Predicting short-transfer latency from TCP arcana: extended version

In some contexts it may be useful to predict the latency for short TCP transfers. For example, a Web server could auto-matically tailor its content depending on the network path to each client, or an “opportunistic networking ” application could improve its scheduling of data transfers. Several techniques have been proposed to predict the latency of short TCP transfers based on online measure-ments of characteristics of the current TCP connection, or of recent connections from the same client. We analyze the predictive abilities of these techniques using traces from a variety of Web servers, and show that they can achieve use-ful accuracy in many, but not all, cases. We also show that a previously-described model for predicting short-transfer TCP latency can be improved with a simple modification. Ours is the first trace-based analysis that evaluates these prediction techniques across diverse user communities.