C
HAPTER
4
| Configuring the Switch
Configuring Power Reduction
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REDUCING POWER TO
IDLE QUEUE CIRCUITS
Use the EEE Configuration page to configure Energy Efficient Ethernet
(EEE) for specified queues, and to specify urgent queues which are to
transmit data after maximum latency expires regardless of queue length.
PATH
Configuration, Power Reduction, EEE
COMMAND USAGE
â—† EEE works by powering down circuits when there is no traffic. When a
port gets data to be transmitted all relevant circuits are powered up.
The time it takes to power up the circuits is call the wakeup time. The
default wakeup time is 17 µs for 1 Gbps links and 30 µs for other link
speeds. EEE devices must agree upon the value of the wakeup time in
order to make sure that both the receiving and transmitting devices
have all circuits powered up when traffic is transmitted. The devices
can exchange information about the device wakeup time using LLDP
protocol.
To maximize power savings, the circuit is not started as soon as data is
ready to be transmitted from a port, but instead waits until 3000 bytes
of data is queued at the port. To avoid introducing a large delay when
the queued data is less then 3000 bytes, data is always transmitted
after 48 µs, giving a maximum latency of 48 µs plus the wakeup time.
â—† If required, it is possible to minimize the latency for specific frames by
mapping the frames to a specific queue (EEE Urgent Queues). When an
urgent queue gets data to be transmitted, the circuits will be powered
up at once and the latency will be reduced to the wakeup time.
PARAMETERS
These parameters are displayed:
◆ Port – Port identifier.
◆ EEE Enabled – Enables or disables EEE for the specified port.
◆ EEE Urgent Queues – Specifies which are to transmit data after the
maximum latency expires regardless queue length.
WEB INTERFACE
To configure the power reduction for idle queue circuits:
1. Click Configuration, Power Reduction, EEE.
2. Select the circuits which will use EEE.
3. If required, also specify urgent queues which will be powered up once
data is queued and the default wakeup time has passed.
4. Click Save.
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