately put NSFNET into the major leagues as far as networking was concerned. NSFNET was decided to be open to the academic community while the other wide-area networks (all government-owned) supported mere handfuls of specialized contractors and researchers. The flow of traffic on NSFNET was huge and from the first year an upgrade was required. The opening of the network to commercial interests began in 1988 when the US Federal Networking Council approved the interconnection of the NSFNET with other commercial services.
At the beginning of the 90s everything was in place but something still was missing for the Internet to reach today?s popularity. This time a European project from the CERN organization (www.cern.ch ) called World Wide Web came along. WWW actually made easy for a user with a ?Web browser? to see text pictures or video in a Web page via the Internet. It is a fact that the infrastructure existed but it was actually the WWW project that boosted the spread of information through the Internet combined with an easy to use interface. Since 1993 CERN announced that the WWW will be free of charge and in my personal opinion a great indirect help was given also form the GNU project (www.gnu.org ) since high quality free software was and is of course available for everyone to build his personal Web Server. Now combine free software and fast 24/7 telephone high speed connections and you can imagine the everyday rapid growth of the Internet...