Patent ID: 7193997
Filing Date: 2007-03-20
Classification: H04L

Abstract:
1. A method for classifying a data packet in a data processing device to determine which of a plurality of predefined processing rules applies to the data packet, each said rule being associated with a range of possible data values in each of a plurality of dimensions corresponding to respective data items in the data packet, the method comprising: (a) for each dimension, identifying the corresponding data value in the packet and determining which of a set of predefined basic ranges contains that data value, wherein the basic ranges correspond to respective non-overlapping value ranges between successive rule range boundaries in that dimension; (b) for the basic range so determined for each dimension, selecting a corresponding basic range identifier from a set of predefined basic range identifiers corresponding to respective basic ranges in that dimension, wherein, for each of at least two dimensions, the basic range identifiers comprise respective p (c) combining the basic range identifiers for said plurality of dimensions to produce a search key; (d) supplying the search key to a ternary content-addressable memory; and (e) in the memory, comparing the search key with a set of prestored ternary rule vectors, each associated with a said rule and derived for that rule in dependence on the hierarchy for each of said at least two dimensions, to identify at least one rule which applies to the data packet.