Leonard Kleinrock was born on June 13, 1934. He is an American computer scientist and an early leader in the development of the Internet. He is a Distinguished Professor Emeritus of Computer Science at UCLA's Henry Samueli School of Engineering and Applied Science. Kleinrock made important contributions to computer science, especially in the area of mathematical principles used for data communication in computer networks. He has received many respected awards for his work.

In the early 1960s, Kleinrock was one of the first to use queueing theory to study delays in message switching networks. He wrote a book about this research in 1964. In the late 1960s and 1970s, he helped develop the ARPANET, an early version of the Internet. During the 1970s, he used queueing theory to analyze and measure the performance of packet switching networks. He wrote several key books on this topic. Kleinrock also helped guide graduate students who worked on communication protocols for the ARPANET. Some of these students later contributed to the development of internetworking and the Internet protocol suite, which are used in today's Internet. In the late 1970s, Kleinrock and his student Farouk Kamoun studied hierarchical routing, a method still important for how the Internet operates today.

Education and career

Leonard Kleinrock was born in New York City on June 13, 1934, to a Jewish family. He graduated from the well-known Bronx High School of Science in 1951. In 1957, he earned a Bachelor of Electrical Engineering degree from City College in New York. He later received a master's degree in electrical engineering and computer science from the Massachusetts Institute of Technology (MIT) in 1959. He also earned his doctorate (Ph.D.) in the same fields from MIT in 1963. After completing his studies, he became a professor at the University of California, Los Angeles (UCLA) and has worked there ever since. From 1991 to 1995, he was the head of the Computer Science Department at UCLA.

Achievements

Leonard Kleinrock is best known for his work on queueing theory, a branch of applied mathematics that helps solve problems in many fields. In 1961, he proposed a thesis titled Information Flow in Large Communication Nets, which led to his doctoral thesis in 1962, Message Delay in Communication Nets with Storage. This work was later published in 1964 as Communication Nets: Stochastic Message Flow and Delay. In this research, Kleinrock studied how communication networks are designed and operate, focusing on factors like channel capacity, priority rules, routing methods, and network structure. He analyzed delays in Plan 55-A, a telegram system operated by Western Union. He also used probability theory to model delays in communication networks.

In 1966, Donald Davies used Kleinrock’s techniques in a paper on packet switching to show that a packet-switched system could meet human user requirements for response time. This helped prove that computer networking was practical.

In 1967, Larry Roberts, a colleague from MIT, invited Kleinrock to join the ARPANET project. Roberts asked Frank Westervelt to study message size and communication protocols, including rules for sending data, checking for errors, and identifying users and computers. Later that year, Roberts learned about packet switching from Davies’s paper and included the idea in the ARPANET proposal.

In 1968, Kleinrock was hired to create a Network Measurement Center (NMC) to study and improve ARPANET performance. His mathematical research influenced early ARPANET development. He also led a team at UCLA, including Steve Crocker, Jon Postel, and Vint Cerf, who designed the host-host protocol for ARPANET, called the Network Control Program (NCP).

The first message on ARPANET was sent on October 29, 1969, by a UCLA student named Charley Kline, who was guided by Kleinrock. Kline sent the word "login" from UCLA’s SDS Sigma 7 computer to Stanford Research Institute’s SDS 940 computer. Only the letters "lo" were transmitted before the system crashed. An hour later, the system recovered, and a full "login" was successfully sent. The first permanent ARPANET link was established on November 21, 1969, between UCLA and Stanford Research Institute. By December 5, 1969, the first four-node network was completed.

In 1973, Kleinrock used ARPANET to send an instant message from the U.S. to Larry Roberts in England, demonstrating a modern use of the network.

Kleinrock co-founded Linkabit and was the founder and chairman of Nomadix and the Technology Transfer Institute. He published hundreds of research papers, creating a new field of study on applying queueing theory to computer networks. He supervised many graduate students and shared their research with others through seminars and academic work. Many of his students later worked on internetworking and the Internet protocol suite. His research from the 1970s on ARPANET performance, discussed at the International Network Working Group, helped develop the Transmission Control Protocol (TCP) used in the Internet. His work also covered packet switching, local area networks, and other technologies. His theoretical work on hierarchical routing with student Farouk Kamoun remains important for the Internet today.

