Impact of flow dynamics on traffic engineering design principles

A common traffic engineering design principle is to select a small set of flows, that account for a large fraction of the overall traffic, to be differentially treated inside the network so as to achieve a specific performance objective. We illustrate that one needs to be careful in implementing such an approach because there are tradeoffs to be addressed that arise due to traffic dynamics. We demonstrate that Internet flows are very volatile in terms of volume, and may substantially change the volume of traffic they transmit as time evolves. Currently proposed schemes for flow classification, although attractive due to their simplicity, face challenges due to this property of flows. Bandwidth volatility impacts the amount of load captured in a set of flows, which usually drops both significantly and quickly after flow classification is performed. Thus if the goal is to capture a large fraction of traffic consistently over time, flows will need to be reselected often. Our first contribution is in understanding the impact of flow volatility on the classification schemes employed in a traffic engineering context. Our second contribution is to propose a classification scheme that is capable of addressing the issues identified above by incorporating historical flow information. Using actual Internet data we demonstrate that our scheme outperforms previously proposed schemes, and reduces both the impact of flow volatility on the load captured by the selected set of flows and the required frequency for its reselection.