The Advanced Research Projects Agency Network (ARPANET) of the U.S. Department of Defense was the world's first operational packet switching network, and the progenitor of the global Internet. Packet switching, now the dominant basis for both data and voice communication worldwide, was a new and important concept in data communications. Previously, data communications was based on the idea of circuit switching, as in the old typical telephone circuit, where a dedicated circuit is tied up for the duration of the call and communication is only possible with the single party on the other end of the circuit. With packet switching, a system could use one communication link to communicate with more than one machine by assembling data into packets. Not only could the link be shared (much as a single mailbox can be used to post letters to different destinations), but each packet could be routed independently of other packets. This was a big breakthrough. ==Background of the ARPANET== The earliest ideas of a computer network intended to allow general communication between users of various computers were formulated by J.C.R. Licklider of MIT in August 1962, in a series of memos discussing his "Galactic Network" concept. These ideas contained almost everything that the Internet is today. In October 1962, Licklider was appointed head of the Behavioral Sciences and Command and Control programs at Advanced Research Projects Agency (as it was then called), the United States Department of Defense Advanced Research Projects Agency. He would then convince Ivan Sutherland and Robert Taylor (computer scientist) that this was a very important concept, although he left ARPA before any actual work on his vision was performed. Separately, Paul Baran had started work in 1959 at the RAND on secure communications technologies that could enable a military communications network to withstand a nuclear weapon. His results, published in a series of studies starting in 1960, described two key ideas: first, use of a decentralized network with multiple paths between any two points; and second, dividing complete user messages into what he called ''message blocks'' before sending them into the network. This first allowed the elimination of single points of failure, and enabled the network to automatically and efficiently work around any failures. A summary paper describing the entire scheme was presented in 1962, and published in 1964. At about the same time, Leonard Kleinrock had performed early work on store and forward message systems for his doctoral thesis at MIT. This resulted in a very important analysis covering queueing theory in store and forward networks, eventually published as a book in 1964. However, this work did not include the concept of breaking a user's message up into smaller units for transmission through the network. Kleinrock describes his work as: : "''Basically, what I did for my PhD research in 1961-1962 was to establish a mathematical theory of packet networks ..''" Finally, Donald Davies of National Physical Laboratory had begun working with related concepts in 1965, after a conference in the United Kingdom on time-sharing brought up the inadequacies of existing circuit switching networks. His work was originally carried out independently from Baran's work, although Davies learned of it after he gave a seminar on his ideas at NPL in 1966; incidentally, it was Davies who introduced the term ''packet''. Thus, the ideas that were to become the ARPANET came from four independent research centers: DARPA, the RAND corporation, MIT, and NPL (in the UK). ==Origins of the ARPANET== While all this was happening, ARPA and Taylor continued to be interested in creating a computer communication network, in part to allow ARPA-sponsored researchers in various locations to use various computers which ARPA was providing, and in part to quickly make new software and other results widely available. At the end of 1966, Taylor brought Lawrence G. Roberts to ARPA from MIT Lincoln Laboratory to head a project to create the network; Roberts had previously encountered Davies at the time-sharing conference. Roberts' initial concept was to hook the various time-sharing machines directly to each other, through telephone lines. At an early meeting in 1967, many of the participants were unenthusiastic at having the load of managing this line put directly on their computer. One of the participants, Wesley A. Clark, came up with the idea of using separate smaller computers to manage the communication links; the small computers would then be connected to the large time-sharing main-frame computers. Initial planning for the ARPANET began on that basis. Roberts then proceeded to author a "plan for the ARPANET", which was presented at a symposium in 1967; also presenting there was Roger Scantlebury, from Davies' group at NPL. He discussed packet switching with Roberts, and introduced Roberts to Baran's work. The exact impact is unclear, but Roberts' plans for the network were soon modified after his meeting with Scantlebury. ==Creation of the ARPANET== By the summer of 1968, a complete plan had been prepared, and after approval at ARPA, a Request For Quotation (RFQ) was sent to 140 potential bidders. Most regarded the proposal as outlandish, and only 12 companies submitted bids, of which only four were regarded as in the top rank. By the end of the year, the field had been narrowed to two, and after negotiations, a final choice was made, and the contract was awarded to Bolt, Beranek and Newman (BBN) early in 1969 (see: 7 April 1969 and Request for Comments). The entire system, including both hardware and the world's first router software, was designed and installed in nine months. ==Initial ARPANET deployment== To the right is the record of the first message ever sent over the ARPANET; it took place at 10:30PM on October 29, 1969. This record is an excerpt from the "IMP Log" kept at UCLA, and describes setting up a message transmission to go from the UCLA SDS Sigma 7 Host computer to the SRI SDS 940 Host computer. The initial ARPANET consisted of four nodes; each was a small computer known as an Interface Message Processor or IMP (the concept suggested by Wesley Clark). The IMPs at each site performed the function of a router, and were connected to each other using 56 kbit/second digital links over leased