A comparison of improving multi-class imbalance for internet traffic classification

Most research of class imbalance is focused on two class problem to date. A multi-class imbalance is so complicated that one has little knowledge and experience in Internet traffic classification. In this paper we study the challenges posed by Internet traffic classification using machine learning with multi-class unbalanced data and the ability of some adjusting methods, including resampling (random under-sampling, random over-sampling) and cost-sensitive learning. Then we empirically compare the effectiveness of these methods for Internet traffic classification and determine which produces better overall classifier and under what circumstances. Main works are as below. (1) Cost-sensitive learning is deduced with MetaCost that incorporates the misclassification costs into the learning algorithm for improving multi-class imbalance based on flow ratio. (2) A new resampling model is presented including under-sampling and over-sampling to make the multi-class training data more balanced. (3) The solution is presented to compare among three methods or to compare three methods with original case. Experiment results are shown on sixteen datasets that flow g-mean and byte g-mean are statistically increased by 8.6 % and 3.7 %; 4.4 % and 2.8 %; 11.1 % and 8.2 % when three methods are compared with original case. Cost-sensitive learning is as the first choice when the sample size is enough, but resampling is more practical in the rest.