Leonard Kleinrock | |
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Born | New York City, U.S. | June 13, 1934
Nationality | American |
Alma mater | City College of New York Massachusetts Institute of Technology |
Known for | Queueing theory, ARPANET, Internet development |
Awards |
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Scientific career | |
Fields | |
Institutions | University of California, Los Angeles |
Thesis | |
Doctoral advisor | Edward Arthurs [2] Claude Shannon |
Doctoral students | Chris Ferguson |
Leonard Kleinrock (born June 13, 1934) is an American computer scientist and Internet pioneer. He is Distinguished Professor Emeritus of Computer Science at UCLA's Henry Samueli School of Engineering and Applied Science. Kleinrock made several important contributions to the field of computer science, in particular to the mathematical foundations of data communication in computer networking. He has received numerous prestigious awards.
In the early 1960s, Kleinrock pioneered the application of queueing theory to model delays in message switching networks in his Ph.D. thesis, published as a book in 1964. In the late 1960s and 1970s, he played an influential role in the development of the ARPANET. In the 1970s, he applied queueing theory to model and measure the performance of packet switching networks and published several of the standard works on the subject. He supervised graduate students who worked on the communication protocols for the ARPANET including students whose later work on internetworking and the Internet protocol suite led to the networking technology employed in the Internet. His theoretical work on hierarchical routing in the late 1970s with student Farouk Kamoun remains critical to the operation of the Internet today.
Leonard Kleinrock was born in New York City on June 13, 1934, to a Jewish family, [3] and graduated from the noted Bronx High School of Science in 1951. He received a Bachelor of Electrical Engineering degree in 1957 from the City College of New York, and a master's degree and a doctorate (Ph.D.) in electrical engineering and computer science from the Massachusetts Institute of Technology (MIT) in 1959 and 1963 respectively. He then joined the faculty at the University of California at Los Angeles (UCLA), where he remains to the present day; during 1991–1995 he served as the chairman of the Computer Science Department there. [4]
Kleinrock's best-known and most-significant work is on queueing theory, a major topic of applied mathematics that has applications in many fields. His thesis proposal in 1961, Information Flow in Large Communication Nets, led to a doctoral thesis at MIT in 1962, Message Delay in Communication Nets with Storage, later published as book in 1964, Communication Nets: Stochastic Message Flow and Delay. In this work, he researched the configuration and operation of communication networks, considering design parameters such as "channel capacity, effect of priority discipline, choice of routing procedure, and design of topological structure". He analyzed delays in Plan 55-A, a message switching system operated by Western Union for processing telegrams. His thesis went on to apply probability theory to model queueing delays in a generalized communication network. [5] [6]
Donald Davies, in his 1966 paper on packet switching, applied Kleinorck's techniques to show that "there is an ample margin between the estimated performance of the [packet-switched] system and the stated requirement" in terms of a satisfactory response time for a human user. [7] This addressed a key question about the viability of computer networking. [8]
A contemporary from MIT, Larry Roberts, brought Leonard Kleinrock into the ARPANET project informally in early 1967. [9] Roberts asked Frank Westervelt to explore the questions of message size and contents for the network, and to write a position paper on the intercomputer communication protocol including “conventions for character and block transmission, error checking and retransmission, and computer and user identification." [10] Later that year, Roberts learned about packet switching from a paper written by Davies, presented at the October 1967 Symposium on Operating Systems Principles, and incorporated the concept into the proposal for the ARPANET. [11] [12] [13] [14]
Kleinrock was awarded a contract in 1968 to establish a Network Measurement Center (NMC) to measure and model the performance of the network. [15] His mathematical work studied and influenced the development of the early ARPANET. [5] [16] [17] [18] In addition, Kleinrock managed the software team at UCLA — including Steve Crocker, Jon Postel, and Vint Cerf — who developed the host-host protocol for the ARPANET, the Network Control Program (NCP). [19]
The first message on the ARPANET was sent by a UCLA undergraduate student, [20] Charley Kline, who was supervised by Kleinrock. [21] [22] At 10:30 p.m, on October 29, 1969, from Boelter Hall 3420, the school's main engineering building, Kline transmitted from the university's SDS Sigma 7 host computer to the Stanford Research Institute's SDS 940 host computer. The message text was the word "login"; the "l" and the "o" letters were transmitted, but the system then crashed. Hence, the literal first message over the ARPANET was "lo". About an hour later, having recovered from the crash, the SDS Sigma 7 computer effected a full "login". [20] [23] The first permanent ARPANET link was established on November 21, 1969, between the Interface Message Processor (IMP) at UCLA and the IMP at the Stanford Research Institute. By December 5, 1969, the initial four-node network was established. [24] [25]