lines. The first four were installed at UCLA's SDS SIGMA 7 computer (where Kleinrock had established a Network Measurement Center), the Stanford Research Institute SDS 940 computer (named 'Genie', where Doug Engelbart had created "NLS_(computer_system) ," an early hypertext system), University of California, Santa Barbara's IBM 360/75, and University of Utah's DEC PDP-10 running TENEX. The first ARPANET link was established on November 21 1969, between an IMP at UCLA and another at SRI's Augmentation Research Center. By December 5, 1969, the entire 4-node network was connected. In 1972, Ray Tomlinson of BBN invented email, and the first computer chat connects two AI programs, Parry at Stanford with DOCTOR at BBN. By 1973, the File Transfer Protocol (File_Transfer_Protocol) and Network Voice Protocol (NVP) specifications had been defined (RFC 741) and then implemented, enabling file transfers and conference calls over the ARPANET. At that point, 75% of the ARPANET traffic was email. In 1975, satellite links cross two oceans (to Hawaii and UK) as the first TCP tests are run over them by Stanford, BBN, and UCL, and in 1976 Elizabeth II, Queen of the United Kingdom, sends out the first royal email on 26 March from the Royal Signals and Radar Establishment (RSRE) in Malvern. ==ARPANET IMP Hardware== BBN chose a ruggedized version of Honeywell's DDP-516 computer to build the first generation Interface Message Processor (more commonly known as an IMP) to connect host computers to the ARPA network. The 516 was originally configured with 12KW of core memory (expandable) and a 16 channel Direct Multiplex Control (DMC) unit. Custom interfaces were used to connect, through the multiplexor, to each of the hosts and modems. In addition to the lamps on the front panel of the 516 there was also a special set of 24 indicator lights to show the status of the IMP communication channels. The IMP performed the function of a store and forward message switcher, the precursor to modern internet routers. Each IMP could support up to four local hosts and could communicate with up to six remote IMPs over 50 kbit/s leased lines. Support for 230.4 kbit/s circuits was added in 1970. In 1971 there was a transition to using the non-ruggedized H-316 as an IMP, but it could also be configured as a Terminal IMP (TIP) which added support for up to 63 Teletypes through a multi-line controller. The 316 featured a greater degree of integration than the 516 which made it lighter, less expensive and easier to maintain. The 316 was configured with 20KW of core memory for a TIP. The size of core memory was increased to 16KW for the IMPs and 28KW for TIPs in 1973. The Honeywell based IMPs were superseded by multiprocessing BBN Pluribus IMPs in 1975. The original IMPs and TIPs were phased out after the introduction of the NSFNET, but some IMPs remained in service as late as 1989. ==The ARPANET and nuclear attacks== The Internet Society writes about the merger of technical ideas that produced the ARPANET in ''A Brief History of the Internet'', and states in a note: : It was from the RAND study that the false rumor started claiming that the ARPANET was somehow related to building a network resistant to nuclear war. This was never true of the ARPANET, only the unrelated RAND study on secure voice considered nuclear war. However, the later work on Internetting did emphasize robustness and survivability, including the capability to withstand losses of large portions of the underlying networks. The myth that the ARPANET was built to withstand nuclear attacks however remains such a strong and apparently appealing idea - and of course "a good story" - that many people refuse to believe it is not true. However it is ''not'', unless one means that these ideas influenced the ARPANET development by way of the RAND research papers. The ARPANET was designed to survive network losses, but the main reason was actually that the switching nodes and network links were not highly reliable, even without any nuclear attacks. ==Retrospective== Support and style of management by ARPA was crucial to the success of ARPANET. As the Internet develops and the struggle over the role the Internet plays unfolds, it will be important to remember how the network developed and the culture that it was connected with. (As a facilitator of communication, the culture of the Net is an important feature to acknowledge.) The ARPANET Completion Report, as published jointly by BBN and ARPA concludes by stating: : "...it is somewhat fitting to end on the note that the ARPANET program has had a strong and direct feedback into the support and strength of computer science, from which the network itself sprung." (Chapter III, pg.132, Section 2.3.4) In order to understand the wonder that the Internet, and various parts of the Net, represent, we need to understand why the ARPANET Completion report ends with the suggestion that the ARPANET is fundamentally connected to and born of computer science. ==See also== *History of the Internet ==Further reading== * Paul Baran, ''[http://www.rand.org/publications/RM/baran.list.html On Distributed Communications]'' * Paul Baran, ''On Distributed Communications Networks'' (IEEE Transactions on Communications Systems, March 1964) * Leonard Kleinrock, ''Communication Nets: Stochastic Message Flow and Design'' (McGraw-Hill, 1964) * Arthur Norberg, Judy E. O'Neill, ''Transforming Computer Technology: Information Processing for the Pentagon, 1962-1982'' (Johns Hopkins University, 1996) pp. 153-196 * ''A History of the ARPANET: The First Decade'' (Bolt, Beranek and Newman, 1981) * Katie Hafner, ''Where Wizards Stay Up Late'' (Simon and Schuster, 1996) * Feinler, E.; Postel, Jon B. ''ARPANET Protocol Handbook'' (Network Information Center, Menlo Park, 1978) * Peter H. Salus, "Casting the Net: from ARPANET to Internet and Beyond" (Addison-Wesley, 1995) ==External links== * [http://www.isoc.org/internet/history/brief.shtml The Internet Society History Page] * [http://www.computerhistory.org/exhibits/internet_history/ The Computer History Museum] Images and maps of ARPANET from 1964 onwards. * [http://som.csudh.edu/cis/lpress/history/arpamaps/ ARPANET Maps] 1967 to 1977 * [http://www.lk.cs.ucla.edu/first_words.html Personal anecdote of the first message ever sent over the ARPANET] Internet Telecommunications history DARPA
