A hybrid energy saving strategy with LPI and ALR for energy-efficient Ethernet

In this paper, by combining the schemes of Low Power Idle (LPI) and Adaptive Link Rate (ALR), we propose a hybrid energy saving strategy for IEEE 802.3az energy-efficient Ethernet (EEE). In this hybrid energy saving strategy, links will transfer to the sleep mode from the active mode as soon as there are no packets ready for transmission. Namely, the link will become idle once the output buffer becomes empty. In the active mode, the link transmission rate is adaptively adjusted based on the number of packets in the output buffer with two thresholds: the Lower Threshold and the Higher Threshold. We model the system operation by using a discrete time multiple vacation queue with adaptive service rates. By using the method of a matrix geometric solution, we analyze this system model in the steady state, and obtain the formulas for the performance measures in terms of the energy saving ratio and the average latency of packets. Moreover, we provide numerical results with analysis and simulation to investigate the influence of the system parameters on the system performance.