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Abstract

An Asynchronous Transfer Mode (ATM) switch (8) and method of operating the same to allocate Available Bit Rate (ABR) communications therethrough. The switch receives resource management (RM) cells over a sequence of measurement periods. A plurality of rate levels are defined, each associated with a measurement period of a corresponding duration; the measurement periods being nested. Saved and current values of the number of flows associated with each level, and saved and current values of the aggregate rates of these flows, are retained in memory. RM cells are received during the various measurement periods, and the various numbers and aggregate rates are maintained for each rate level, including the use of estimates for flows that have changed rate level. A bottleneck rate is determined as the larger of the ratio of ABR bandwidth to ABR flows, or the largest cell rate plus surplus bandwidth derived according to this sum. The bottleneck rate is then sent to the AT sources by backward-traveling RM cells, for adjustment of the ABR traffic.

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First Claim