Louis Pouzin’s contributions to the development of computer communications have been significant both as a research scientist and as a leader in the areas of network architecture and international protocol development. His achievements often placed him at odds with government and business entities vested in the technology of the day, but some of his key ideas have survived to become founding principles of today’s Internet.
Pouzin attended École Polytechnique and worked for the French computer company Bull, managing a team of software engineers, before traveling to the US to work at MIT on their first large scale time-sharing system (CTSS). For this system, he wrote a program for simplifying commands (RUNCOM) that he termed a ‘shell’ program, which became a forerunner of an entire class of command language programs. After returning to France, Pouzin was chosen to lead a government sponsored networking project to help promote the country’s computer industry. Before starting the project, Pouzin traveled back to the US to meet with key developers of Arpanet who shared with him lessons they had learned building their newly operational network. Pouzin returned to France with ideas for improvements. Based on theoretical simulation studies by Donald Davies at NPL, and on his own predilection for simplicity, Pouzin designed the CYCLADES network, as it became known, without the need for IMP hardware over a subnet. He used a new idea of packet switching, a packet he coined a “Datagram”, that could be sent over PTT provided telephone circuits.
While the French government stopped funding the CYCLADES program in the late ‘70’s, and the network went offline in 1981, the concepts Pouzin had implemented were heavily influential in the development of future Internet architecture, especially the TCP/IP protocols. While their decision to abandon CYCLADES left the French on the sidelines in the future development of the Internet, Pouzin’s vision of a simplified method for connecting diversified networks together contributed greatly to its future design.
I was able to meet with Pouzin at a busy restaurant in Ft. Lauderdale, FL. A gracious and polite man, Pouzin talked freely about his work and past. I enjoyed our brief time together and I hope I have asked questions that help clarify his considerable contributions.
Keywords: Time-sharing computer systems, MIT, CTSS, RUNCOM, CYCLADES, Datagram, TCP/IP