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1.7 EEE
The section allows the user to inspect and configure the current EEE port settings.
EEE is a power saving option that reduces power usage when there is very low traffic
utilization (or no traffic).
EEE works by powering down circuits when there is no traffic. When a port gets data
to be transmitted, all circuits are powered up. The time it takes to power up the
circuits is called wakeup time. The default wakeup time is 17 us for 1Gbit links and
30 us 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 wakeup time using the LLDP protocol.
To maximize power saving, the circuit doesn’t start once the transmit data is ready
for a port. Instead, it’s queued until 3000 bytes of data are ready to be transmitted.
To avoid a large delay in case there is data less than 3000 bytes waiting to be
transmitted, data are always transmitted after 48 us, giving a maximum latency of 48
us + the wakeup time.
If desired, it is possible to minimize the latency for specific frames, by mapping the
frames to a specific queue through QOS, and then mark the queue as an urgent
queue. When an urgent queue gets data ready to be transmitted, the circuits will be
powered up at once and the latency will be reduced to the wakeup time.
Web Interface
To configure the EEE Configuration in the web interface:
1.
Click Configuration, Port, and then EEE.
2.
To evoke which port you want to enable the EEE function.
3.
To evoke which “EEE Urgent Queues” level, ranging from 1 to 8. The queue
will postpone the transmission until 3000 bytes of data are ready to be
transmitted.
4.
Click “Save” to save the setting.
5.
If you want to cancel the setting, click the reset button to revert back to
previously saved values.
Figure 3-1.7: The EEE Configuration