Kleinrock used the ARPANET for instant messaging from the U.S. to Larry Roberts in England in 1973, employing the network for a modern every-day use. [26] [27]
Kleinrock published hundreds of research papers, [28] [29] which ultimately launched a new field of research on the theory and application of queueing theory to computer networks. [5] [30] [31] [32] In this role, he supervised the research of scores of graduate students. [29] [33] He disseminated his research and that of his students to wider audiences for academic and commercial use, and organized hundreds of commercial seminars presented by experts and pioneers in the U.S. and internationally. [33] [29] Many graduate students that Kleinrock supported based their careers on expertise they acquired while working on the ARPANET with him, including several whose later work on internetworking and the Internet protocol suite led to the networking technology employed in the Internet. [8] [30] Kleinrock's work published in the mid-1970s on the performance of the ARPANET, which was discussed at the International Network Working Group, [34] underpinned the development of the Transmission Control Protocol of the Internet protocol suite. [35] [36] [37] His analytic work in the 1970s addressed packet switching networks, packet radio networks, local area networks, broadband networks, nomadic computing, peer-to-peer networks, and intelligent software agents. [28] Kleinrock's theoretical work on hierarchical routing with student Farouk Kamoun remains critical to the operation of the Internet today. [38] [39]
In 1988, Kleinrock was the chairman of a group that presented the report Toward a National Research Network to the U.S. Congress, concluding that "There is a clear and urgent need for a national research network". [40] Although the U.S. did not build a nationwide national research and education network, this report influenced Al Gore to pursue the development of the High Performance Computing Act of 1991, [41] which helped facilitate development of the Internet as it is known today. [42] Funding from the bill was used in the development of the 1993 web browser Mosaic at the National Center for Supercomputing Applications (NCSA), which accelerated the adoption of the World Wide Web. [43] [44]
In 1990, Kleinrock said: [33]
The thing that really drove my own research was the idea of a message switching network, which was a precursor to the packet switching networks. The mathematical tool that had been developed in queueing theory, namely queueing networks, matched perfectly the model of computer networks. Actually, it didn't match perfectly and I had to adjust that model to fit the realities of computer networks. Then I developed some design procedures as well for optimal capacity assignment, routing procedures and topology design.
Beginning in the mid-1990s, Kleinrock sought to be recognized "as the father of modern data networking". [45] By 1997, he claimed priority on the invention of packet switching and to have convinced Larry Roberts to adopt the technique. [46] In 2004, he described his work as:
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.
However, Kleinrock's claims that his work in the early 1960s originated the concept of packet switching and that his work was a source of the packet switching concepts used in the ARPANET are disputed by other Internet pioneers, [45] [47] [48] [49] including Robert Taylor, [50] Paul Baran, [51] and Donald Davies. [52] Historians and the U.S. National Inventors Hall of Fame recognize Baran and Davies for independently inventing the concept of digital packet switching used in modern computer networking including the Internet. [11] [12] [53] [54] [55]
Kleinrock made several important contributions to the field of computer science, in particular to the mathematical foundations of data communication in computer networking. He has received numerous professional awards. In 1980, he was elected a member of the National Academy of Engineering for pioneering contributions to the field and leadership as an educator in computer communications networks. [56] In 2001 he received the Draper Prize "for the development of the Internet". [57] Kleinrock was selected to receive the prestigious National Medal of Science, the nation's highest scientific honor, from President George W. Bush in the White House on September 29, 2008. "The 2007 National Medal of Science to Leonard Kleinrock for his fundamental contributions to the mathematical theory of modern data networks, and for the functional specification of packet switching, which is the foundation of Internet technology. His mentoring of generations of students has led to the commercialization of technologies that have transformed the world." [1]
In 2010 he shared the Dan David Prize. [58] UCLA Room 3420 at Boelter Hall was restored to its condition of 1969 and converted into the Kleinrock Internet Heritage Site and Archive. It opened to the public with a grand opening attended by Internet pioneers on October 29, 2011. [23] [59]
He was elected as a member into the National Academy of Engineering. In 2012, Kleinrock was inducted into the Internet Hall of Fame by the Internet Society. [28] Leonard Kleinrock was inducted into IEEE-Eta Kappa Nu (IEEE-ΗΚΝ) in 2011 as an Eminent Member. The designation of Eminent Member is the organization's highest membership grade and is conferred upon those select few whose outstanding technical attainments and contributions through leadership in the fields of electrical and computer engineering have significantly benefited society. He was elected to the 2002 class of Fellows of the Institute for Operations Research and the Management Sciences. [60] In September 2014, Leonard Kleinrock was awarded the ACM SIGMOBILE Outstanding Contribution Award at MobiCom 2014.
