**Fast, Memory Efficient Flow Rate Estimation Using Runs**,

*Fang Hao, Murali Kodialam, T.V. Lakshman, Shantidev Mohanty*, in IEEE/ACM Transactionson Networking, Vol. 15, No. 6, December 2007.

The paper suggests to estimate the rate of flows by basically looking indirectly at the flow rate. The quantity is the number of 2-runs, that is the number of time that consecutive arrivals belong to the same flow. The occurrence of a 2-run will depend on the rate of the flow, and from observing the flows during a long enough time, one can infer the fraction of traffic belong to a flow by counting the two-runs.

This is similar in concept to the Flageolet & Martin paper, which observes some metric which is derived from the underlying process. F&M toss a geometric random variable and keep the max every time a flow works through the system; while this paper considers another derivative function of the rate. I believe I have seen a version of F&M used for the purpose of this paper, which seems natural.

The idea is cute, and leads to some straightforward analysis of the accuracy of the method. I was curious about how the assumptions of the model (independent Poisson processes for each flow, stationarity, etc.) would translate in a real link, but for a link with enough traffic, the method seems to work quite well.

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