Augmenting the energy-saving impact of IEEE 802.3az via the control plane

IEEE 802.3az, the recent standard for Energy Efficient Ethernet, is one of the main contributions of the ICT industry to the global quest for energy efficiency. Energy consumption reduction is accomplished by essentially replacing the continuous IDLE of legacy IEEE 802.3 cards with a Low Power Idle. While this is an important step in the right direction, studies have shown that the energy saving with IEEE 802.3az highly depends on the traffic load and stops for link utilizations as low as 25%. In addition to the standardization effort for creating energy efficient networking hardware, several solutions have been proposed for energy efficient routing, OSPF in particular. However, most solutions are transparent to and usually leave open the question of how exactly are the energy savings realized in hardware. Simply routing less or no traffic through certain links will not automatically lead to those links consuming less energy. We present EAGER and CARE, two OSPF metrics customized for augmenting the energy saving of IEEE 802.3az line cards - the only available off-the-shelf, standard-complying hardware for saving energy in OSPF networks. The principle underlying the design of EAGER and CARE is that of creating a synergy between the control plane of OSPF routers and IEEE 802.3az compliant line cards, without requiring changes to the respective standards and/or the hardware. Simulation results show that EAGER and CARE can increase the amount of energy saved when using IEEE 802.3az line cards by 2× on a network of routers. Furthermore, the results show that CARE strikes a good balance between energy efficiency and traditional network performance metrics.