More energy-efficient Ethernet - without the standards-making fuss

A student has come up with a method of making Ethernet switches more energy-efficient, a method that will work with current Ethernet switches using existing standards.

Last year, the Ethernet Alliance created a competition, the White Paper Challenge, which asked university students to "present solutions to further the progress of Ethernet technology and its practical usage." The winning paper was "PAUSE Power Cycle: A New Backwards Compatible Method to Reduce Energy Use of Ethernet Switches," by Francisco Blanquicet, a graduate student at the University of South Florida.

The paper acknowledges the work of the IEEE 802.3az Energy Efficient Ethernet Task Force, which is currently examining ways to cut power usage of Ethernet gear. However, that task force is looking to create a new standard that would need to be supported by the gear, while Blanquicet's paper describes a method that can be used today.

The method uses the IEEE 802.3 PAUSE flow control. Blanquicet writes: "It is during the periods in which the links are paused that components in the LAN switch such as PHY, MAC, and interconnects can be powered off, thus allowing for energy savings."

He proposes rapidly pausing and un-pausing Ethernet links, powering down the components during the pauses. The downside is that packets might be lost to buffer overflows, he says. The question then becomes, would the loss be enough for users to notice a delay?

He set up a test network and had seven test subjects rate their experiences, using different pause lengths ranging from 50 milliseconds to 300 milliseconds. They were happiest with 50 ms, though the ratings were still a bit off from the no-pause network scenario.

The paper is quite innovative, and it makes you wonder what other improvements could be made to our networks, using the standards that already exist.

Jeff Caruso is site editor at Network World.