Improving packet classification for multimedia applications in DiffServ architecture

To provide differentiated quality of service, packet classification is important for determining which flow an incoming packet belongs to so as to decide what service quality it should receive. Packet classification is essentially a problem of multidimensional range matching. Tuple space search is a well-known solution based on multiple hash accesses for various filter length combinations. Tuple pruning algorithm is a tuple-based algorithm which is able to achieve good performance in a practical environment; however, its worst-case speed is not guaranteed. We explore the relative property of filters and reorganize the filters through filter conversion. As compared with the tuple pruning algorithm, the proposed scheme can significantly improve the worst-case performance. Experimental results on both real-world and synthetic filter databases show that the worst-case lookup speed of the proposed scheme is 9 to 31 times faster than that of the tuple pruning algorithm.