Green Ethernet is a common name for a set of features that is designed to be environmentally friendly, and to reduce the power
consumption of a device. Green Ethernet is different from EEE in that Green Ethernet energy-detect is enabled on all devices
whereas only Gigabyte ports are enable with EEE.
The Green Ethernet feature can reduce overall power usage in the following ways:
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Energy-Detect Mode—On an inactive link, the port moves into inactive mode, saving power while keeping the Administrative status
of the port Up. Recovery from this mode to full operational mode is fast, transparent, and no frames are lost. This mode is
supported on both GE and FE ports. This mode is disabled by default.
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Short-Reach Mode—This feature provides for power savings on a short length of cable. After cable length is analyzed, the power
usage is adjusted for various cable lengths. If the cable is shorter than 30 meter for Tengigabit ports and 50 meter for other
type of ports, the device uses less power to send frames over the cable, thus saving energy. This mode is only supported on
RJ45 ports; it does not apply to Combo ports. This mode is disabled by default.
In addition to the above Green Ethernet features, the 802.3az Energy Efficient Ethernet (EEE) is found on devices supporting
GE ports. EEE reduces power consumption when there is no traffic on the port. EEE is enabled globally by default. On a given
GE or FE port, if EEE is enabled, the short reach mode must disabled. Similarly, the user must disable EEE before enabling
short reach mode. On XG interfaces, short reach is always enabled and there is no restriction on EEE settings. These modes
are configured per port, without taking into account the LAG membership of the ports.
The device LEDs are power consumers. Since most of the time the devices are in an unoccupied room, having these LEDs lit is
a waste of energy. The Green Ethernet feature enables you to disable the port LEDs (for link, speed, and PoE) when they are
not required, and to enable the LEDs if they are needed (debugging, connecting additional devices etc.).
Power savings, current power consumption and cumulative energy saved can be monitored. The total amount of saved energy can
be viewed as a percentage of the power that would have been consumed by the physical interfaces had they not been running
in Green Ethernet mode. The saved energy displayed is only related to Green Ethernet. The amount of energy saved by EEE is
not displayed.