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Leonard Kleinrock

Leonard Kleinrock

American engineer and computer scientist
Leonard Kleinrock
The basics

Quick Facts

Intro American engineer and computer scientist
A.K.A. Тоҷикӣ
Is Mathematician Computer scientist Inventor Professor
From United States of America
Type Academia Business Mathematics Technology Science
Gender male
Birth 13 June 1934, New York City, USA
Age: 86 years
Star sign GeminiGemini
Residence New York City, USA; Los Angeles, USA
The details


Leonard Kleinrock (born June 13, 1934) is an American computer scientist. A professor at UCLA's Henry Samueli School of Engineering and Applied Science, he made several important contributions to the field of computer science, in particular to the theoretical foundations of computer networking. He played an influential role in the development of the ARPANET, the precursor to the Internet, at UCLA.

Education and career

Kleinrock was born in New York City on June 13, 1934 to a Jewish family, 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 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.


Queueing theory

Kleinrock's best-known and significant work is on queuing theory, which has applications in many fields, initially to message switching (in the 1960s) and later as a key mathematical background to packet switching (in the 1970s). His initial contribution to this field was his doctoral thesis at the Massachusetts Institute of Technology in 1962, published in book form in 1964; he later published several of the standard works on the subject.

After Larry Roberts learned about packet switching at the 1967 Symposium on Operating Systems Principles, he asked Kleinrock to carry out the theoretical work to measure the performance of packet switching in the ARPANET, the forerunner of the Internet. Kleinrock's work underpinned the development of packet-switching networks in the 1970s.

In 2004, Kleinrock described this 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.

His theoretical work on hierarchical routing in the late 1970s with student Farouk Kamoun remains critical to the operation of the Internet today.

In 2001 he received the Draper Prize "for the development of the Internet". However, the contribution of Kleinrock's work in the early 1960s to originating the concept of packet switching is disputed, including by Robert Taylor, Paul Baran, and Donald Davies. Baran and Davies are recognized by historians and the U.S. National Inventors Hall of Fame for independently inventing the concept of digital packet switching used in modern computer networking including the Internet.


The first message on the ARPANET was sent by UCLA student programmer Charley Kline, 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 IMP at UCLA and the IMP at the Stanford Research Institute. By December 5, 1969, the entire four-node network was established.

In 1988, Kleinrock was the chairman of a group that presented the report Toward a National Research Network to the U.S. Congress. This report was highly influential and was used to develop the High Performance Computing Act of 1991, that was influential in the development of the Internet as it is known today. Funding from the bill was used in the development of the 1993 web browser Mosaic, at the National Center for Supercomputing Applications (NCSA).

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. Kleinrock claims to have committed the first illegal act on the Internet, having sent a request for return of his electric razor after a meeting in England in 1973. At the time, use of the Internet for personal reasons was unlawful.


He has received numerous professional awards. 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." In 2010 he shared the Dan David Prize. In 2012, Kleinrock was inducted into the Internet Hall of Fame by 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 Fellows of the Institute for Operations Research and the Management Sciences. In September 2014, Leonard Kleinrock was awarded the ACM SIGMOBILE Outstanding Contribution Award at MobiCom 2014.

Leonard Kleinrock has been granted with 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.


The contents of this page are sourced from Wikipedia article on 07 Mar 2020. The contents are available under the CC BY-SA 4.0 license.
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