I'm looking for a tool to estimate file download times given a certain set of variables: file size, available bandwidth, latency, receive window and circuit utilization. To explain: Suppose I have a single OC3 serving FTP downloads to individuals all over the globe. If the OC3 is not heavily utilized *and* I know the bandwidth and latency between my FTP server and a client's workstation, I can make a rough estimate of how long it will take for a file of a particular size to download. I could create a matrix in Excel based on latencies and bandwidths (factoring in TCP receive window sizes) and that would give me a quick reference tool for gauging how long something should take to download given a fair number of scenarios. But what if I want to enhance such a matrix to factor in what happens to download times in those various scenarios as the utilization of that OC3 approaches 100%? I could make alot of edits to above mentioned Excel matrix....but that would get tricky and visually unappealing. Can anyone recommend a tool that makes it easy to play with the above variables...a sort of modeling tool not quite so fancy or expensive as Opnet for example? Maybe a webpage with a Java applet ? Or maybe a fancy Excel file? Thanks, BM