Patent ID: 8213557

Claim:
A filtering apparatus comprising: at least one or more first filters assigned mutually different respective first filter numbers and used for first filtering to filter, from inputted packets, all or a part of the packets having a predetermined identifier; at least one or more connection information registers disposed in correspondence with the first filters and which are configured to retain information having a predetermined number of bits; at least one or more second filters assigned mutually different respective second filter numbers and used for second filtering to further filter, from all or a part of the packets filtered using the first filters, a data part of all or a part of the packets; a condition storage portion configured to store at least one or more types of filter conditions for identifying the data part associated to the second filters; one or more reference number registers configured to allocate an arbitrary number of the second filter numbers as a reference number to each of the first filter numbers and to store the each first filter number and the reference number allocated to each first filter number while associating the each first filter number with the reference number; and a determination portion configured to determine the second filter numbers to be used for the second filtering based on the reference number and values of the connection information registers corresponding to the first filters.