Patent ID: 7433357

Claim:
An apparatus for performing packet header lookup based on sequential lookup, the apparatus comprising: a header analyzer separating a header from a packet received via a network and outputting a lookup sequence about a field to be analyzed and having predetermined values of separated fields and a field included in one or more header combination rules; a unit lookup unit looking up matching the header combination rules with each field to be analyzed and input from the header analyzer based on the lookup sequence input from the header analyzer and outputting a match signal and a match address; a rule combination memory storing identification information for the header combination rules which use entries corresponding to the fields to be analyzed and reading out the identification information from a storage address which corresponds to the match address input from the unit lookup unit; a sequence combination memory storing lookup sequence information designated on fields constituting the packet header and sequence combination information that is information of lookup results for the field to which each header combination rule should refer and reading out read out sequence combination information to which the sequence combination information refer by using the sequence information assigned to entries contained in the fields to be analyzed as an input address; and a rule combination unit generating match results based on the match signal, identification information input from the rule combination memory, and sequence combination information input from the sequence information memory.