Efficient bandwidth allocation and low delays remain important goals, expecially in high-speed networks. Existing end-to-end congestion control schemes (such as TCP+AQM/RED) have significant limitations to achieve these goals. In this paper, we present a new and simple congestion control scheme called Load Early Detection (LED), that achieves high link efficiency and low persistent queue length. The major novelty of LED is that it gauges the congestion level by measuring the traffic load instead of the queue length. We show analytically that this feature of LED enables it to detect congestion earlier and react faster than other schemes. To gain insight into the behavior of LED and compare it with RED, we analyze a simple fluid model, and study the relation between stability and throughput, especially for low delays. We evaluate the performance of LED using extensive ns2 simulations over a wide range of network scenarios. Our simulation results show that LED achieves significantly higher link efficiency than RED (up to 83%), REM (up to 141%), and PI controller (up to 88%), especially in the presence of low delays.
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