In what is described as “the first detailed experimental evaluation of power consumption of [energy efficient Ethernet, EEE] switches,” this paper reveals in appropriate detail the extent to which three first-generation 802.3az-compliant devices deliver on the promise of reducing the carbon footprint when compared to a traditional, noncompliant device.

This study, which was partly funded by a Google Research Award, shows how the savings realized vary significantly with the port and traffic load, as well as the size and burstiness of the packets. Using these results, the researchers produced a simple model through which one can estimate the power consumption of small EEE-compliant switches typically found in home and small office settings. Interestingly, the power consumption of the tested gigabit switches maxes out when ports reach utilization rates of ten to 55 megabits per second (Mbps), well below the one gigabit per second (Gbps) limit, because of the reduced opportunity to enter the low power idle (LPI) mode defined by the standard. Once in LPI mode, however, the energy savings are significant.

Given an estimated collective savings potential of over two terawatt-hours (TWh)/year in the US alone, further research into the effectiveness of these devices should help promote widespread adoption. As the authors suggest, additional studies are required to evaluate the degree to which newer and larger switches are able to turn energy efficiency standards into real savings, and to more accurately assess the worldwide potential. This report is certainly a step in the right direction.