Energy-efficient Ethernet has arrived, with real savings

The No. 6 top sleeper tech story of 2010

Standards matter, but unless it's a new standard for Wi-Fi, the news that yet another has been ratified is usually a yawner. Not so with the adoption of the standard for energy-efficient Ethernet, or more formally IEEE 802.3az, which will lead to significant energy savings without a hit to performance or large up-front costs.

The new standard defines a protocol that lets two ends of an Ethernet network communicate only when they have packets to transfer. The protocol eliminates the overhead of typical administrative messages, allowing systems to stay in a sleep mode as much as 80 percent of the time.

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"Systems can go in and out of the idle state much faster, and spend much more time in the idle state as well," says Wael Diab, a technical director at Broadcom and vice chairman of the IEEE 802.3 Ethernet working group.

Individual switches are likely to cut energy usage by as much as 80 percent, but there will be savings throughout the entire network. That's because there's a multiplier effect as devices higher in the stack are signaled to go into a low-power state.

How much retrofitting will be required to take advantage of the new standard? Because the standard covers just the physical layer of the stack, only adapter cards and switching hardware need to be swapped. However, as future standards begin to reference this standard, more complex software and hardware options will come into play, University of New Hampshire senior engineer Jeff Lapak tells our sibling publication Network World.

LAN links generally average less than 10 percent utilization; even at peak times, the utilization does not reach 100 percent. When data is not being sent, the lower-speed switches stop transmitting and consume less power. However, the higher-speed switches (1000Base-T and 10GBase-T), the ones that are relevant to data centers, continue to transmit actively when there is no data to send, and thereby continue to consume power when idle.

According to Lepak, the 802.3az standard covers 100Base-TX, 1000Base-T, 10GBase-T, 1000Base-KX, 10GBase-KX4, 10GBase-KR, and the 10-Gigabit Media-Independent Interface (XGMII) extension using the 10-Gigabit Extended Extended Sublayer (XGXS) for the physical layer in the OSI network stack. What this means is that it will cover virtually all of the standard products in the office and home environments, such as laptop and desktop computers, servers, switches and routers, and home access devices.

In early December, Hewlett-Packard began shipping a family of network switches it claims are the first to comply with the new standard.

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The top underreported tech stories of 2010:

  1. Apple quietly became a key enterprise provider
  2. Server virtualization has stalled, despite the hype
  3. URL-shortening services gave hackers a new entry point
  4. The health care industry faces its risky ERP moment
  5. Deferred IT maintenance is a ticking time bomb
  6. Energy-efficient Ethernet has arrived, with real savings
  7. A major Internet security hole was finally plugged
  8. Social media messaging is getting around traditional firewalls
  9. Businesses are resisting the XBRL mandate

This article, "What you missed: Energy-efficient Ethernet has arrived, with real savings," was originally published at Get the latest insights in network technology issues and trends at


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