This is an intermediate state. Eventually the stuff about the invention of packet switching is going to get moved to the packet switching page (just as some of this was moved here from the History of the Internet page), and more about the history of the ARPANet is going to get added here, as I have time to write it.. This is an improvement on what used to be here, though. User:Jnc 08:07, 24 Aug 2003 (UTC) ---- Not sure where to put this (from November 21 and 1969): :The first ARPANET link is established. --User:Maveric149 05:54, 22 Nov 2003 (UTC)~ :I've expanded it. == Data rate == I'm not sure about the nearby material that says they were connected "using modems": I think the link speeds were of the order of 56k, and the modems of that era were not even remotely near that speed (think 1200 bps): the links were more probably DS0 leased lines. -- User:The Anome 09:25, 6 Feb 2004 (UTC) : No, "modem" is right - that's a generic term for a device ("modulator - demodulator") that transforms a signal in one form (in this case, a bit stream) into another form (analog signals in this case). The ARPANet modems were provided by ATT; BBN's hardware only included the high-speed serial interfaces. The lines were indeed leased special high-bandwidth lines (but I don't think the concept "DS0" existed back then), again, provided by AT&T. User:Jnc 20:24, 1 Mar 2004 (UTC) : PS: When I said "high-bandwidth", I meant it in the technical sense (i.e. high band-pass), not as a synonym for "high bit rate" (although of course with the former it's easy to provide the latter). User:Jnc 21:10, 1 Mar 2004 (UTC) According to [http://www.2sparrows.org/Sean/rit/t1e1.htm] "The T1 standard was developed in the United States in the early 1960's." This [http://www.privateline.com/TelephoneHistory4/History4.htm] says "Also in 1963 digital carrier techniques were introduced. [...] T1 quickly became the backbone of long distance toll service and then the primary handler of local transmission between central offices." So it's quite plausible that the circuit was part of a then-existing digital trunk system. However, it would be nice to have a reference which can settle this one way or another. -- User:The Anome 12:39, 27 Sep 2004 (UTC) [http://groups.google.com/groups?q=arpanet+data+links&start=10&hl=en&lr=&ie=UTF-8&client=firefox-a&selm=telecom12.891.1%40eecs.nwu.edu&rnum=16] describes original link speeds as having been 56k. For 1960s modems, even 600 bps over an end-to-end analog connection was "high speed". The nearest other possible solution were the FDM interleaving solutions. But why would anyone install this, when T1 was commercially available from 1962 onwards? Allowing for bit-robbing, a single DS0 demultiplexed from a T1 would be 56k, exactly the data rates quoted in the source. -- User:The Anome 12:57, 27 Sep 2004 (UTC) Phil Karn also says here [http://groups.google.com/groups?q=arpanet+data+links&start=20&hl=en&lr=&ie=UTF-8&client=firefox-a&selm=1990Jul24.190156.12202%40bellcore-2.bellcore.com&rnum=28] that "Actually, the ARPANET backbone links were almost all 56kb/s." -- User:The Anome 13:05, 27 Sep 2004 (UTC) : I simply don't know the details of how AT+T provided the bandwidth. It may well have been a breakout of a T1 line. I have looked through everything I have, and nothing says anything about it. I do know (from the BBN proposal, in response to the original ARPA ARPANET RFP) that the interface between the IMP and modem was two wires in each direction - a data line and a clock line. So I guess the bit recovery was done by the AT+T gear - maybe, because for all I know AT+T just carried those two signals through from one end to the other, mostly unchanged, and didn't do clock recovery at the far end of each link. Turning the bit stream into packets (framing - i.e. figuring out where the byte boundaries was, and then turning the byte stream into packets) was done by the BBN hardware in the IMPs. The AT+T "modems" (they didn't do everything we now think of modems as doing) were huge - at MIT (which had two AT+T lines early on, when I first became responsible for the IMPs at MIT, and a third later on) the AT+T gear was in a giant rack (about 6' high, and 2.5' square, which was mostly full of stuff). My ''guess'' would be that the bandwidth was provided in different ways, at different times and on different links, but that is just a guess. Sorry I can't help more - that's all I know and/or can find out. User:Jnc User_talk:Jnc 04:38, 11 Nov 2004 (UTC) ==Wesley Clark== Well, there are a zillion links to Wesley Clark, and almost certainly all of them mean the general. So although I'd ''like'' to make it a disambig page, and then have separate pages for the general and the computer scientist, it's probably too much work to be worth it. If I can figure out the computer scientist's middle name, we can put his page under that (or. more likely, his initial), with a note somewhere on the main Wesley Clark page to refer to it. User:Jnc 17:04, 21 Mar 2004 (UTC) : I believe the MIT Wesley Clark you wish to disambiguate is Wesley A. Clark, as referenced here: [http://history.nih.gov/exhibits/linc/docs/page_10.html Participants in the LINC Evaluation Program] -- User:Tracy Rowell 10:25, 27 Sep 2004 (UTC) : Oooh, thanks for dredging that up! User:Jnc User_talk:Jnc 12:00, 8 Dec 2004 (UTC) == images? == [[Image:First-arpanet-imp-log.jpg|thumb|250px|left|first ARPANET imp log. ''source:''The Computer History Museum ([http://www.computerhistory.org/copyright/ fair use])]] [[Image:Arpnet-map-march-1977.png|thumb|250px|ARPANET logical map circa 1977. ''source:''The Computer History Museum ([http://www.computerhistory.org/copyright/ fair use])]] == Leonard Kleinrock == I e-mailed Leonard and he outlined that the following was incorrect in the ((cur) (last) 08:23, 4 Nov 2004 Jumbuck m (robot Adding:id)) entry: This is what was originally in the entry: "Leonard Kleinrock had performed tests on store and forward message systems in 1961, and wrote a very important book in 1964 covering queueing theory and routing in store and forward networks, although this work did not include the concept of breaking a user's message up into smaller units for transmission through the network." Leonard wrote to me with the following: : Dear Kim, : ... : This is not true. In fact, in my July 1962 publication (see my website: