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Lantronix
SM24TBT2DPA and SM24TBT2DPB Web User Guide
2-2 Green Ethernet
Energy Efficient Ethernet (EEE) is a power saving option that reduces the power usage when there is low
or no traffic utilization. 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 on the value of the wakeup time in order to make sure that both the receiving and
transmitting device has all circuits powered up when traffic is transmitted. The devices can exchange
wakeup time information using the LLDP protocol.
EEE works for ports in auto-negotiation mode, where the port is negotiated to either 1G or 100 Mbps full
duplex mode. For ports that are not EEE-capable the corresponding EEE checkboxes are grayed out and
thus impossible to enable EEE.
When a port is powered down for saving power, outgoing traffic is stored in a buffer until the port is
powered up again. Because there is some overhead in turning the port down and up, more power can be
saved if the traffic can be buffered until a large burst of traffic can be transmitted. Buffering traffic will give
some latency in the traffic.
Web Interface
To configure a Port Power Saving Configuration in the web interface:
1. Click Configuration, Green Ethernet, Port Power Savings.
2. At the dropdown, select to optimize EEE for either Latency or Power.
3. Enable or disable the EEE and EEE Urgent Queues for each port.
4. Click the Apply button.
Figure 2-2.1: Port Power Savings Configuration
Parameter descriptions:
Optimize EEE for
: The switch can be set to optimize EEE for either Power (best power saving) or Latency
(least traffic latency).
Port:
The switch port number of the logical port.