Nick Duffield holds a B.A. in Natural Sciences (Physics and Theoretical Physics, 1982) and the Certificate of Advanced Study in Mathematics (1983) from the University of Cambridge, U.K. He was awarded a Ph.D. (1987) by London University, U.K., for a study of dynamics and stability of non-equilibrium phase-transitions in biological systems. He held postdoctoral positions in Heidelberg, Germany, and Dublin, Ireland, before joining the faculty of the School of Mathematical Sciences in Dublin City University, Dublin, Ireland in 1991. He moved to AT&T Labs-Research in 1995, where he is Technology Leader in the Network Management and Performance Department. His current research focuses on performance measurement, inference and analysis of communications networks. He is active in the IETF and was charter Chair of its working group on Packet Sampling.