ESTIMATING MULTIPLE DISTINCT-FLOW COUNTS IN PARALLEL

A network switch includes circuitry, multiple ports and multiple hardware-implemented distinct-flow counters. The multiple ports are configured to receive packets from a communication network. Each of the multiple hardware-implemented distinct-flow counters is configured to receive (i) a respective count definition specifying one or more packet-header fields and (ii) a respective subset of the received packets, and to estimate a respective number of distinct flows that are present in the subset, by evaluating, over the packets in the subset, a number of distinct values in the packet-header fields belonging to the count definition. The circuitry is configured to provide each of the distinct-flow counters with the respective subset of the received packets, including providing a given packet to a plurality of the distinct-flow counters, and to identify an event-of-interest based on numbers of distinct flows estimated by the distinct-flow counters.