Robert Kahn (computer scientist)

Robert Elliot Kahn (born December 23, 1938) is an American electrical engineer. Together with Vint Cerf, he was the first to put forward the Transmission Control Protocol (TCP) and the Internet Protocol (IP), the core communication protocols that underlie the Internet. In 2004, Kahn and Cerf shared the Turing Award for their TCP/IP work.

Kahn was born in Brooklyn, New York City, in December 1938 to Beatrice Pauline (née Tashker) and Lawrence Kahn, an Ashkenazi Jewish family. Through his father, he is a relative of futurist Herman Kahn. He earned a bachelor’s degree in electrical engineering from the City College of New York in 1960, then went to Princeton University, where he received an M.A. in 1962 and a Ph.D. in 1964, both in electrical engineering. At Princeton, his advisor was Bede Liu, and his doctoral dissertation was titled “Some problems in the sampling and modulation of signals.”

Kahn began his career at Bolt Beranek and Newman Inc., where he was the lead designer of the ARPANET. In the fall of 1972, he demonstrated the ARPANET by connecting 20 different computers at the International Conference on Computer Communications (ICCC)—an event widely seen as the moment that proved packet switching was a real technology. In 1972, he joined the Information Processing Techniques Office (IPTO) at DARPA. There, he helped develop the TCP/IP protocols for linking diverse computer networks. After becoming director of IPTO, he launched the U.S. government’s billion-dollar Strategic Computing Initiative, the largest computer research and development program ever undertaken by the federal government. After thirteen years at DARPA, he left in 1986 to found the Corporation for National Research Initiatives (CNRI), where as of 2022 he remains chairman, CEO, and president.

While working on the SATNET satellite packet network project, Kahn first conceived the ideas that became the Transmission Control Protocol (TCP), intended as a replacement for the earlier ARPANET protocol NCP. TCP was key to forming the basis of internetworking—allowing computers and networks worldwide to communicate regardless of their hardware or software. To achieve this, TCP was designed with several features: small network subsections could talk to each other through specialized computers that only forwarded packets (initially called gateways, now routers); no single point of failure or central control existed; each piece of information got a sequence number to ensure correct ordering and detect loss; a sending computer would know a message was received when the destination sent back an acknowledgement (ACK); lost information would be retransmitted after a timeout detected the missing ACK; and each message carried a checksum, calculated by the sender and checked by the receiver, to detect damage en route. Vint Cerf joined the project in spring 1973, and together they completed an early version of TCP. Later, the protocol was split into two layers: TCP handled host-to-host communication, while IP handled internetwork communication. Together they are known as TCP/IP, a foundation of the modern Internet. In 1992, Kahn co-founded the Internet Society with Vint Cerf to lead Internet standards, education, and policy.

Kahn has received numerous honors. In 1981, he became an IEEE Fellow for original work in packet-switching mobile radio telecommunications. He was elected to the National Academy of Engineering in 1987 for research contributions in computer networks and packet switching, and for creative management of research in computers and communications. He was a Founding Fellow of the Association for the Advancement of Artificial Intelligence in 1990. He received the SIGCOMM Award in 1993 for visionary technical contributions and leadership in information systems technology, and shared the 2004 Turing Award with Vint Cerf for pioneering work on internetworking, including the Internet’s basic communications protocols, and for inspired leadership in networking. His other awards include the AFIPS Harry Goode Memorial Award, the Marconi Award, the ACM SIGCOMM Award, the ACM President’s Award, the IEEE Koji Kobayashi Computer and Communications Award, the IEEE Alexander Graham Bell Medal, the IEEE Third Millennium Medal, the ACM Software Systems Award, the Computerworld/Smithsonian Award, the ASIS Special Award, and the Public Service Award from the Computing Research Board. He has twice received the Secretary of Defense Civilian Service Award. He received an honorary degree from the University of Pavia in 1998. In 1999, he was awarded the Stibitz-Wilson Award from the American Computer & Robotics Museum for pioneering the Internet through major design and development contributions to the original ARPANET NCP protocol and co-inventing the Internet’s TCP/IP protocol. He is also a recipient of the 1997 National Medal of Technology, the 2001 Charles Stark Draper Prize from the National Academy of Engineering, and the 2002 Prince of Asturias Award.