EEE

By using EEE power savings can be achieved at the expense of traffic latency. This latency occurs due to that the circuits EEE turn off to save power, need time to boot up before sending traffic over the link. This time is called “wakeup time.” To achieve minimal latency, devices can use LLDP (Link Layer Discovery Protocol) to exchange information about their respective tx and rx “wakeup time,” as a way to agree upon the minimum wakeup time they need.

This page provides an overview of EEE information exchanged by LLDP.

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Object Description
Local Port The port on which LLDP frames are received or transmitted.
Tx Tw The link partner's maximum time that transmit path can hold-off sending data after deassertion of LPI.
Rx Tw The link partner's time that receiver would like the transmitter to hold-off to allow time for the receiver to wake from sleep.
Fallback Receive Tw The link partner's fallback receive Tw.

A receiving link partner may inform the transmitter of an alternate desired Tw_sys_tx. Since a receiving link partner is likely to have discrete levels for savings, this provides the transmitter with additional information that it may use for a more efficient allocation. Systems that do not implement this option default the value to be the same as that of the Receive Tw_sys_tx.

Echo Tx Tw The link partner's Echo Tx Tw value.

The respective echo values shall be defined as the local link partners reflection (echo) of the remote link partners respective values. When a local link partner receives its echoed values from the remote link partner it can determine whether or not the remote link partner has received, registered and processed its most recent values. For example, if the local link partner receives echoed parameters that do not match the values in its local MIB, then the local link partner infers that the remote link partners request was based on stale information.

Echo Rx Tw The link partner's Echo Rx Tw value.
Resolved Tx Tw The resolved Tx Tw for this link.
Note: NOT the link partner

The resolved value that is the actual “tx wakeup time “ used for this link (based on EEE information exchanged via LLDP).

Resolved Rx Tw The resolved Rx Tw for this link.
Note: NOT the link partner

The resolved value that is the actual “tx wakeup time “ used for this link (based on EEE information exchanged via LLDP).

EEE in Sync Shows whether the switch and the link partner have agreed on wake times.
  • Red - Switch and link partner have not agreed on wakeup times.
  • Green - Switch and link partner have agreed on wakeup times.
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