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A Binary Feedback Scheme for Congestion Avoidance in Computer Networks

K.K. Ramakrishnan and Raj Jain, DEC

One-line summary: If router's avg queue length over some interval is >1, set a sticky "congestion bit" in IP-level header of an ACK, which will cause source to modify its window size. How quickly to react to changes in congestion-bit state, and by how much, are parameters arrived at by trial and error. Averaging interval is adaptively measured by observing repeated "busy+idle" cycles at each router. Resulting algorithm is fair, adapts quickly, and finds an efficient and stable operating point.

Overview/Main Points


Exploration of congestion as an "end to end visible property" of connectionless networks, and of a way to aggregate intermediate-router congestion information (though just 1 bit) by piggybacking on ACKs.


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