Leonard Kleinrock was given the 2014 BBVA Foundation Frontiers of Knowledge Award "for his seminal contributions to the theory and practical development of the Internet," in the words of the jury's citation. [61]
In 2014, a special edition of Computer Networks was published in his honor. Articles were written in recognition of Kleinrock's contributions to queueing theory, packet switching, computer communication networks and the development of the Internet and related network technologies. [62]
The history of the Internet has its origin 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.
A datagram is a basic transfer unit associated with a packet-switched network. Datagrams are typically structured in header and payload sections. Datagrams provide a connectionless communication service across a packet-switched network. The delivery, arrival time, and order of arrival of datagrams need not be guaranteed by the network.
Data communication, including data transmission and data reception, is the transfer of data, transmitted and received over a point-to-point or point-to-multipoint communication channel. Examples of such channels are copper wires, optical fibers, wireless communication using radio spectrum, storage media and computer buses. The data are represented as an electromagnetic signal, such as an electrical voltage, radiowave, microwave, or infrared signal.
In telecommunications, packet switching is a method of grouping data into short messages in fixed format, i.e. packets, that are transmitted over a digital network. Packets are made of a header and a payload. Data in the header is used by networking hardware to direct the packet to its destination, where the payload is extracted and used by an operating system, application software, or higher layer protocols. Packet switching is the primary basis for data communications in computer networks worldwide.
In telecommunications, message switching involves messages routed in their entirety, one hop at a time. It evolved from circuit switching and was the precursor of packet switching.
The end-to-end principle is a design framework in computer networking. In networks designed according to this principle, guaranteeing certain application-specific features, such as reliability and security, requires that they reside in the communicating end nodes of the network. Intermediary nodes, such as gateways and routers, that exist to establish the network, may implement these to improve efficiency but cannot guarantee end-to-end correctness.
The Advanced Research Projects Agency Network (ARPANET) was the first wide-area packet-switched network with distributed control and one of the first computer networks to implement the TCP/IP protocol suite. Both technologies became the technical foundation of the Internet. The ARPANET was established by the Advanced Research Projects Agency of the United States Department of Defense.
Bob Kahn is an American electrical engineer who, along with Vint Cerf, first proposed the Transmission Control Protocol (TCP) and the Internet Protocol (IP), the fundamental communication protocols at the heart of the Internet.
Donald Watts Davies, was a Welsh computer scientist and Internet pioneer who was employed at the UK National Physical Laboratory (NPL).
Paul Baran was an American-Jewish engineer who was a pioneer in the development of computer networks. He was one of the two independent inventors of packet switching, which is today the dominant basis for data communications in computer networks worldwide, and went on to start several companies and develop other technologies that are an essential part of modern digital communication.
The Interface Message Processor (IMP) was the packet switching node used to interconnect participant networks to the ARPANET from the late 1960s to 1989. It was the first generation of gateways, which are known today as routers. An IMP was a ruggedized Honeywell DDP-516 minicomputer with special-purpose interfaces and software. In later years the IMPs were made from the non-ruggedized Honeywell 316 which could handle two-thirds of the communication traffic at approximately one-half the cost. An IMP requires the connection to a host computer via a special bit-serial interface, defined in BBN Report 1822. The IMP software and the ARPA network communications protocol running on the IMPs was discussed in RFC 1, the first of a series of standardization documents published by what later became the Internet Engineering Task Force (IETF).
Simon S. Lam is an American computer scientist and Internet pioneer. He retired in 2018 from The University of Texas at Austin as Professor Emeritus and Regents' Chair Emeritus in Computer Science #1. He made seminal and important contributions to transport layer security, packet network verification, as well as network protocol design, verification, and performance analysis.
Larry Roberts was an American computer scientist and Internet pioneer.
A computer network is a set of computers sharing resources located on or provided by network nodes. Computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are made up of telecommunication network technologies based on physically wired, optical, and wireless radio-frequency methods that may be arranged in a variety of network topologies.
