Accurate software that can be reliably and inexpensively synchronised is essential for many aspects of networking, including passive network measurement, active probing based network measurement, and many real-time network applications. Best effort solutions using existing PC software clocks synchronised with the standard Network Time Protocol (NTP) algorithms are not robust enough, nor accurate enough for many purposes, whereas GPS-based synchronisation is money- and effort-intensive, and thereby infeasible for large scale measurement efforts with a large number of nodes.

In this talk a CPU clock counter (TSC register)-based software clock will be described that has many intrinsic advantages, thanks to the high performance of modern off-the-shelf hardware. Principles and algorithms enabling a robust, accurate synchronisation based on the existing NTP server network will be described and illustrated using four months of real data collected in four different host-server environments. The result is an alternative remote-synchronised software clock with substantially enhanced performance. In particular, its reliability should enable many network measurement and service functions to be performed that are not feasible at present, and substantially improve the reliability of existing measurements that rely on precise timing. The technique is relatively lightweight and requires no kernel modifications as such for implementation.

About the Presenter
Darryl Veitch has been working in networking and tele-traffic engineering for over 10 years. He has worked within academic, industrial, and government research organisations in Australia, France, Sweden and the USA. Darryl has worked extensively both in passive and active traffic measurement and modelling, at both the theoretical and practical "layers."