PACKET CLASSIFICATION ENGINE

Packet classification apparatus includes a rule memory and a criterion memor y. One type of rule memory entry contains an operator and a pointer to a criterion memory entry. The operator defines a comparison operation to be performed, such as EQUAL (exact match) or LESS THAN. The criterion memory entry contains one or more values to be used as comparands on one side of the comparison, where corresponding values from a received packet appear on the other side of the comparison. Control logic responds to packet classification requests to retrieve a rule memory entry from the rule memory, retrieve the criterion memory entry identified by the criterion memory point er in the rule memory entry, and perform the operation specified by the operator in the rul e memory entry on the values in the criterion memory entry and corresponding values included in the classification request. This procedure is repeated for a sequence of rule memory entries until an ending condition is encountered, whereupon a packet classification result is generated reflecting the result of the classification operations. This resul t is provided to a packet processor to take the appropriate action based on the classification result.