METHOD FOR PREPARING A DECISION TREE FOR PACKET PROCESSING

The invention relates to methods for processing data packets according to a set of rules, and especially for preparing of decision trees for selecting the correct rule for processing of a data packet. In preparation of a decision tree, a splitting point within a dimension being studied is chosen as follows. The rules are sorted to allow monotonous iteration through all range end values specified in the rules in the dimension being studied. The range end values are then iterated through in a monotonous fashion, either increasing or decreasing. At each iteration, the number of range low end values and the number of range high end values being equal to the current iteration value is counted. From these counts and the accumulated results from the corresponding counts in previous iterations, the numbers of rules with ranges in different positions relative to the current iteration value are deduced, and from these values, the goodness of the iteration value is calculated. After iteration of all range end values within the studied dimension, the iteration value with the best goodness is selected.