Clock synchronization in virtual rings

A probabilistic algorithm for external clock synchronization is proposed. The algorithm works under the assumption that it is possible to identify a virtual ring among the servers involved, and does not require an upper bound to message transmission delays. The approach is probabilistic, since clock synchronization is not guaranteed, but the probability of success can be made arbitrarily close to one. The precision is comparable with that achievable with other probabilistic protocols, with the advantage that all the nodes can synchronize their clocks within the same attempt. A Pascal-like description of the protocol is given, and a formal proof of its correctness is outlined