The topic of energy saving in Ethernet networks was already taken up by the IEEE in 2007. The working group founded for this purpose is IEEE 802.3az with the project name Energy Efficient Ethernet( EEE).
The activities are to be seen in the context of Green IT and are intended to reduce energy consumption in Ethernet by reducing and switching off certain transmission components. With Energy Efficient Ethernet (EEE), also known as Green Ethernet, power consumption is reduced when the port is switched off. With 802.3az EEE, power consumption is reduced when the port is active but there is no data traffic over the link. The feature can enable network components on both sides of the link to save power when there is no traffic. Network components with implemented 802.3az standard are fully compatible with existing network components.
802.3az EEE supports IEEE 802.3MAC operation at 100 Mbps and 1000 Mbps. It works with Link Layer Discovery Protocol( LLDP) to select the optimal set of parameters for the network components on both sides of a link. If LLDP is not supported by the link partner or is disabled, 802.3az EEE is still operational but may not be in the optimal mode of operation.