Synchronising Software Clocks on the Internet

Friday, January 16, 2004 - 1:30pm - 2:20pm
Keller 3-180
Darryl Veitch (University of Melbourne)
Accurate software clocks in PCs which can be reliably and inexpensively synchronised are essential for many aspects of networking, including 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. In this talk a CPU clock counter (TSC register) based software clock will be described which 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 4 months of real data collected in 4 different host-server environments. The result is an alternative remote-synchronised software clock with substantially enhanced performance.