In
computer networking, Energy-Efficient Ethernet (EEE) is a set of enhancements to
twisted-pair
Twisted pair cabling is a type of wiring used for communications in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility. Compared to a single conductor or an untwisted ba ...
,
twinaxial
Twinaxial cabling, or "Twinax", is a type of cable similar to coaxial cable, but with two inner conductors instead of one. Due to cost efficiency it is becoming common in modern (2013) very-short-range high-speed differential signaling applicatio ...
,
backplane, and
optical fiber Ethernet physical-layer variants that reduce power consumption during periods of low data activity. The intention is to reduce power consumption by 50% or more, while retaining full compatibility with existing equipment.
The
Institute of Electrical and Electronics Engineers
The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operation ...
(IEEE), through the IEEE 802.3az task force, developed the standard. The first study group had its call for interest in November 2006, and the official standards task force was authorized in May 2007. The IEEE ratified the final standard in September 2010. Some companies introduced technology to reduce the power required for Ethernet before the standard was ratified, using the name Green Ethernet.
Some energy-efficient switch
integrated circuits were developed before the IEEE 802.3az Energy-Efficient Ethernet standard was finalized.
Potential savings
In 2005, all the
network interface controllers in the United States (in computers, switches, and routers) used an estimated 5.3 terawatt-hours of electricity.
According to a researcher at the
Lawrence Berkeley Laboratory, Energy-Efficient Ethernet can potentially save an estimated a year in energy costs in the U.S. Most of the savings would come from homes () and offices (), and the remaining from data centers.
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]
Concepts
The power reduction is accomplished in a few ways. In Fast Ethernet and faster links, constant and significant energy is used by the physical layer
In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer; The layer most closely associated with the physical connection between devices. This layer may be implemented by a PHY chip.
The ...
as transmitters are active regardless of whether data is being sent. If they could be put into sleep mode when no data is being sent, that energy could be saved.PHY
PHY is an abbreviation for the physical layer of the OSI model and refers to the circuitry required to implement physical layer functions.
PHY or Phy may also refer to:
* Phy, the drug methadone
* Phetchabun Airport (IATA code), Thailand
See al ...
. The PHY will then send LPI symbols for a specified time onto the link, and then disable its transmitter. Refresh signals are sent periodically to maintain link signaling integrity. When there is data to transmit, a normal IDLE signal is sent for a predetermined period of time. The data link is considered to be always operational, as the receive signal circuit remains active even when the transmit path is in sleep mode.
Green Ethernet
Green Ethernet technology was a superset of the 802.3az standard. In addition to the link load power savings of Energy-Efficient Ethernet, Green Ethernet works in one of two ways. First, it detects link status, allowing each port on the switch to power down into a standby mode when a connected device, such as a computer, is not active. Second, it detects cable length and adjusts the power used for transmission accordingly. Standard switches provide enough power to send a signal up to . However, this is often unnecessary in the SOHO environment, where of cabling are typical between rooms. Moreover, small data centers can also benefit from this approach since the majority of cabling is confined to a single room with a few meters of cabling among servers and switches. In addition to the pure power saving benefits of Green Ethernet, backing off the transmit power on shorter cable runs reduces alien crosstalk, and improves the overall performance of the cabling system.
Green Ethernet also encompasses the use of more efficient circuitry in Ethernet chips, and the use of offload engines on Ethernet interface cards intended for network servers.
See also
* Green computing
* One Watt Initiative
* Power over Ethernet (PoE)
* Autonomous peripheral operation
References
External links
IEEE P802.3az Energy Efficient Ethernet Task Force
* Blog for Energy-Efficient Ethernet techniques and news analyses, circa 2009.
{{Ethernet
IEEE 802
Ethernet
Energy conservation
Computers and the environment