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Leonard Kleinrock


Leonard Kleinrock

Leonard Kleinrock
Born (1934-06-13) June 13, 1934
New York City
Residence Los Angeles
Nationality United States
Fields Engineering
Computer science
Institutions UCLA
Alma mater City College of New York, MIT
Doctoral advisor Edward Arthurs[1]
Doctoral students Chris Ferguson
Known for Internet development
Notable awards Marconi Prize (1986)
Harry H. Goode Memorial Award (1996)
National Medal of Science[2] (2007)
IEEE Alexander Graham Bell Medal (2012)
BBVA Foundation Frontiers of Knowledge Award (2014)

Leonard Kleinrock (born June 13, 1934) is an American engineer and computer scientist. A computer science professor at UCLA's Henry Samueli School of Engineering and Applied Science, he made several important contributions to the field of computer networking, 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.[3]

His most well-known and significant work is his early work on queueing theory, which has applications in many fields, among them as a key mathematical background to packet switching, one of the basic technologies of the Internet. 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. He described this work as:

"Basically, what I did for my PhD research in 1961–1962 was to establish a mathematical theory of packet networks..."

His theoretical work on hierarchical routing in the late 1970s with student Farouk Kamoun, is now critical to the operation of today's worldwide Internet.


  • Education and career 1
    • ARPANET and the Internet 1.1
  • Awards 2
  • See also 3
  • Works 4
  • References 5
  • External links 6

Education and career

Kleinrock was born in New York City on June 13, 1934 to a Jewish family,[4] 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.[5]

ARPANET and 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 building.[6] Supervised by Kleinrock, 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.[7]

In 1988, Kleinrock was the chairman of a group that presented the report Toward a National Research Network to the U.S. Congress.[8] This report was highly influential and was used to develop the High Performance Computing Act of 1991,[9] that was influential in the development of the Internet as it is known today.[10] Funding from the bill was used in the development of the 1993 web browser Mosaic, at the National Center for Supercomputing Applications (NCSA).[11]

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.[6][12] 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.[13]


2012 Internet Hall of Fame inductees, including Leonard Kleinrock (seated, fifth from the left)

He has received numerous professional awards. Kleinrock was selected to receive the prestigious 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.

See also


  • Kleinrock, Leonard (May 1961). "Information Flow in Large Communication Nets". Ph.D. Thesis Proposal ( 
  • Kleinrock, Leonard (July 1961). "Information Flow in Large Communication Nets". RLE Quarterly Progress Report ( 
  • Kleinrock, Leonard (April 1962). "Information Flow in Large Communication Nets". RLE Quarterly Progress Report ( 
  • Kleinrock, Leonard (December 1962). "Message Delay in Communication Nets with Storage" (PDF). (PhD thesis) (Cambridge, MA:  
  • Kleinrock, Leonard (1964). Communication Nets: Stochastic Message Flow and Design. McGraw-Hill. p. 220.  
  • Kleinrock, Leonard (2 January 1975). Queueing Systems: Volume I – Theory. New York: Wiley Interscience. p. 417.  
  • Kleinrock, Leonard (22 April 1976). Queueing Systems: Volume II – Computer Applications. New York: Wiley Interscience. p. 576.  
  • Kleinrock, Leonard; Kamoun, Farok (January 1977). "Hierarchical Routing for Large Networks, Performance Evaluation and Optimization". Computer Networks 1 (3): 155–174. 
  • Kleinrock, Leonard; Gail, Richard (12 April 1996). Queueing Systems: Problems and Solutions. Wiley-Interscience. p. 240.  


  1. ^ Leonard Kleinrock at the Mathematics Genealogy Project
  2. ^ a b "Eight National Medals of Science Awardees Honored at Gala".  
  3. ^ Rosenbaum, Philip (29 October 2009). "'"Web pioneer recalls 'birth of the Internet. CNN. Retrieved October 30, 2009. 
  4. ^ "Jews in Computer & Information Science". The Jewish Contribution to World Civilization web site. Retrieved 5 July 2011. 
  5. ^ "Leonard Kleinrock's Profile".  
  6. ^ a b Savio, Jessica (1 April 2011). "Browsing history: A heritage site is being set up in Boelter Hall 3420, the room the first Internet message originated in".  
  7. ^ Sutton, Chris. "Internet Began 35 Years Ago at UCLA with First Message Ever Sent Between Two Computers".  
  8. ^ "Toward a National Research Network". 
  9. ^ "High-Performance Computing Act of 1991". Retrieved 21 March 2011. 
  10. ^ "A Bill of Rights for the Internet: What Should it Have Been at the Outset" (PDF). Retrieved 21 March 2011. 
  11. ^ Tuutti, Camille (23 September 2011). "R&D in IT essential to help US stay competitive". Federal Computer Week. Retrieved 25 May 2012. 
  12. ^ McCarty, Meghan (19 July 2011). "Beginning of the Internet commemorated in new UCLA museum".  
  13. ^ Still, tapping into the ARPANET to fetch a shaver across international lines was a bit like being a stowaway on an aircraft carrier. The ARPANET was an official federal research facility, after all, and not something to be toyed with. Kleinrock had the feeling that the stunt he’d pulled was slightly out of bounds. 'It was a thrill. I felt I was stretching the Net'. - "Where Wizards Stay Up Late: The Origins of the Internet", Chapter 7.
  14. ^ Wileen Wong Kromhout (March 15, 2010). "UCLA Internet pioneer Leonard Kleinrock looks toward future, helps students do the same". UCLA Engineering. Retrieved March 30, 2011. 
  15. ^ "2012 Inductees".  

External links

  • "Leonard Kleinrock's Home Page".  
  • "KIHC: The Kleinrock Internet History Center at UCLA".  
  • "Bibliography".  
  • "Network history links". Retrieved 11 November 2004. 
  • "Oral history interview with Leonard Kleinrock". University of Minnesota, Minneapolis: Kleinrock discusses his work on the ARPANET.  

Kleinrock discusses his dissertation work in queuing 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, and the Network Analysis Corporation.

  • "Oral history interview with Howard Frank". University of Minnesota, Minneapolis: Frank describes his work on the ARPANET, including his interaction with Roberts and the IPT Office.  
  • Video:Interview with Leonard Kleinrock.  
  • Video:Leonard Kleinrock on the first Internet connection. Retrieved 25 August 2008. 
  • Video:Leonard Kleinrock displays Internet's first router. Retrieved 25 August 2008. 
  • Video:Leonard Kleinrock on packet-switching, early Internet. Retrieved 25 August 2008. 

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