Achieving fair bandwidth allocation without per-flow state

In this paper, we present Queue Length based Fair Queueing (QLFQ), a scheme to approximate fair bandwidth allocation without per flow state. Edge routers divide each flow into a set of layers using a linear encoding scheme and insert an appropriate label into each packet header. Core routers maintain a dropping threshold at each router; packets with a label greater than the threshold are dropped. In order to determine the dropping threshold, we only need to know queue occupancy information and do few comparison operations in core routers (so we call our scheme Queue Length based Fair Queueing (QLFQ)). We have evaluated QLFQ together with CSFQ and RFQ with several different configurations and traffic sources. The simulation results show that QLFQ is able to achieve approximately fair bandwidth sharing in all of these scenarios. The performance of QLFQ is comparable to that of CSFQ, and it performs much better than RFQ.