Approved in September 2010, the Institute of Electrical and Electronics Engineers (IEEE) 802.3az Energy Efficient Ethernet standard likely is the final hurdle for 10GBase-T (10-Gbit/sec Ethernet over twisted-pair cabling) to overcome before enjoying widespread market deployment. As we first noted last December when commenting on the biggest cabling-industry stories of 2010, 10GBase-T deployment to some extent had been hanging on the finalization of 802.3az. Why? The biggest knock on 10GBase-T has been that it is a power hog, consuming multiple times the power per port of 10GBase-SR. 802.3az promises to change that.
When the IEEE announced the standard's ratification, the group stated it "provides network managers and everyday consumers of networking services with the tools they need to reduce energy consumption in network-attached devices, network routers and switches, computers and printers." Also at that time the Ethernet Alliance issued a statement on the new standard. The Alliance explained that 802.3az applies to a number of IEEE Base-T systems including 100Base-TX, 1000Base-T, 1000Base-KX, 10GBase-T, 10GBase-KX4 and 10GBase-KR. Also within the EEE specs was the creation of a new, lower-voltage 10-Mbit/sec connection 10Base-Te.
Michael Bennett, who chaired the IEEE P802.3az EEE Task Force and is a senior network engineer with Lawrence Berkeley National Labs, said, "Before this standard there was no industry-specified method for saving power on an Ethernet connection. While the power savings per link may be small, the cumulative effect in enteprise networks, data centers, home networking, et cetera can add up to terawatts saved annually, when the majority of existing Ethernet ports are replaced with EEE."
George Zimmerman, founder and chief technical officer of Solarflare who was technical chair of the Ethernet Alliance's EEE subcommittee, said, "The EEE protocol permits systems from multiple vendors to interoperate and greatly reduce power in underutilized links. The protocol provides faster recovery to high-bandwidth utilization while offering substantial power savings on low-utilized links. The EEE subcommittee looks forward to bringing together Ethernet Alliance members and non-members in performing interoperability testing and publishing those test results to accelerate the adoption of EEE in the industry."
Bennett further noted, "Minimizing energy-use is an ongoing battle, and there is always pressure on [information and communication technologies] managers to do more with less. The Energy Efficient Ethernet will save energy and lower operational expenses. The great advantage of using products supporting EEE is that there is no complex configuration necessary. In most cases, energy will be saved automatically. Saving energy in networked systems needs to be seamless and easy in order to achieve the greatest savings. IEEE 802.3az enables this ease of use through standards-based protocols."
The Ethernet Alliance described the five modes of operation that an EEE-enabled PHY will have.
- Active: Used for passing data across the link.
- Sleep: When the PHY is transitioning one of its paths into low-power idle (LPI)
- Quiet: When the path is operating in LPI.
- Wake: When the PHY is transitioning one of its paths out of LPI.
- Refresh: A periodic state during LPI in which the path wakes up to keep the clock circuitry and other parameters in synchronization before going back to LPI. Refresh permits a faster Wake time.
Watch video of Michael Bennett explaining the benefits of Energy Efficient Ethernet.