Speeding up TCP/IP: Faster Processors are not Enough

Over the last decade we have been witnessing a tremendous increase in the capacities of our computation and communication systems On the one hand processor speeds have been increasing exponentially doubling every months or so while network bandwidth has followed a similar if not higher rate of improvement doubling every months or so Unfortunately applications that communicate frequently using standard protocols like TCP IP do not seem to improve at similar rates In our attempt to understand the magnitude and reasons for this gap between processor perfor mance and interprocess communication performance we study the execution of TCP IP on several processors and operating systems that span a time interval of more than eight years To be able to compare the performance of such di erent platforms we de ne mileage a new performance metric that shows how e ective is each platform in using processing power to transfer data We also pro pose calibrate and experimentally validate a simple model that can accurately characterize TCP IP performance of a computer based on its processor speed and memory bandwidth The main conclusion of this paper is that TCP IP performance does not scale comparably to processor speeds To make matters worse this poor scalability is magni ed and propagated to higher level protocols like HTTP