, Volume 3, Issue 3, pp 146-158

Probabilistic clock synchronization

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A probabilistic method is proposed for reading remote clocks in distributed systems subject to unbounded random communication delays. The method can achieve clock synchronization precisions superior to those attainable by previously published clock synchronization algorithms. Its use is illustrated by presenting a time service which maintains externally (and hence, internally) synchronized clocks in the presence of process, communication and clock failures.

Flaviu Cristian is a computer scientist at the IBM Almaden Research Center in San Jose, California. He received his PhD from the University of Grenoble, France, in 1979. After carrying out research in operating systems and programming methodology in France, and working on the specification, design, and verification of fault-tolerant programs in England, he joined IBM in 1982. Since then he has worked in the area of fault-tolerant distributed protocols and systems. He has participated in the design and implementation of a highly available system prototype at the Almaden Research Center and has reviewed and consulted for several fault-tolerant distributed system designs, both in Europe and in the American divisions of IBM. He is now a technical leader in the design of a new U.S. Air Traffic Control System which must satisfy very stringent availability requirements.