Abstract: A system and method for estimating the traffic rates of large traffic sources is provided. A class of a most recently selected address is compared to the contents of a register. If the class is the same as the contents of the register, a first counter is incremented; otherwise, the class is loaded into the register and the first counter is initialized. A class of a new most recently selected address is then obtained and the above process repeated. If the count of the first counter reaches a predetermined threshold, a threshold counter associated with the class is incremented and the first counter and register are reset. A different threshold counter is associated with each different class. After a predetermined time period, the traffic rate for a class may be computed from the count of the threshold counter associated with the class.