Virtual process clock: ATM performance measurements on UNIX workstations

We present a model for accurately taking measurements of ATM network performance parameters from UNIX workstations. Specifically, we concentrate on measurements of round-trip delay and delay variation of ATM cells. We develop the concept of a virtual process clock (VPC) associated with every UNIX process. All measurements are taken with respect to this clock and we demonstrate that this substantially improves the “precision” and “accuracy” of measured parameters. We present experimental results that characterize VPC and also for the average cell delay and cell delay variation of ATM cells. We demonstrate that VPC is also fundamental in the synchronization of UNIX hardware clocks on a network