He received the B.Sc. degree in Mathematics in 1970 from Athens University, Greece, the M.Sc. degree in Operational Research with Computing from Leeds University, England, in 1971, and the Ph.D. degree in Operations Research from Trinity College Dublin, Ireland, in 1975. He ahs held visiting faculty positions at INRIA, Rocquencourt, France (1979), NORTEL, Research Triangle Park, North Carolina (1988-89 and 1995-96) and University of Paris 6, France (1995-96, 2000, and 2002).

He has published numerous papers in the area of performance modeling of computer and communication systems, and he has organized several national and international conferences. He has also published two print books: "Queueing Networks with Blocking: Exact and Approximate Solutions," Oxford Press 1994, "An Introduction to ATM Networks," Wiley 2002, and an e-book "Computer Simulation Techniques - The Definitive Introduction," 2002 (available through his Web site).

In 1995, he founded the IFIP Working Group 6.3 on the "Performance of Communication Systems," and he was the chairman from 1995 to 2002. As of 2004, he is the chairman of the IFIP Working Group 6.10 on "Optical Networks," He is also a member of IFIP Working Groups 6.2, and 7.3, and an IEEE Senior Member. In addition, he is an associate Editor for the "Performance Evaluation" Journal, and the "Telecommunications Systems" Journal. His current research interests are in the area of optical networks. In his free time he likes to go sailing on the"Aegean," a Pearson 31!