Direct measurement of the accuracy of clock synchronisation algorithms

In a distributed system, no hardware facilities exist to synchronise the clocks of the computers within the system. Clock synchronisation algorithms designed to synchronise clocks in a distributed system have been the subject of much research. The lack of a global clock has meant that the accuracy of these algorithms has been assessed using indirect measures of clock offsets. As part of our work on clock synchronisation, we have developed a clock synchronisation test bed that allows for direct measurement of clock offsets. The test bed has both hardware and software components. Careful design has made the test bed inexpensive and easy to construct. The first implementation of the test bed is largely complete.