As part of Green IT, the IEEE has taken up the topic of energy savings in networks with the IEEE 802.3azworking group, Energy Efficient Ethernet (EEE). The IEEE 802.3az working group was established in 2006 and was tasked with developing a standard that would reduce energy requirements in Ethernet networks by 50% while maintaining full compatibility of all network components. This concept, also known as Green Ethernet, is about modifying the physical interfaces. This standard was adopted in 2010.
The concept addressed by 802.3az is about reducing the power requirements of networks during inactive transmission periods. Transmission protocols with which transmission rates and thus energy consumption were to be reduced with lower utilization were under discussion. However, the solution later implemented in the standard is based on switching off data transmission during inactive transmission times.
In data links, power is continuously required for the physical transmitters because they are constantly switched on. If there is no data traffic, the transmitters can be put into a sleep mode. During this time no energy is needed. To achieve this, the transmitters send a special control signal, the Low Power Idle( LPI), which indicates that the transmit chip can be turned off. The LPI signal is repeated periodically to update the sleep mode. As soon as data is transmitted, the stations send an idle signal with which the normal transmission state is established.
Switches that have implemented the 802.3az standard automatically adjust power consumption to the network load, thereby reducing power consumption by the 50% value specified in the standard.