Leonard Kleinrock
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Leonard Kleinrock (born June 13, 1934) is an American
computer scientist A computer scientist is a scientist who specializes in the academic study of computer science. Computer scientists typically work on the theoretical side of computation. Although computer scientists can also focus their work and research on ...
and Internet pioneer. He is Distinguished Professor Emeritus of Computer Science at
UCLA The University of California, Los Angeles (UCLA) is a public land-grant research university in Los Angeles, California, United States. Its academic roots were established in 1881 as a normal school then known as the southern branch of the C ...
's Henry Samueli School of Engineering and Applied Science. Kleinrock made several important contributions to the field of
computer science Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, ...
, in particular to the mathematical foundations of
data communication 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, optic ...
in
computer network A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or b ...
ing. He has received numerous prestigious awards. In the early 1960s, Kleinrock pioneered the application of
queueing theory Queueing theory is the mathematical study of waiting lines, or queues. A queueing model is constructed so that queue lengths and waiting time can be predicted. Queueing theory is generally considered a branch of operations research because th ...
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 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 tec ...
. In the 1970s, he applied queueing theory to model and measure the performance of
packet switching In telecommunications, packet switching is a method of grouping Data (computing), data into short messages in fixed format, i.e. ''network packet, packets,'' that are transmitted over a digital Telecommunications network, network. Packets consi ...
networks and published several of the standard works on the subject. He supervised graduate students who worked on the
communication protocol A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any variation of a physical quantity. The protocol defines the rules, syntax, semantics (computer science), sem ...
s for the ARPANET including students whose later work on
internetworking Internetworking is the practice of interconnecting multiple computer networks. Typically, this enables any pair of hosts in the connected networks to exchange messages irrespective of their hardware-level networking technology. The resulting sys ...
and the
Internet protocol suite The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are ...
led to the networking technology employed in the
Internet The Internet (or internet) is the Global network, global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a internetworking, network of networks ...
. His theoretical work on hierarchical routing in the late 1970s with student Farouk Kamoun remains critical to the operation of the Internet today.


Education and career

Leonard Kleinrock was born in
New York City New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...
on June 13, 1934, to a
Jewish Jews (, , ), or the Jewish people, are an ethnoreligious group and nation, originating from the Israelites of History of ancient Israel and Judah, ancient Israel and Judah. They also traditionally adhere to Judaism. Jewish ethnicity, rel ...
family, and graduated from the noted
Bronx High School of Science The Bronx High School of Science is a State school, public Specialized high schools in New York City, specialized high school in the Bronx in New York City. It is operated by the New York City Department of Education. Admission to Bronx Science ...
in 1951. He received a Bachelor of Electrical Engineering degree in 1957 from the
City College of New York The City College of the City University of New York (also known as the City College of New York, or simply City College or CCNY) is a Public university, public research university within the City University of New York (CUNY) system in New York ...
, and a master's degree and a doctorate (Ph.D.) in
electrical engineering Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems that use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the l ...
and
computer science Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, ...
from the
Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of moder ...
(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.


Achievements


Queueing theory

Kleinrock's best-known and most-significant work is on
queueing theory Queueing theory is the mathematical study of waiting lines, or queues. A queueing model is constructed so that queue lengths and waiting time can be predicted. Queueing theory is generally considered a branch of operations research because th ...
, a major topic of
applied mathematics Applied mathematics is the application of mathematics, mathematical methods by different fields such as physics, engineering, medicine, biology, finance, business, computer science, and Industrial sector, industry. Thus, applied mathematics is a ...
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 Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas pi ...
. His thesis went on to apply
probability theory Probability theory or probability calculus is the branch of mathematics concerned with probability. Although there are several different probability interpretations, probability theory treats the concept in a rigorous mathematical manner by expre ...
to model queueing delays in a generalized communication network. "Many of the theoretical studies of the performance and design of the ARPA Network were developments of earlier work by Kleinrock ... Although these works concerned message switching networks, they were the basis for a lot of the ARPA network investigations ... The intention of the work of Kleinrock n 1961was to analyse the performance of store and forward networks, using as the primary performance measure the average message delay. ... Kleinrock n 1970extended the theoretical approaches of is 1961 workto the early ARPA network."
Donald Davies Donald Watts Davies, (7 June 1924 – 28 May 2000) was a Welsh computer scientist and Internet pioneer who was employed at the UK National Physical Laboratory (NPL). During 1965-67 he invented modern data communications, including packet s ...
, in his 1966 paper on
packet switching In telecommunications, packet switching is a method of grouping Data (computing), data into short messages in fixed format, i.e. ''network packet, packets,'' that are transmitted over a digital Telecommunications network, network. Packets consi ...
, applied Kleinorck's techniques to show that "there is an ample margin between the estimated performance of the acket-switchedsystem and the stated requirement" in terms of a satisfactory response time for a human user. This addressed a key question about the viability of computer networking. pp. III-40-1