www.lk.cs.ucla.edu) I talk about chopping messages into fixed length units and transmitting them separately over the link. That material also appeared in my December 1962 PhD Dissertation which was later published as the book that is quoted, "Communication Nets"; you can easily find the description in that book in Section 5.3. Importantly, you should note that my July 1962 publication was months ahead of Paul Baran's and years ahead of anything that Donald Davies did. Basically, what I did for my PhD research in 1961-1962 was to establish a mathematical theory of packet networks which uncovered the underlying principles that drives today's Internet. : I would appreciate it if you would correct the entry in that link. : Best of luck. Len Kleinrock I have updated the page accordingly. However there does seem to be some dispute - so I would like updaters to consult with Lenoard Kleirock before making changes his e-mail address is at www.lk.cs.ucla.edu - it would be even better if we could get Paul Baran and Donalad Davies in the dialog to thrash this out amongst themselves - they could then propose a nice summary that would sort out any inconsistencies - So whoever wants to take this on please be my guest! -- User:Kim Meyrick 21:44, 10 Nov 2004 : You need to be careful with Kleinrock's claims, because he has an axe to grind. If you read Baran's [http://www.rand.org/about/history/baran.html page], which I find to be equally incorrect, Baran claims all the credit. Alas, to talk to Donald Davies, you'll need a spirit medium, because he is no longer with us. Before he died, he ''did'' dispute Kleinrock's claim. And, needless to say, if you think Baran and Kleinrock are going to agree on a division of the credit, well... : As to the 1964 book, here's what section 5.3 says: :: "The server picks the next message in the queue and performs one unit of service upon it (i.e. services this message for exactly Q seconds). At the end of this time interval, the message leaves the system if its service (transmission) is finished; if not, it joins the end of the queue with its service partially completed .." : And that is the entirety of what the book says about the topic. Although no details at all are given, the most plausible reading of what was meant is that some kind of link-local fragmentation/reassembly is being used, not end-end packets of the sort described in Baran's work, and now used in the Internet. : I have the 1961 PhD proposal, and I'll look at that now. However, I suggest you be wary about rushing in where angels fear to tread! I would have to go check Hafner's book, but my ''vague'' recollection is that she got it about right. User:Jnc User_talk:Jnc 02:13, 11 Nov 2004 (UTC) :: I have now checked both the 1961 thesis proposal, and the 1962 RLE QTR - the former says nothing at all, and the latter has exactly the same language as the book (quoted above). It's worth noting that the book is basically entirely about queueing theory, and is not about engineering a data communication network. The examples given in the book are principally telegram networks, although trucking networks also figure in some cases. :: I also checked Hafner's book, and she doesn't explicitly rate Kleinrock's contribution, although she implicitly seems to credit Baran and Davies with a key role in coming up with the idea of packet data networks. I think there's something in that - they definitely were thinking of practical data communication systems, whereas Kleinrock's work is very much focused on the theory of queueing, which obviously has a much wider application than just packet networks. And of course Licklider and Taylor were the people who actually had the vision to build a real network. User:Jnc User_talk:Jnc 04:10, 11 Nov 2004 (UTC) : PS: DARPA's own history of the ARPANet (see article) nowhere mentions Kleinrock's work as a source of inspiration - but does prominently cite Baran and Davies. Not that I wholly believe that ''either'' (I think Roberts' quote about relying on Kleinrock's work is probably accurate), but more to show you that the picture painted by Kleinrock is not universally shared, and that you shouldn't rely on any one source. See also my recent comments at Talk:Packet switching on the subject of Kleinrock's proper share of the credit. User:Jnc User_talk:Jnc 02:44, 11 Nov 2004 (UTC) Leonard Kleinrock has responded with the following which i post on his behalf: "Both comments by jnc miss the point. I was not suggesting that others not be mentioned. In fact, I include the contributions of Baran and Davies in every presentation I make regarding the history of the Internet Jnc's referral to bogus claims is amazing! It may be that he has not looked at the source documents. Anyone familiar with those documents would be able to provide a more balanced view of the early work than he has articluted." -- User:Kim Meyrick 18:00, 12 Nov 2004 : I had to laugh at "I include the contributions of Baran and Davies in every presentation I make regarding the history of the Internet". If you look at every page he has linked to from his "The History of the Internet" links [http://www.lk.cs.ucla.edu/internet_history.html page], most of which he wrote, you will not find a single instance of Baran's name, and Davies is only mentioned once, as the originator of the term "packet". : I don't know which documents he is speaking of - I have read all the ones he has posted, and a great number more besides (although I don't have access to RAND's working papers, or the internal archives of DARPA). If he has more original, contemporary documents he'd like to post, I'd be happy to review them. User:Jnc User_talk:Jnc 22:41, 12 Nov 2004 (UTC) ==Date clash== Ah, the joys of people adding stuff to articles piece-meal. At ARPANET#Initial ARPANET deployment it says: : the first message ever sent over the ARPANET; it took place at 22:30PM on October 29, 1969. and then later on it says: : The first ARPANET link was established on November 21, 1969, between an IMP at UCLA and another at SRI's So how could a message have been sent on Oct 29 when the first link allegedly wasn't there until November 21? Alas, I don't have the time right now to ressarch this: can someone else straighten this out? User:Jnc User_talk:Jnc 00:41, 6 Jan 2005 (UTC)
