Improving Energy Efficiency in IEEE 802.3ba High-Rate Ethernet Optical Links

Energy efficiency in communications, and particularly Ethernet, is becoming an important research area. The IEEE 802.3az energy-efficient Ethernet standard has already proposed a mechanism to reduce energy consumption on copper-based physical layer devices. This mechanism exploits the well-known fact that end-user links are usually lightly loaded, and that important energy savings can be achieved, if the device is put into a low-power sleep-mode whenever no frames are pending for transmission. This study pursues a two-goal purpose: firstly, it aims to evaluate whether such an active/sleep dual-state mode is suitable for high-rate optical Ethernet links as defined in the upcoming IEEE 802.3ba amendment that specifies the lower layers of 40- and 100-Gigabit Ethernet. Secondly it proposes to use an algorithm that dynamically exploits the multilane architecture of the high-speed optical transport layer. As it is studied throughout the paper, the two-state active/sleep-based mechanism may not achieve energy savings, while a load-based dynamic lane management enables energy reductions for a wide range of input traffic loads. A commercially available 100GBASE-SR10 module is used as case study for the analysis.