ARPANET

A contemporary from MIT, Larry Roberts, brought Leonard Kleinrock into the
ARPANET 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 tec ...
project informally in early 1967. 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." Later that year, Roberts learned about packet switching from a paper written by Davies, presented at the October 1967
Symposium on Operating Systems Principles In Ancient Greece, the symposium (, ''sympósion'', from συμπίνειν, ''sympínein'', 'to drink together') was the part of a banquet that took place after the meal, when drinking for pleasure was accompanied by music, dancing, recitals, o ...
, and incorporated the concept into the proposal for the ARPANET. Kleinrock was awarded a contract in 1968 to establish a Network Measurement Center (NMC) to measure and model the performance of the network. His mathematical work studied and influenced the development of the early ARPANET. In addition, Kleinrock managed the software team at UCLA — including Steve Crocker, Jon Postel, and
Vint Cerf Vinton Gray Cerf (; born June 23, 1943) is an American Internet pioneer and is recognized as one of "the fathers of the Internet", sharing this title with TCP/IP co-developer Robert Kahn. He has received honorary degrees and awards that inclu ...
— who developed the host-host protocol for the ARPANET, the Network Control Program (NCP). The first message on the ARPANET was sent by a UCLA undergraduate student, Charley Kline, who was supervised by Kleinrock. 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". The first permanent ARPANET link was established on November 21, 1969, between the
Interface Message Processor 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 r ...
(IMP) at UCLA and the IMP at the Stanford Research Institute. By December 5, 1969, the initial four-node network was established. Kleinrock used the ARPANET for
instant messaging Instant messaging (IM) technology is a type of synchronous computer-mediated communication involving the immediate ( real-time) transmission of messages between two or more parties over the Internet or another computer network. Originally involv ...
from the U.S. to Larry Roberts in
England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...
in 1973, employing the network for a modern every-day use.


Internet

Kleinrock published hundreds of research papers, which ultimately launched a new field of research on the theory and application of queueing theory to computer networks. In this role, he supervised the research of scores of graduate students. 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. 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 Internetworking is the practice of interconnecting multiple computer networks. Typically, this enables any pair of hosts in the connected networks to exchange messages irrespective of their hardware-level networking technology. The resulting sys ...
and the
Internet protocol suite The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are ...
led to the networking technology employed in the
Internet The Internet (or internet) is the Global network, global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a internetworking, network of networks ...
. Kleinrock's work published in the mid-1970s on the performance of the ARPANET, which was discussed at the
International Network Working Group The International Network Working Group (INWG) was a group of prominent computer science researchers in the 1970s who studied and developed Standardization, standards and communication protocol, protocols for interconnection of computer networks. Se ...
, underpinned the development of the
Transmission Control Protocol The Transmission Control Protocol (TCP) is one of the main communications protocol, protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, th ...
of the
Internet protocol suite The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are ...
. 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. Kleinrock's theoretical work on hierarchical routing with student Farouk Kamoun remains critical to the operation of the Internet today. 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". Although the U.S. did not build a nationwide
national research and education network A national research and education network (NREN) is a specialised internet service provider dedicated to supporting the needs of the research and education communities within a country. It is usually distinguished by support for a high-speed backb ...
, this report influenced
Al Gore Albert Arnold Gore Jr. (born March 31, 1948) is an American former politician, businessman, and environmentalist who served as the 45th vice president of the United States from 1993 to 2001 under President Bill Clinton. He previously served as ...
to pursue the development of the High Performance Computing Act of 1991, which helped facilitate development of the Internet as it is known today. Funding from the bill was used in the development of the 1993 web browser
Mosaic A mosaic () is a pattern or image made of small regular or irregular pieces of colored stone, glass or ceramic, held in place by plaster/Mortar (masonry), mortar, and covering a surface. Mosaics are often used as floor and wall decoration, and ...
at the
National Center for Supercomputing Applications The National Center for Supercomputing Applications (NCSA) is a unit of the University of Illinois Urbana-Champaign, and provides high-performance computing resources to researchers in the United States. NCSA is currently led by Professor Bill ...
(NCSA), which accelerated the adoption of the
World Wide Web The World Wide Web (WWW or simply the Web) is an information system that enables Content (media), content sharing over the Internet through user-friendly ways meant to appeal to users beyond Information technology, IT specialists and hobbyis ...
.


