Leonard Kleinrock

Leonard Kleinrock
Leonard Kleinrock
Harlem, New York City, NY
Associated organizations
University of California, MIT
Fields of study
IEEE Alexander Graham Bell Medal


Leonard Kleinrock is considered one of the fathers of the Internet for his development of packet-switching networks, providing the theory upon which the Internet exists today. Dr. Kleinrock developed the mathematical theory of packet-switching networks during the early 1960s as a graduate student at the Massachusetts Institute of Technology to handle the burst-like nature of computer data transmission and its resulting inefficiencies. Packet switching involves packaging data into specially formatted units, or packets, that identify the sender and the intended recipient and enables shared use through routing and queuing of the data. Dr. Kleinrock transferred his theory to practical deployment at the University of California, Los Angeles (UCLA) through the U.S. Defense Advanced Research Project Agency’s (DARPA) predecessor of the Internet, known as ARPANET. His host computer became the very first node of ARPANET in September 1969, and he supervised the transmission of the first message ever sent over the Internet in October 1969. His group evaluated ARPANET as it grew during the 1970s, and he proved that packet-switched networks could provide highly efficient data communications and would not fail in a full-scale deployment. This was instrumental in persuading the U.S. Government to fund Internet development. During the 1970s, Dr. Kleinrock’s pioneering work on packet radio methods provided the foundation for today’s wireless cellular communications, WiFi, and 3G/4G mobile computing technologies. Today’s emerging “cloud computing” platforms, where services are provided on-demand much like traditional utilities, were predicted by Dr. Kleinrock back in 1969.

Dr. Kleinrock is an IEEE Life Fellow. In 2012 he received the IEEE Alexander Graham Bell Medal “For pioneering contributions to modeling, analysis, and design of packet-switching networks.” He is currently a Distinguished Professor of Computer Science at UCLA, where has worked since 1963.

Further Reading

Leonard Kleinrock Oral History