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New Energy Efficient Ethernet standard can save 80% on network power – UNH-IOL

Tony Chan | August 2, 2010 | 0 Comments

A new technology that can save as much as 80% on Ethernet networks is now being finalised by the industry. The new standard, called Energy Efficient Ethernet or EEE – also dubbed IEEE 802.3az, brings in a feature called, “low power idle mode,” which allows network equipment to save energy when no carrying traffic.

According to Jeff Lapak, senior engineer for the University of New Hampshire’s InterOperability Laboratory (UNH-IOL), the current Ethernet protocol maintains a constant link between devices that allows users instant connectivity, but at the cost of high energy consumption.

“The main feature of EEE is called the ‘Low power idle mode.’ In effect, it allows devices to turn off their transmitters and send idle signaling periodically to save energy when there is no data traffic to send,” Lapak said. “This differs from most of the common Ethernet types that are always transmitting even when there is no data being sent. The periodic nature was chosen to ensure that the devices would be able to wake quickly and maintain reliable communications when leaving the low power idle mode.”

In so doing, EEE-enabled networks can save as much as 80% on energy consumption.

“While there is no specification in the standard for what the level of power saving should be, in the low power idle mode it is expected that devices will be able to save around 80 percent of the energy that they would consume when operating normally. The overall power saving will depend greatly on the traffic utilization of the link,” Lapak said.

The 802.3az standard covers 100BASE-TX, 1000BASE-T, 10GBASE-T, 1000BASE-KX, 10GBASE-KX4, 10GBASE-KR, and also supports XGMII extension using the XGXS for 10 Gb/s PHYs.

“The standard is expected to be completed by 2011 and products that support the current draft of the standard are now being released,” Lapak said. “Energy efficiency is top of mind with our member companies and their customers so the pre-testing process will allow them to be able to deliver new solutions in the quickest possible timeframe.”

In the lead up to the final ratification of the standard, UNH-IOL is offering interoperability testing services for EEE devices to speed up time to market for equipment vendors.

“The largest challenges to interoperability will be ensuring that no data is lost when devices return to normal operations after being in low power idle mode. The Ethernet Alliance has already sponsored an interoperability event that was hosted by the UNH-IOL this April to test devices that were built to the draft standard,” he said. “Early interoperability testing like this will help to ensure that when the standard is finalized, devices will be able to interoperate.”

Another challenge is EEE’s ability to turn links on and off does add some latency to those connections, something that may affect precise timing requirements of Ethernet networks.

And while EEE equipment will be backwards compatible to existing Ethernet gear through the Auto-Negotiation process, both sides of a connection will have to support EEE in order to benefit from the energy saving feature.

However, the potential benefits from EEE extend far before just the networks themselves, Lapak said, adding that the EEE standard is a key component to other energy efficiency standards such as the EPA’s Energy Star program for server and data center energy efficiency.
“As the IT industry starts to adopt EEE, it could open the door for greater power savings as system operators can observe if the link has entered a low power idle state and begin to turn down or off other parts of the system where greater amounts of power are used,” he added.