A method is described that involves presenting packet header information from a packet and packet size information for the packet to a pipeline that comprises multiple stages. One of the stages identifies, with the packet header information, where input flow information for the packet is located. The input flow information is then fetched. The input flow information identifies where input capacity information for the packet is located and the input capacity information is then fetched. Another of the stages compares an input capacity for the packet with the packet's size and indicates whether the packet is conforming or non-conforming based upon the comparison. The input capacity is calculated from the input capacity information.