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Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SG
OL-25340-01
Chapter 12 Environmental Monitoring and Power Management
IEEE 802.3az Energy Efficient Ethernet
Energy Efficient Ethernet is an extension of the IEEE 802.3 standard that provides a mechanism and a
standard for reducing energy usage without reducing the vital function of network interfaces. EEE
defines the signaling necessary for energy savings during periods where no data is sent on the interface.
EEE defines support for physical layer devices (PHYs) to operate in Low Power Idle (LPI) mode. When
enabled, EEE supports QUIET times during low link utilization allowing both sides of a link to disable
portions of each PHY's operating circuitry and save power. This functionality is provided per port and
is not enabled by default. To avoid issues with EEE functionality on any port during run-time, Cisco
provides the power efficient-ethernet auto command to enable or disable EEE.
Because EEE relies on Auto Negotiation pulse to determine whether to activate EEE, the port must
initially enable auto negotiation. Furthermore, EEE is the correct action provided the speed is auto
100M, auto 1000M, or auto 100M and 1000M. 10M (either auto or forced mode) does not require EEE
for power saving.
For more details, see the URL:
http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps4324/white_paper_c11-676336.pdf
Sections include:
• Determining EEE Capability, page 12-21
• Enabling EEE, page 12-21
• Determining EEE Status, page 12-22
Determining EEE Capability
To determine whether a line card supports EEE, use the show interface capabilities module module
command, as follows:
Switch# show interface capabilities module 3
GigabitEthernet3/1
Model: WS-X4748-NGPOE+E-RJ-45
Type: 10/100/1000-TX
Speed: 10,100,1000,auto
Duplex: half,full,auto
Auto-MDIX: yes
EEE: yes ( 100-Tx and 1000-T auto mode )
Enabling EEE
To enable EEE on a given port, use the power efficient-ethernet auto command.
The following example shows how to enable EEE:
Switch# config t
Command Purpose
Step 1
Switch# configure terminal Enters configuration mode.
Step 2
Switch(config)# interface interface
Enters interface configuration mode and
specifies the port to be configured.
Step 3
Switch(config-if)# power efficient-ethernet auto
Enables EEE.
Step 4
Switch(config-if)# exit Exits global configuration mode.
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