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The Advanced Research Projects Agency Network (ARPANET) of the U.S. Department of Defense was the world's first operational packet switching network, and the progenitor of the global Internet. Packet switching, now the dominant basis for both data and voice communication worldwide, was a new and important concept in data communications. Previously, data communications was based on the idea of circuit switching, as in the old typical telephone circuit, where a dedicated circuit is tied up for the duration of the call and communication is only possible with the single party on the other end of the circuit. With packet switching, a system could use one communication link to communicate with more than one machine by assembling data into packets. Not only could the link be shared (much as a single mailbox can be used to post letters to different destinations), but each packet could be routed independently of other packets. This was a big breakthrough. ==Background of the ARPANET== The earliest ideas of a computer network intended to allow general communication between users of various computers were formulated by J.C.R. Licklider of MIT in August 1962, in a series of memos discussing his "Galactic Network" concept. These ideas contained almost everything that the Internet is today. In October 1962, Licklider was appointed head of the Behavioral Sciences and Command and Control programs at Advanced Research Projects Agency (as it was then called), the United States Department of Defense Advanced Research Projects Agency. He would then convince Ivan Sutherland and Robert Taylor (computer scientist) that this was a very important concept, although he left ARPA before any actual work on his vision was performed. Separately, Paul Baran had started work in 1959 at the RAND on secure communications technologies that could enable a military communications network to withstand a nuclear weapon. His results, published in a series of studies starting in 1960, described two key ideas: first, use of a decentralized network with multiple paths between any two points; and second, dividing complete user messages into what he called ''message blocks'' before sending them into the network. This first allowed the elimination of single points of failure, and enabled the network to automatically and efficiently work around any failures. A summary paper describing the entire scheme was presented in 1962, and published in 1964. At about the same time, Leonard Kleinrock had performed early work on store and forward message systems for his doctoral thesis at MIT. This resulted in a very important analysis covering queueing theory in store and forward networks, eventually published as a book in 1964. However, this work did not include the concept of breaking a user's message up into smaller units for transmission through the network. Kleinrock describes his work as: : "''Basically, what I did for my PhD research in 1961-1962 was to establish a mathematical theory of packet networks ..''" Finally, Donald Davies of National Physical Laboratory had begun working with related concepts in 1965, after a conference in the United Kingdom on time-sharing brought up the inadequacies of existing circuit switching networks. His work was originally carried out independently from Baran's work, although Davies learned of it after he gave a seminar on his ideas at NPL in 1966; incidentally, it was Davies who introduced the term ''packet''. Thus, the ideas that were to become the ARPANET came from four independent research centers: DARPA, the RAND corporation, MIT, and NPL (in the UK). ==Origins of the ARPANET== While all this was happening, ARPA and Taylor continued to be interested in creating a computer communication network, in part to allow ARPA-sponsored researchers in various locations to use various computers which ARPA was providing, and in part to quickly make new software and other results widely available. At the end of 1966, Taylor brought Lawrence G. Roberts to ARPA from MIT Lincoln Laboratory to head a project to create the network; Roberts had previously encountered Davies at the time-sharing conference. Roberts' initial concept was to hook the various time-sharing machines directly to each other, through telephone lines. At an early meeting in 1967, many of the participants were unenthusiastic at having the load of managing this line put directly on their computer. One of the participants, Wesley A. Clark, came up with the idea of using separate smaller computers to manage the communication links; the small computers would then be connected to the large time-sharing main-frame computers. Initial planning for the ARPANET began on that basis. Roberts then proceeded to author a "plan for the ARPANET", which was presented at a symposium in 1967; also presenting there was Roger Scantlebury, from Davies' group at NPL. He discussed packet switching with Roberts, and introduced Roberts to Baran's work. The exact impact is unclear, but Roberts' plans for the network were soon modified after his meeting with Scantlebury. ==Creation of the ARPANET== By the summer of 1968, a complete plan had been prepared, and after approval at ARPA, a Request For Quotation (RFQ) was sent to 140 potential bidders. Most regarded the proposal as outlandish, and only 12 companies submitted bids, of which only four were regarded as in the top rank. By the end of the year, the field had been narrowed to two, and after negotiations, a final choice was made, and the contract was awarded to Bolt, Beranek and Newman (BBN) early in 1969 (see: 7 April 1969 and Request for Comments). The entire system, including both hardware and the world's first router software, was designed and installed in nine months. ==Initial ARPANET deployment== To the right is the record of the first message ever sent over the ARPANET; it took place at 10:30PM on October 29, 1969. This record is an excerpt from the "IMP Log" kept at UCLA, and describes setting up a message transmission to go from the UCLA SDS Sigma 7 Host computer to the SRI SDS 940 Host computer. The initial ARPANET consisted of four nodes; each was a small computer known as an Interface Message Processor or IMP (the concept suggested by Wesley Clark). The IMPs at each site performed the function of a router, and were connected to each other using 56 kbit/second digital links over leased lines. The first four