A device includes a multistage filter and an elephant trap. The multistage filter has hash functions and an array. The multistage filter is operable to receive a packet associated with a candidate heavy network user and send the packet to the hash functions. The hash functions generate hash function output values corresponding to indices in the array. The elephant trap is connected to the multistage filter. The elephant trap includes a buffer and probabilistic sampling logic. The probabilistic sampling logic is operable to attempt to add information associated with the packet to the buffer a particular percentage of the time based in part on the result of the multistage filter lookup. The buffer is operable to hold information associated with the packet, counter information, and timestamp information.