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Engineers address need to curb CE power usage

Posted: 02 Apr 2007     Print Version  Bookmark and Share

Keywords:power consumption standards  consumer electronics standards  network switches 

Some of the same engineers who helped create power consumption standards for PCs and printers are turning their attention to network gear and CE. A team of researchers at Lawrence Berkeley National Laboratory hopes to suggest new power standards and practices for large network switches, wireless access points, STBs, home-control systems and other consumer gear as part of a two-year effort.

The lab's Energy Efficient Digital Networks initiative aims to reduce the estimated 200TWh of energy consumed annually in the U.S. by electronic devices, at a cost of some Rs.70,592 crore ($16 billion). The group—which is working with the Environmental Protection Agency's Energy Star programme and with academics at the University of South Florida—has already helped kick off a low-power standard for Ethernet. It expects to soon create a Website for its overarching initiative, which includes a handful of efforts, many of them not yet formally announced.

Proxy feature
Researchers think they could save as much as 10 per cent of the energy consumed by an average California home—70 of 700W—with a new proxy feature alone. With proxying, a network card or external network system could maintain a PC's presence on the Net while the computer goes into sleep mode.

The technique builds on work done a decade ago in approaches such as wake-on-LAN and directed packet filtering. Large businesses sometimes use those existing features on their private networks, but the techniques typically don't work well for consumers and smaller businesses. They often wake computers unintentionally or fail to wake them when needed. Internet routers often don't forward the so-called magic packets meant to wake up a PC.

"We are trying to define the functionality we want here and then get it into products," said Bruce Nordman, a principal research associate at Lawrence Berkeley Lab who oversees the work.

Once they have a proposal, researchers may turn to the Internet Engineering Task Force or the Distributed Management Task Force to make it a standard.

As underpinnings for a proxy feature, researchers are studying the distributed discovery protocol defined by the Universal Plug and Play Forum. They are also investigating a capability in the peer-to-peer (P2P) service run by Gnutella.

In a technical paper, University of South Florida researchers described a method for building smart network interface cards using a low-power MCU, along with Bloom filters and security techniques to radically compress the data needed for a proxy function. "We estimate that if only 25 per cent of PCs running P2P applications contained smart NICs with proxy capability, a savings of over Rs.375.02 crore ($85 million) per year in the U.S. could be achieved," the paper said.

Separately, Lawrence Berkeley Lab is in the process of selecting a few network systems for which it will suggest power consumption standards and test procedures. Large network switches for businesses as well as Wi-Fi access points and cable/DSL gateways for homes are likely to be the first targets. Once complete, the work will be handed off to the Energy Star programme. "Industry can help accelerate and approve this work at all stages," said Nordman. "We want to work with the industry from the get-go on all of this."

Lab researchers also hope to set similar standards for STBs, perhaps by building reference designs for low-power STBs. The Energy Star programme withdrew a power spec for STBs about two years ago when cable TV providers and STB makers could not reach a consensus on voluntary specs. However, the EPA is gearing up for another attempt, in hopes of launching an effort by this month.

Sleep state
More generally, the lab aims to push CE systems and standards from a two-state (ON/OFF) to a three-state (ON, sleep and OFF) model. The effort would set techniques to let OEMs automatically put systems in sleep or OFF states based on user activity. It would also empower consumers to understand and choose those states explicitly with new remote-control buttons.

The effort could involve changes to a wide range of consumer standards, including links such as infrared and HDMI. "We want to start a process that hopefully industry can take up. This will be an incremental effort over a number of years," said Nordman.

As another part of the programme, the lab helped kick off the Energy-Efficient Ethernet study group under IEEE 802.3. An inaugural meeting in mid-January attracted about 30 engineers from a cross section of chip and systems companies, including AMCC, Broadcom, Cisco, Hewlett-Packard, Intel and Nortel. "My initial impression is that it looks like there is enough interest in starting a project," said Mike Bennett, a networking engineer at Lawrence Berkeley Lab who chairs the study group.

According to IEEE rules, the group must submit a request to start a formal standard effort by June or ask for a six-month extension. Actually drafting a final standard could take another two years.

Several discussions have focused on finding a common mechanism to shift from 10Gbit to gigabit to 100Mbit Ethernet speeds without losing the link.

Remaining questions
Plenty of outstanding questions remain open, such as whether 100Mbps or 10Mbps speeds should be considered a floor and whether 1ms is a fast enough switching time for 10Gbit links. It's also unclear whether the standard would leave room for companies to compete on the basis of power consumed or switching speed. "I still haven't figured out where people may get a competitive edge here yet," said Bennett.

Backers estimate that Energy-Efficient Ethernet could save Rs.1,985.40 crore ($450 million) in energy costs a year in the U.S. alone.

Interestingly, the brunt of the savings—Rs.882.40 crore ($200 million)—could come from home computers, with another Rs.750.04 crore ($170 million) from offices and Rs.352.96 crore ($80 million) from data centres. Nordman estimates that a Gbit interface card could shave up to 1.5W off its power consumption and a 10Gbit card up to 10W by scaling back data rates at times of low traffic.

The EPA has already written draft) requirements for the 2009 version of its Energy Star programme mandating that "all computers shall reduce their network link speeds during times of low data traffic levels in accordance with any industry standards that provide for quick transitions among link rates."

Whether the IEEE can produce a standard and vendors ship products by then is not clear. "The timing will be challenging," said Nordman.

- Rick Merritt
EE Times




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