In 1988, Kleinrock chaired a committee that released a report to the U.S. Congress titled Toward a National Research Network, arguing that the country needed a national research network. Although the U.S. did not build one, the report influenced Al Gore to support the High Performance Computing Act of 1991, which helped develop the modern Internet. Funding from the act supported the creation of the Mosaic web browser in 1993, which helped popularize the World Wide Web. Kleinrock later led the committee that produced the 1994 report Realizing the Information Future; The Internet and Beyond.

In 1990, Kleinrock said:

Beginning in the mid-1990s, Kleinrock claimed to be the "father of modern data networking." By 1997, he stated he had convinced Larry Roberts to use packet switching. In 2004, he described his work as:

However, some Internet pioneers, including Robert Taylor, Paul Baran, and Donald Davies, disagree with Kleinrock’s claims that he originated the concept of packet switching or that his work influenced ARPANET. Historians and the U.S. National Inventors Hall of Fame recognize Baran and Davies as the independent inventors of digital packet switching used in modern computer networks, including the Internet.

Awards and recognition

Leonard Kleinrock made many important contributions to the field of computer science, especially in the basic math principles that help computers share information over networks. He has received many professional awards. In 1980, he was chosen as a member of the National Academy of Engineering for his early work in the field and for leading students in computer communication networks. In 2001, he received the Draper Prize for helping develop the Internet. In 2002, he was added to the list of Fellows for the Institute for Operations Research and the Management Sciences. Kleinrock was chosen to receive the National Medal of Science, the highest scientific honor in the country, from President George W. Bush in the White House on September 29, 2008. The 2007 National Medal of Science was given to Leonard Kleinrock for his work in the math theory of modern data networks and for creating the rules for packet switching, which is the basis of Internet technology. His teaching helped many students develop technologies that changed the world.

In 2010, he shared the Dan David Prize. A room at UCLA, Room 3420 in Boelter Hall, was restored to look like it did in 1969 and turned into the Kleinrock Internet Heritage Site and Archive. It opened to the public on October 29, 2011, with a ceremony attended by early Internet pioneers. In 2011, Kleinrock was added to the list of Eminent Members of IEEE- Eta Kappa Nu (IEEE-ΗΚΝ), which is the highest membership level in the group. This honor is given to people with major achievements in electrical and computer engineering that helped society. In 2012, Kleinrock was added to the Internet Hall of Fame by the Internet Society. In September 2014, he received the ACM SIGMOBILE Outstanding Contribution Award at MobiCom 2014. In 2014, he was given the BBVA Foundation Frontiers of Knowledge Award for his important work in the theory and practical development of the Internet, as stated by the award judges. That same year, a special edition of the journal Computer Networks was published in his honor. Articles in the journal recognized Kleinrock's work in queueing theory, packet switching, computer communication networks, and the creation of the Internet and related network technologies.

Works

• 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)." Ph.D. Thesis. Archived from the original (PDF) on March 26, 2009.
• Kleinrock, Leonard (1964). Communication Nets: Stochastic Message Flow and Design. McGraw-Hill. p. 220. ISBN 978-0486611051.
• Kleinrock, Leonard (January 2, 1975). Queueing Systems: Volume I – Theory. New York: Wiley Interscience. pp. 417. ISBN 978-0471491101.
• Kleinrock, Leonard (April 22, 1976). Queueing Systems: Volume II – Computer Applications. New York: Wiley Interscience. pp. 576. ISBN 978-0471491118.
• Kleinrock, Leonard; Kamoun, Farok (January 1977). "Hierarchical Routing for Large Networks, Performance Evaluation and Optimization." Computer Networks. 1 (3): 155–174. doi: 10.1016/0376-5075(77)90002-2.
• Kleinrock, Leonard; Gail, Richard (April 12, 1996). Queueing Systems: Problems and Solutions. Wiley-Interscience. p. 240. ISBN 978-0471555681.