were installed at UCLA's SDS SIGMA 7 computer (where Kleinrock had established a Network Measurement Center), the Stanford Research Institute SDS 940 computer (named 'Genie', where Doug Engelbart had created "NLS_(computer_system) ," an early hypertext system), University of California, Santa Barbara's IBM 360/75, and University of Utah's DEC PDP-10 running TENEX. The first ARPANET link was established on November 21 1969, between an IMP at UCLA and another at SRI's Augmentation Research Center. By December 5, 1969, the entire 4-node network was connected. In 1972, Ray Tomlinson of BBN invented email, and the first computer chat connects two AI programs, Parry at Stanford with DOCTOR at BBN. By 1973, the File Transfer Protocol (File_Transfer_Protocol) and Network Voice Protocol (NVP) specifications had been defined (RFC 741) and then implemented, enabling file transfers and conference calls over the ARPANET. At that point, 75% of the ARPANET traffic was email. In 1975, satellite links cross two oceans (to Hawaii and UK) as the first TCP tests are run over them by Stanford, BBN, and UCL, and in 1976 Elizabeth II, Queen of the United Kingdom, sends out the first royal email on 26 March from the Royal Signals and Radar Establishment (RSRE) in Malvern. ==ARPANET IMP Hardware== BBN chose a ruggedized version of Honeywell's DDP-516 computer to build the first generation Interface Message Processor (more commonly known as an IMP) to connect host computers to the ARPA network. The 516 was originally configured with 12KW of core memory (expandable) and a 16 channel Direct Multiplex Control (DMC) unit. Custom interfaces were used to connect, through the multiplexor, to each of the hosts and modems. In addition to the lamps on the front panel of the 516 there was also a special set of 24 indicator lights to show the status of the IMP communication channels. The IMP performed the function of a store and forward message switcher, the precursor to modern internet routers. Each IMP could support up to four local hosts and could communicate with up to six remote IMPs over 50 kbit/s leased lines. Support for 230.4 kbit/s circuits was added in 1970. In 1971 there was a transition to using the non-ruggedized H-316 as an IMP, but it could also be configured as a Terminal IMP (TIP) which added support for up to 63 Teletypes through a multi-line controller. The 316 featured a greater degree of integration than the 516 which made it lighter, less expensive and easier to maintain. The 316 was configured with 20KW of core memory for a TIP. The size of core memory was increased to 16KW for the IMPs and 28KW for TIPs in 1973. The Honeywell based IMPs were superseded by multiprocessing BBN Pluribus IMPs in 1975. The original IMPs and TIPs were phased out after the introduction of the NSFNET, but some IMPs remained in service as late as 1989. ==The ARPANET and nuclear attacks== The Internet Society writes about the merger of technical ideas that produced the ARPANET in ''A Brief History of the Internet'', and states in a note: : It was from the RAND study that the false rumor started claiming that the ARPANET was somehow related to building a network resistant to nuclear war. This was never true of the ARPANET, only the unrelated RAND study on secure voice considered nuclear war. However, the later work on Internetting did emphasize robustness and survivability, including the capability to withstand losses of large portions of the underlying networks. The myth that the ARPANET was built to withstand nuclear attacks however remains such a strong and apparently appealing idea - and of course "a good story" - that many people refuse to believe it is not true. However it is ''not'', unless one means that these ideas influenced the ARPANET development by way of the RAND research papers. The ARPANET was designed to survive network losses, but the main reason was actually that the switching nodes and network links were not highly reliable, even without any nuclear attacks. ==Retrospective== Support and style of management by ARPA was crucial to the success of ARPANET. As the Internet develops and the struggle over the role the Internet plays unfolds, it will be important to remember how the network developed and the culture that it was connected with. (As a facilitator of communication, the culture of the Net is an important feature to acknowledge.) The ARPANET Completion Report, as published jointly by BBN and ARPA concludes by stating: : "...it is somewhat fitting to end on the note that the ARPANET program has had a strong and direct feedback into the support and strength of computer science, from which the network itself sprung." (Chapter III, pg.132, Section 2.3.4) In order to understand the wonder that the Internet, and various parts of the Net, represent, we need to understand why the ARPANET Completion report ends with the suggestion that the ARPANET is fundamentally connected to and born of computer science. ==See also== *History of the Internet ==Further reading== * Paul Baran, ''[http://www.rand.org/publications/RM/baran.list.html On Distributed Communications]'' * Paul Baran, ''On Distributed Communications Networks'' (IEEE Transactions on Communications Systems, March 1964) * Leonard Kleinrock, ''Communication Nets: Stochastic Message Flow and Design'' (McGraw-Hill, 1964) * Arthur Norberg, Judy E. O'Neill, ''Transforming Computer Technology: Information Processing for the Pentagon, 1962-1982'' (Johns Hopkins University, 1996) pp. 153-196 * ''A History of the ARPANET: The First Decade'' (Bolt, Beranek and Newman, 1981) * Katie Hafner, ''Where Wizards Stay Up Late'' (Simon and Schuster, 1996) * Feinler, E.; Postel, Jon B. ''ARPANET Protocol Handbook'' (Network Information Center, Menlo Park, 1978) * Peter H. Salus, "Casting the Net: from ARPANET to Internet and Beyond" (Addison-Wesley, 1995) ==External links== * [http://www.isoc.org/internet/history/brief.shtml The Internet Society History Page] * [http://www.computerhistory.org/exhibits/internet_history/ The Computer History Museum] Images and maps of ARPANET from 1964 onwards. * [http://som.csudh.edu/cis/lpress/history/arpamaps/ ARPANET Maps] 1967 to 1977 * [http://www.lk.cs.ucla.edu/first_words.html Personal anecdote of the first message ever sent over the ARPANET] Internet Telecommunications history DARPA
