An Optimal Internal Clock Synchronization Algorithm

We propose an optimal convergence function for achieving fault-tolerant, internal clock synchroniza, tion in the presence of arbitrary process and clock failures. The diflerential fault-tolerant midpoint convergence function guarantees an optimal maximum correction, an optimal maximum drift rate, and an optimal maximum deviation. The proposed convergence function is simple and easy to compute. It bounds the maximum drift rate of correct clocks by the maximum drift rate of a correct hardware clock. The maximum correction is limited by the maximum drift between two correct hardware clocks during one round. The maximum deviation is approximately 44 + ~PT,,, , where A is the maximum remote clock reading error, p is the maximum drift rate of a correct hardware clock and rman is the maximum duration of a synchronization round.