Patent ID: 7801139

Claim:
A device having a field extractor for applying a plurality of masks to a portion of an incoming packet and extracting a corresponding plurality of fields from the portion of the incoming packet, the device comprising: a rules table in communication with the field extractor; and a combination table in communication with the field extractor, wherein each entry in the combination table includes an index, a hit rule and a miss rule; wherein the field extractor is configured to: use each of the plurality of fields to search the rules table; classify whether each search hit a rule in the rules table or missed all of the rules in the rules table; search the combination table for an entry whose index corresponds to the plurality of fields; and if a combination table entry is found, to select as a combination rule the hit rule if each of the plurality of fields hit a rule in the rules table and the miss rule if at least one of the plurality of fields missed all of the rules in the rules table; and to execute the combination rule.