Back to top

Hubert Zimmerman

Hubert Zimmerman

Hubert Zimmerman played a key role in the development of early networking standards and protocols at a time when many countries were developing their own networking projects. He is most widely known for his efforts in establishing the OSI Reference Model as a standard for networking communications. While his technical understanding of the problems at hand was essential, so too was his ability to sense and understand the political and economic forces at play in an arena where so many disparate interests butted heads.

Educated at École Polytechnique and Ecole Nationale Supérieure des Telecom, Zimmerman began his career doing research on operating systems for the Institut National de Recherche en Informatique et Automatique (INRIA). His work contributed to the development of the ChorusOS operating systems. While at INRIA, he worked closely with Louis Pouzin on the development of France’s CYCLADES network. In 1980, he moved to the research laboratory of the French Postes, Télégraphes et Telephones (PTT), the Centre National d’Etudes des Telecommunications (CNET). In 1987, he co-founded Chorus Systems with Michel Gien to commercialize ChorusOS.

As an early member of the International Network Working Group (INWG), Zimmerman contributed to the effort of establishing a datagram oriented Host-to-Host protocol standard. In IFIP working group 6.1, he collaborated with Vint Cerf, Roger Scantlebury and Alex McKenzie to write a version of End-to-End protocol that was adopted by networks throughout Europe, though it would not be adopted by the Arpanet community, who were by that time heavily invested in the development of TCP. Between 1978 and 1984, Zimmerman was instrumental in the development and eventual ISO approval of the OSI Reference Model as an international standard for the layering of data communication protocols. Though there was strong opposition to making a theoretical model an international standard, Zimmerman foresaw the value of establishing agreement on the basic underlying architecture for future protocols. Motivated by what he had learned from earlier standards making efforts, Zimmerman’s persistence and leadership proved essential in the eventual adoption of the OSI Reference Model. As Charles Bachman, the chair of ISO sc16 described of Zimmerman, “he was one of the very most important people on that committee, maybe the most important person, in terms of the contributions to it.”

To interview Zimmerman, I took a cab to the commercial area of Paris, where Chorus Systems was headquartered. The windows in his office commanded a dramatic view of Paris. After his helpful interview, I took the Métro back to my hotel near Hyde Park.

Keywords: INWG, IFIP, OSI, ISO, End-to-End protocol, TCP/IP

Hubert Zimmerman Interviewed by James Pelkey 5/25/88