Patent ID: 8000396

Claim:
A filtering apparatus comprising: a plurality of first filters assigned first numbers different from each other and configured to detect packets having previously specified identifiers, respectively; a plurality of information registers disposed in correspondence with the first filters and configured to store a predetermined number of bits, respectively; a condition storage portion configured to store second numbers different from each other and section conditions associated with the second numbers; a plurality of second filters each assigned one of the second numbers and configured to connect with respective ones of the plurality of first filters and to check whether the packet detected by a respective first filter satisfies the section condition associated with the appropriate second number determined for the respective first filter; and a determination portion configured to determine a number range specifying a part of the second numbers for each first filter as not overlapping each other based on the first numbers of each first filter and select an appropriate second number from each number range per first filter based on values of bits in each information register, wherein the predetermined number of bits in each information register is less than the total number of second filters, and each of the plurality of first filters has a predetermined range of the plurality of second filters for which it is allowed to connect to, and the predetermined range for each of the plurality of first filters is different from each other.