A posteriori Agreement for Fault-tolerant Clock Synchronization on
L. Rodrigues and P. Veríssimo
A shorter version of this report was published in the Digest of
Papers, The 22th International Symposium on Fault-Tolerant Computing,
July, 1992, Boston - USA.
We present a clock synchronization algorithm, dubbed a posteriori
agreement, based on a new variant of the well-known convergence
non-averaging technique. By exploiting an obvious characteristic of
broadcast networks, the effect of message delivery delay variance is
largely reduced. In consequence, the precision achieved by the
algorithm is drastically improved. Accuracy preservation is near to
optimal. Our solution, however, does not require the use of dedicated
Also available extended report (gzip postscript), (pdf) .