This article is part of our series highlighting IEEE Fellows in celebration of the Fellow program's 50th-anniversary year.
The Internet of Things—moving to 1 trillion interconnected devices by 2022—would not have been possible, to say nothing of the original Internet, without the contributions of four IEEE Life Fellows: Paul Baran, Vinton Cerf, Robert Kahn, and Leonard Kleinrock. They were instrumental in developing parts of the predecessor to the Internet, known as the ARPANET. That communications network was named after the funding organization within the U.S. Department of Defense, the Advanced Research Projects Agency (or ARPA, now known as DARPA after “Defense” was added to its name).
The ARPANET was originally intended for connecting universities and research laboratories. The IEEE Fellows invented packet switching, the basic technique for sending data over the Internet, and TCP/IP, the communication protocols that form the backbone of how the Internet works. Bolt, Beranek, and Newman—BBN for short—a high-technology company in Cambridge, Mass., that provides research and development services, was responsible for implementing the very first version of the new network.
While at Rand Corp., in Santa Monica, Calif., in the early 1960s, Baran developed the fundamentals of packet switching, which sends data in discrete bundles that he called “message blocks.” Each block would be sent separately over a network—the exact path did not matter—and reassembled at the destination. This method also involves a rapid store-and-forward design. When a node receives a packet, it stores it, determines the best route to its destination, and then sends, or forwards, it to the next node on that path. If a problem occurred with a node, packets would be routed around it. Baran was elevated in 1993 to Fellow “for pioneering packet switching and other advances in the art of electronic communication.”
As an MIT graduate student in the early 1960s, Kleinrock worked on queuing theory, the mathematical study of waiting in lines (or queues) as it applied to packet-switching networks. He developed the theory as a way to handle the burst-like nature of computer data transmission and its resulting inefficiencies. After graduating, he joined the faculty of the University of California, Los Angeles, where he tested his theory. In September 1969, his UCLA team connected a computer to an Interface Message Processor (IMP), which became the first node on the ARPANET. A month later, he supervised the transmission of the first message ever sent over the network. By the end of the year, the ARPANET was operating among four university nodes: at UCLA; University of California, Santa Barbara; University of Utah; and Stanford University’s Research Institute.
For his contributions to computer-communication networks, queuing theory, time-shared computer systems, and engineering education, Kleinrock was named Fellow in 1973.
As a graduate student at UCLA, Cerf was a member of Kleinrock’s network working group. In addition to connecting the first nodes of the ARPANET, the group developed host-to-host protocols, email, and the higher-level protocols like Telnet for remote access and the file-transfer protocol, better known as FTP. Cerf became the lead developer of the host software used to inject traffic into the network as well as test it. Through his work, Cerf met Kahn, who worked at BBN and helped develop IMP.
After graduating, Cerf joined Stanford in 1972 as an assistant professor. There he developed the Network Control Program protocol and conducted research on packet network interconnection protocols. In 1973 he and Kahn, who in 1972 had joined the DARPA Information Processing Technology Office, teamed up to work on the network’s next-generation protocol. The two invented the fundamental communication protocols now at the center of the Internet: the Transmission Control Protocol (TCP) and the Internet Protocol (IP), later shortened to TCP/IP. These protocols connected the diverse computer networks that were part of the Internet.
Cerf and Kahn wrote the seminal paper on the design of the Internet and its TCP protocols, published in IEEE Communications Magazine in May 1974.
In 1988, Cerf was elevated to Fellow “for contributions and leadership in the design, development, and application of Internet protocols.”’
Kahn also played a major role in forming the basis of open-architecture networking, which allows computers and networks all over the world to communicate with one another, regardless of the hardware or software the computers use. In 1972 Kahn demonstrated the ARPANET at the International Conference on Computer Communications, held in Washington, D.C. For the demonstration, BBN installed a terminal interface processor with an augmented IMP in the venue’s basement and linked nearly 60 types of terminals.
In 1981, he was named Fellow “for original work in packet switching mobile radio telecommunications technology.” The technique was used for organizing computer resources into computer communications networks. In 1989, the name ARPANET was retired and replaced by today’s “Internet.”