Edge-based active queue management
In the paper, a new framework of active queue management, namely, edge-based active queue management (EAQM), is proposed. Conventional AQM schemes are required to be deployed at all routers in the network, and this involves significant upgrading to current drop-tail routers. The new approach only needs to modify th ee dge routers and at the same time provides similar or better performance as compared toconventional AQM schemes. Furthermore, EAQM can reduce the throughput bias against TCP connections with longer round trip times, and this cannot be achieved by current available AQM approaches. Active queue management (AQM) has been a very active research area in recent years. Many AQM mechanisms have been proposed, e.g., random early detection (RED) (1), random exponential marking (REM) (2), PI controller (3), adaptive virtual queue (AVQ) (4), state feedback control (SFC) (5), and virtual queue and rate-based scheme (VQR) (6). The main goals of these schemes are to reduce and stabilise queuing delay, avoid global synchronisation, and achieve high link utilisation. RED is a standard queue length based AQM that drops packets with probability proportional to the current average queue length. AVQ is a typical rate based scheme. REM, PI, and SFC use the queue length and the aggregate flow rate to compute the dropping probability. VQR uses both the virtual queue length and aggregate flow rate to determine the dropping probability. AQM schemes have not been widely deployed in the current Internet because all the proposed AQM schemes need to be implemented in all routers (or at least bottleneck routers), and this demands significant upgrading to routers in the current networks. Another reason is that the performance of these AQM schemes have not been fully investigated and understood, and it is not clear which scheme performs the best. Therefore, it is still risky to deploy them in the entire network. In this paper, we propose the framework of edge-based AQM (EAQM). EAQM is only deployed at the network edge, and the drop-tail core routers are kept unchanged. Compared with traditional AQM schemes, it is able to provide comparable or even better performance; thus, it is more practical and economically feasible. It is well known that TCP's throughput is inversely proportional to the round trip time (RTT); considerable unfairness occurs to TCP connections with longer RTTs. As one of the key features, EAQM alleviates this type of unfairness, while current available AQM schemes fail to do so. 2 Framework of EAQM