Packet switching 'paternity dispute'

In 1990, Kleinrock said:
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". By 1997, he claimed priority on the invention of packet switching and to have convinced Larry Roberts to adopt the technique. 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, including Robert Taylor,
Paul Baran Paul Baran (born Pesach Baran ; April 29, 1926 – March 26, 2011) was a Polish-American 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 do ...
, and
Donald Davies Donald Watts Davies, (7 June 1924 – 28 May 2000) was a Welsh computer scientist and Internet pioneer who was employed at the UK National Physical Laboratory (NPL). During 1965-67 he invented modern data communications, including packet s ...
. Historians and the U.S.
National Inventors Hall of Fame The National Inventors Hall of Fame (NIHF) is an American not-for-profit organization, founded in 1973, which recognizes individual engineers and inventors who hold a US patent of significant technology. Besides the Hall of Fame, it also operate ...
recognize Baran and Davies for independently inventing the concept of digital packet switching used in modern computer networking including the Internet.


Awards and recognition

Kleinrock made several important contributions to the field of computer science, in particular to the mathematical foundations of
data communication 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, optic ...
in
computer network A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or b ...
ing. He has received numerous professional awards. In 1980, he was elected a member of the
National Academy of Engineering The National Academy of Engineering (NAE) is an American Nonprofit organization, nonprofit, NGO, non-governmental organization. It is part of the National Academies of Sciences, Engineering, and Medicine (NASEM), along with the National Academ ...
for pioneering contributions to the field and leadership as an educator in computer communications networks. In 2001 he received the Draper Prize "for the development of the Internet". Kleinrock was selected to receive the prestigious
National Medal of Science The National Medal of Science is an honor bestowed by the President of the United States to individuals in science and engineering who have made important contributions to the advancement of knowledge in the fields of behavioral science, behavior ...
, 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." In 2010 he shared the Dan David Prize. 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. He was elected as a member into the
National Academy of Engineering The National Academy of Engineering (NAE) is an American Nonprofit organization, nonprofit, NGO, non-governmental organization. It is part of the National Academies of Sciences, Engineering, and Medicine (NASEM), along with the National Academ ...
. In 2012, Kleinrock was inducted into the
Internet Hall of Fame The Internet Hall of Fame is an honorary lifetime achievement award administered by the Internet Society (ISOC) in recognition of individuals who have made significant contributions to the development and advancement of the Internet. Overview ...
by the
Internet Society The Internet Society (ISOC) is an American non-profit advocacy organization founded in 1992 with local chapters around the world. It has offices in Reston, Virginia, United States, and Geneva, Switzerland. Organization The Internet Society ...
. 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
Fellow A fellow is a title and form of address for distinguished, learned, or skilled individuals in academia, medicine, research, and industry. The exact meaning of the term differs in each field. In learned society, learned or professional society, p ...
s of the
Institute for Operations Research and the Management Sciences The Institute for Operations Research and the Management Sciences (INFORMS) is an international society for practitioners in the fields of operations research Operations research () (U.S. Air Force Specialty Code: Operations Analysis), often s ...
. 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. 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.Silvester, John, and Parviz Kermani. “Professor Leonard Kleinrock – Tribute Volume.” ''Computer networks'' (Amsterdam, Netherlands : 1999) 66 (2014): 1–3.


See also

*
History of the Internet The history of the Internet originated in the efforts of scientists and engineers to build and interconnect computer networks. The Internet protocol suite, Internet Protocol Suite, the set of rules used to communicate between networks and devi ...
* Internet pioneers * '' Nerds 2.0.1'' – 1998 documentary in which Kleinrock gives a lengthy interview * Protocol Wars


Works

* * * * * * * * *


References


External links

* *
Biography of Leonard Kleinrock
from the Institute for Operations Research and the Management Sciences * * * * Kleinrock discusses his work on the ARPANET; his dissertation work in queueing theory; and his move to the University of California at Los Angeles (UCLA). As one of the main contractors for the ARPANET, Kleinrock describes his involvement in discussions before the official DARPA request was issued, the people involved in the ARPANET work at UCLA, the installation of the first node of the network, the Network Measurement Center, and his relationships with Lawrence Roberts and the IPT Office,
Bolt, Beranek and Newman Raytheon BBN (originally Bolt, Beranek and Newman, Inc.) is an American research and development company based in Cambridge, Massachusetts. In 1966, the Franklin Institute awarded the firm the Frank P. Brown Medal, in 1999 BBN received the ...
, and the Network Analysis Corporation. * Video: * Video: * Video: * Video: {{DEFAULTSORT:Kleinrock, Leonard 1934 births American computer scientists The Bronx High School of Science alumni City College of New York alumni 2000 fellows of the Association for Computing Machinery Internet pioneers Living people MIT School of Engineering alumni Queueing theorists University of California, Los Angeles faculty Jewish American scientists Draper Prize winners Fellows of the Institute for Operations Research and the Management Sciences Members of the United States National Academy of Engineering 20th-century American scientists 21st-century American scientists Scientists from New York City