Farouk Kamoun is a Tunisian computer scientist and professor of computer science at the National School of Computer Sciences (ENSI) of Manouba University, Tunisia. He contributed in the late 1970s to significant research in the field of computer networking in relation with the first ARPANET network. He is also one of the pioneers of the development of the Internet in Tunisia in the early 1990s.
IEEE Internet Award is a Technical Field Award established by the IEEE in June 1999. The award is sponsored by Nokia Corporation. It may be presented annually to an individual or up to three recipients, for exceptional contributions to the advancement of Internet technology for network architecture, mobility and/or end-use applications. Awardees receive a bronze medal, certificate, and honorarium.
The NPL network, or NPL Data Communications Network, was a local area computer network operated by a team from the National Physical Laboratory (NPL) in London that pioneered the concept of packet switching.
Roger Anthony Scantlebury is a British computer scientist and Internet pioneer who worked at the National Physical Laboratory (NPL) and later at Logica.
The Protocol Wars were a long-running debate in computer science that occurred from the 1970s to the 1990s, when engineers, organizations and nations became polarized over the issue of which communication protocol would result in the best and most robust networks. This culminated in the Internet–OSI Standards War in the 1980s and early 1990s, which was ultimately "won" by the Internet protocol suite (TCP/IP) by the mid-1990s when it became the dominant protocol suite through rapid adoption of the Internet.
W. Clark's message switching proposal (appended to Taylor's letter of April 24, 1967, to Engelbart )were reviewed.
Historians credit seminal insights to Welsh scientist Donald W. Davies and American engineer Paul Baran
Roger Scantlebury ... from Donald Davies' team ... presented a detailed design study for a packet switched network. It was the first Roberts had heard of it. ... Roberts also learned from Scantlebury, for the first time, of the work that had been done by Paul Baran at RAND a few years earlier.
On Kleinrock's influence, see Frank, Kahn, and Kleinrock 1972, p. 265; Tanenbaum 1989, p. 631.
The third paper by Kleinrock [5] derives procedures for optimizing the capacity of the transmission facility in order to minimize cost and average message delay. ... [5] L KLEINROCK. Analytic and simulation methods in Computer Network Design AFIPS Conference Proceedings, May 1970
7. H. Frank, R. E. Kahn and L. Kleinrock, "Computer communication network design—experience with theory and practice", AFIPS Spring Joint Comput. Conf., pp. 255-270, 1972.
In mathematical modelling use is made of the theories of queueing processes and of flows in networks, describing the performance of the network in a set of equations. ... The analytic method has been used with success by Kleinrock and others, but only if important simplifying assumptions are made. ... It is heartening in Kleinrock's work to see the good correspondence achieved between the results of analytic methods and those of simulation.
Hierarchical addressing systems for network routing have been proposed by Fultz and, in greater detail, by McQuillan. A recent very full analysis may be found in Kleinrock and Kamoun.
The hierarchical approach is further motivated by theoretical results (e.g., [16]) which show that, by optimally placing separators, i.e., elements that connect levels in the hierarchy, tremendous gain can be achieved in terms of both routing table size and update message churn. ... [16] KLEINROCK, L., AND KAMOUN, F. Hierarchical routing for large networks: Performance evaluation and optimization. Computer Networks (1977).
This led to an outcry among many of the other Internet pioneers, who publicly attacked Kleinrock and said that his brief mention of breaking messages into smaller pieces did not come close to being a proposal for packet switching ... until the mid-1990s, Kleinrock had credited [Baran and Davies] with coming up with the idea of packet switching
Leonard Kleinrock and Lawrence (Larry) Roberts, neither of whom were directly involved in the invention of packet switching ... Dr Willis H. Ware, Senior Computer Scientist and Research at the RAND Corporation, notes that Davies (and others) were troubled by what they regarded as in appropriate claims on the invention of packet switching
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: CS1 maint: multiple names: authors list (link)Authors who have interviewed dozens of Arpanet pioneers know very well that the Kleinrock-Roberts claims are not believed.
The Internet is really the work of a thousand people," Mr. Baran said. "And of all the stories about what different people have done, all the pieces fit together. It's just this one little case that seems to be an aberration.
I can find no evidence that he understood the principles of packet switching.[ dead link ]
The NPL group influenced a number of American computer scientists in favor of the new technique, and they adopted Davies's term "packet switching" to refer to this type of network. Roberts also adopted some specific aspects of the NPL design.
Paul Baran, an engineer celebrated as the co-inventor (along with Donald Davies) of the packet switching technology that is the foundation of digital networks