Cisco 500 Series Administration Manual page 197

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operational mode is fast, transparent, and no frames are lost. This mode is
supported on both GE and FE ports.
• 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 50 meters, the device
uses less power to send frames over the cable, thus saving energy. This
mode is only supported on RJ45 GE ports; it does not apply to Combo
ports.
This mode is globally disabled by default. It cannot be enabled if EEE mode
is enabled (see below).
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. See
Ethernet Feature for more information (available on GE models only).
EEE is enabled globally by default. On a given port, if EEE is enabled, short reach
mode be disabled. If Short Reach Mode is enabled, EEE be grayed out.
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.).
On the System Summary page, the LEDs that are displayed on the device board
pictures are not affected by disabling the LEDs.
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.
Cisco 500 Series Stackable Managed Switch Administration Guide
Port Management
Configuring Green Ethernet
802.3az Energy Efficient