Adaptive Link Rate (ALR) — Power-Efficient Ethernet Links

(Note: Also called Energy Efficient Ethernet (EEE))

Opportunity

Today, most Ethernet links never vary the rate at which data is transmitted, even if very little data is moving along the link.  As higher data rates require dramatically more power, increasing energy is being used to transmit small amounts of data most of the time. While it is possible to change the speed of a link—and some computers do when going to sleep or turning off—the process is far too slow to be used while products are idle or active.

Solution

Substantial energy savings will result from being able to quickly switch the speed of network links in response to the amount of data that is being transmitted.  We call this adaptive link rate (ALR), and are presently working with the Ethernet Alliance and the IEEE 802 standards committee to develop this into a standard.  It is already part of the Tier 2 requirements for the ENERGY STAR computer specification.

A description of the concept and potential of Adaptive Link Rate can be found on the Ethernet Alliance page for White Papers as Improving the Energy Efficiency of Ethernet: Adaptive Link Rate Proposal.

The IEEE 802.3 Energy Efficient Ethernet Study Group actively worked on this technology from January through September, 2007.  The work is now being done by the IEEE 802.3az Task Force (web link forthcoming).

Contact

• Mike Bennett
• (510) 486-7913