Professor David J. Farber, whose work on academic experimental computer networks helped define the evolution of the early internet, died on February 7 at age 91 (Peter Wayner/New York Times)

Professor David J. Farber, a researcher and professor, contributed to the evolution of the early internet through his work on academic experimental computer networks. He guided students who did groundbreaking work in connecting the world online. Farber died at 91.