Measurement-based coalescing control for 802.3az

IEEE 802.3az standard (EEE), is the energy-aware alternative to legacy Ethernet. To save energy by extending the sojourn in the Low Power Idle state of EEE, packet coalescing has been proposed. While coalescing improves by far the energy efficiency of EEE, it is still far from achieving energy consumption proportional to traffic. Moreover, coalescing can introduce high delays. In this work, we use sensitivity analysis to evaluate the impact of coalescing timers and buffer sizes, and to shed light on the delay incurred by adopting coalescing schemes. Accordingly, we design and study measurement-based coalescing control solutions that tune the coalescing parameters on-the-fly, thus adapting the link to the instantaneous load and controlling the coalescing delay experienced by the packets. Our results show that, by relying on run-time delay measurements, simple and practical adaptive coalescing schemes outperform traditional static and dynamic coalescing. Notably, our schemes double the energy saving benefit of legacy EEE coalescing and allow to control the coalescing delay.