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This is an intermediate state. Eventually the stuff about the invention of packet switching is going to get moved to the packet switching page (just as some of this was moved here from the History of the Internet page), and more about the history of the ARPANet is going to get added here, as I have time to write it.. This is an improvement on what used to be here, though. User:Jnc 08:07, 24 Aug 2003 (UTC) ---- Not sure where to put this (from November 21 and 1969): :The first ARPANET link is established. --User:Maveric149 05:54, 22 Nov 2003 (UTC)~ :I've expanded it. == Data rate == I'm not sure about the nearby material that says they were connected "using modems": I think the link speeds were of the order of 56k, and the modems of that era were not even remotely near that speed (think 1200 bps): the links were more probably DS0 leased lines. -- User:The Anome 09:25, 6 Feb 2004 (UTC) : No, "modem" is right - that's a generic term for a device ("modulator - demodulator") that transforms a signal in one form (in this case, a bit stream) into another form (analog signals in this case). The ARPANet modems were provided by ATT; BBN's hardware only included the high-speed serial interfaces. The lines were indeed leased special high-bandwidth lines (but I don't think the concept "DS0" existed back then), again, provided by AT&T. User:Jnc 20:24, 1 Mar 2004 (UTC) : PS: When I said "high-bandwidth", I meant it in the technical sense (i.e. high band-pass), not as a synonym for "high bit rate" (although of course with the former it's easy to provide the latter). User:Jnc 21:10, 1 Mar 2004 (UTC) According to [http://www.2sparrows.org/Sean/rit/t1e1.htm] "The T1 standard was developed in the United States in the early 1960's." This [http://www.privateline.com/TelephoneHistory4/History4.htm] says "Also in 1963 digital carrier techniques were introduced. [...] T1 quickly became the backbone of long distance toll service and then the primary handler of local transmission between central offices." So it's quite plausible that the circuit was part of a then-existing digital trunk system. However, it would be nice to have a reference which can settle this one way or another. -- User:The Anome 12:39, 27 Sep 2004 (UTC) [http://groups.google.com/groups?q=arpanet+data+links&start=10&hl=en&lr=&ie=UTF-8&client=firefox-a&selm=telecom12.891.1%40eecs.nwu.edu&rnum=16] describes original link speeds as having been 56k. For 1960s modems, even 600 bps over an end-to-end analog connection was "high speed". The nearest other possible solution were the FDM interleaving solutions. But why would anyone install this, when T1 was commercially available from 1962 onwards? Allowing for bit-robbing, a single DS0 demultiplexed from a T1 would be 56k, exactly the data rates quoted in the source. -- User:The Anome 12:57, 27 Sep 2004 (UTC) Phil Karn also says here [http://groups.google.com/groups?q=arpanet+data+links&start=20&hl=en&lr=&ie=UTF-8&client=firefox-a&selm=1990Jul24.190156.12202%40bellcore-2.bellcore.com&rnum=28] that "Actually, the ARPANET backbone links were almost all 56kb/s." -- User:The Anome 13:05, 27 Sep 2004 (UTC) : I simply don't know the details of how AT+T provided the bandwidth. It may well have been a breakout of a T1 line. I have looked through everything I have, and nothing says anything about it. I do know (from the BBN proposal, in response to the original ARPA ARPANET RFP) that the interface between the IMP and modem was two wires in each direction - a data line and a clock line. So I guess the bit recovery was done by the AT+T gear - maybe, because for all I know AT+T just carried those two signals through from one end to the other, mostly unchanged, and didn't do clock recovery at the far end of each link. Turning the bit stream into packets (framing - i.e. figuring out where the byte boundaries was, and then turning the byte stream into packets) was done by the BBN hardware in the IMPs. The AT+T "modems" (they didn't do everything we now think of modems as doing) were huge - at MIT (which had two AT+T lines early on, when I first became responsible for the IMPs at MIT, and a third later on) the AT+T gear was in a giant rack (about 6' high, and 2.5' square, which was mostly full of stuff). My ''guess'' would be that the bandwidth was provided in different ways, at different times and on different links, but that is just a guess. Sorry I can't help more - that's all I know and/or can find out. User:Jnc User_talk:Jnc 04:38, 11 Nov 2004 (UTC) ==Wesley Clark== Well, there are a zillion links to Wesley Clark, and almost certainly all of them mean the general. So although I'd ''like'' to make it a disambig page, and then have separate pages for the general and the computer scientist, it's probably too much work to be worth it. If I can figure out the computer scientist's middle name, we can put his page under that (or. more likely, his initial), with a note somewhere on the main Wesley Clark page to refer to it. User:Jnc 17:04, 21 Mar 2004 (UTC) : I believe the MIT Wesley Clark you wish to disambiguate is Wesley A. Clark, as referenced here: [http://history.nih.gov/exhibits/linc/docs/page_10.html Participants in the LINC Evaluation Program] -- User:Tracy Rowell 10:25, 27 Sep 2004 (UTC) : Oooh, thanks for dredging that up! User:Jnc User_talk:Jnc 12:00, 8 Dec 2004 (UTC) == images? == [[Image:First-arpanet-imp-log.jpg|thumb|250px|left|first ARPANET imp log. ''source:''The Computer History Museum ([http://www.computerhistory.org/copyright/ fair use])]] [[Image:Arpnet-map-march-1977.png|thumb|250px|ARPANET logical map circa 1977. ''source:''The Computer History Museum ([http://www.computerhistory.org/copyright/ fair use])]] == Leonard Kleinrock == I e-mailed Leonard and he outlined that the following was incorrect in the ((cur) (last) 08:23, 4 Nov 2004 Jumbuck m (robot Adding:id)) entry: This is what was originally in the entry: "Leonard Kleinrock had performed tests on store and forward message systems in 1961, and wrote a very important book in 1964 covering queueing theory and routing in store and forward networks, although this work did not include the concept of breaking a user's message up into smaller units for transmission through the network." Leonard wrote to me with the following: : Dear Kim, : ... : This is not true. In fact, in my July 1962 publication (see my website: www.lk.cs.ucla.edu) I talk about chopping messages into fixed length units and transmitting them separately over the link. That material also appeared in my December 1962 PhD Dissertation which was later published as the book that is quoted, "Communication Nets"; you can easily find the description in that book in Section 5.3. Importantly, you should note that my July 1962 publication was months ahead of Paul Baran's and years ahead of anything that Donald Davies did. Basically, what I did for my PhD research in 1961-1962 was to establish a mathematical theory of packet networks which uncovered the underlying principles that drives today's Internet. : I would appreciate it if you would correct the entry in that link. : Best of luck. Len Kleinrock I have updated the page accordingly. However there does seem to be some dispute - so I would like updaters to consult with Lenoard Kleirock before making changes his e-mail address is at www.lk.cs.ucla.edu - it would be even better if we could get Paul Baran and Donalad Davies in the dialog to thrash this out amongst themselves - they could then propose a nice summary that would sort out any inconsistencies - So whoever wants to take this on please be my guest! -- User:Kim Meyrick 21:44, 10 Nov 2004 : You need to be careful with Kleinrock's claims, because he has an axe to grind. If you read Baran's [http://www.rand.org/about/history/baran.html page], which I find to be equally incorrect, Baran claims all the credit. Alas, to talk to Donald Davies, you'll need a spirit medium, because he is no longer with us. Before he died, he ''did'' dispute Kleinrock's claim. And, needless to say, if you think Baran and Kleinrock are going to agree on a division of the credit, well... : As to the 1964 book, here's what section 5.3 says: :: "The server picks the next message in the queue and performs one unit of service upon it (i.e. services this message for exactly Q seconds). At the end of this time interval, the message leaves the system if its service (transmission) is finished; if not, it joins the end of the queue with its service partially completed .." : And that is the entirety of what the book says about the topic. Although no details at all are given, the most plausible reading of what was meant is that some kind of link-local fragmentation/reassembly is being used, not end-end packets of the sort described in Baran's work, and now used in the Internet. : I have the 1961 PhD proposal, and I'll look at that now. However, I suggest you be wary about rushing in where angels fear to tread! I would have to go check Hafner's book, but my ''vague'' recollection is that she got it about right. User:Jnc User_talk:Jnc 02:13, 11 Nov 2004 (UTC) :: I have now checked both the 1961 thesis proposal, and the 1962 RLE QTR - the former says nothing at all, and the latter has exactly the same language as the book (quoted above). It's worth noting that the book is basically entirely about queueing theory, and is not about engineering a data communication network. The examples given in the book are principally telegram networks, although trucking networks also figure in some cases. :: I also checked Hafner's book, and she doesn't explicitly rate Kleinrock's contribution, although she implicitly seems to credit Baran and Davies with a key role in coming up with the idea of packet data networks. I think there's something in that - they definitely were thinking of practical data communication systems, whereas Kleinrock's work is very much focused on the theory of queueing, which obviously has a much wider application than just packet networks. And of course Licklider and Taylor were the people who actually had the vision to build a real network. User:Jnc User_talk:Jnc 04:10, 11 Nov 2004 (UTC) : PS: DARPA's own history of the ARPANet (see article) nowhere mentions Kleinrock's work as a source of inspiration - but does prominently cite Baran and Davies. Not that I wholly believe that ''either'' (I think Roberts' quote about relying on Kleinrock's work is probably accurate), but more to show you that the picture painted by Kleinrock is not universally shared, and that you shouldn't rely on any one source. See also my recent comments at Talk:Packet switching on the subject of Kleinrock's proper share of the credit. User:Jnc User_talk:Jnc 02:44, 11 Nov 2004 (UTC) Leonard Kleinrock has responded with the following which i post on his behalf: "Both comments by jnc miss the point. I was not suggesting that others not be mentioned. In fact, I include the contributions of Baran and Davies in every presentation I make regarding the history of the Internet Jnc's referral to bogus claims is amazing! It may be that he has not looked at the source documents. Anyone familiar with those documents would be able to provide a more balanced view of the early work than he has articluted." -- User:Kim Meyrick 18:00, 12 Nov 2004 : I had to laugh at "I include the contributions of Baran and Davies in every presentation I make regarding the history of the Internet". If you look at every page he has linked to from his "The History of the Internet" links [http://www.lk.cs.ucla.edu/internet_history.html page], most of which he wrote, you will not find a single instance of Baran's name, and Davies is only mentioned once, as the originator of the term "packet". : I don't know which documents he is speaking of - I have read all the ones he has posted, and a great number more besides (although I don't have access to RAND's working papers, or the internal archives of DARPA). If he has more original, contemporary documents he'd like to post, I'd be happy to review them. User:Jnc User_talk:Jnc 22:41, 12 Nov 2004 (UTC) ==Date clash== Ah, the joys of people adding stuff to articles piece-meal. At ARPANET#Initial ARPANET deployment it says: : the first message ever sent over the ARPANET; it took place at 22:30PM on October 29, 1969. and then later on it says: : The first ARPANET link was established on November 21, 1969, between an IMP at UCLA and another at SRI's So how could a message have been sent on Oct 29 when the first link allegedly wasn't there until November 21? Alas, I don't have the time right now to ressarch this: can someone else straighten this out? User:Jnc User_talk:Jnc 00:41, 6 Jan 2005 (UTC)
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