Ethernet standard to cut energy use

EEE-compliant network devices will add a "sleep" state that lets a transmitter shut down during periods of inactivity.

By Martin Rowe, Senior Technical Editor -- Test & Measurement World, 11/1/2010 12:00:00 AM

Reducing energy consumption is on everyone's mind these days, and engineers have developed a standard for Energy Efficient Ethernet, or EEE. The IEEE 802.3az standard, which was approved on September 30, provides a framework for engineers to design EEE-compliant products.

EEE-compliant network devices will add a "sleep" state that lets a transmitter shut down during periods of inactivity. The addition of a sleep state adds complexity to Ethernet devices, test equipment, and test procedures.

A paper by Jeff Lapak and Jon Beckwith, senior engineers at the University of New Hampshire InterOperability Laboratory, explains the testing challenges in detail. (Download "Energy Efficient Ethernet brings on testing challenges").

Read more from the November 2010 issue.

Lapak and Beckwith highlight new problems you will face when testing EEE-compliant products, especially while dedicated software for test equipment is unavailable. Oscilloscopes will need to capture and measure timing on the relatively short signals that will occur during silent periods. EEE-compliant devices must complete a negotiation stage to establish if the node at the other end of a link is also EEE compliant. You will need to capture those negotiation signals and analyze them for timing, jitter, and amplitude.

In some instances of EEE, you will have to remove jitter from parts of your measurements. You will need to either do this in real time or capture the signals and perform post-process analysis. In addition, you will have to verify that an EEE device doesn't enter sleep state incorrectly.

You will also need to measure power consumption using real-world traffic conditions. Simply measuring the energy savings between full traffic and no traffic doesn't represent the energy savings that will occur under real-world traffic conditions.