5.13.4 Monitor LLDP EEE

By using EEE, power savings can be achieved at the expense of traffic latency. This latency occurs due to the circuits EEE turns off to save power and time needed to boot up before sending traffic over the link. This time is called wakeup time. To achieve minimal latency, devices can use LLDP to exchange information about their respective tx and rx wakeup time, to agree upon the minimum wakeup time they need.

If the interface does not support EEE, then it displays as EEE not supported for this interface. If EEE is not enabled on a particular interface, then it displays as EEE not enabled for this interface. If the link partner does not support EEE, then it displays as Link partner is not EEE capable.

Figure 5-56. LLDP Neighbors EEE Information

The LLDP Neighbors EEE Information page has the following parameters:

  • Local Interface: The interface at 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
  • RxTw: 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 Received Tw: The link partner's fallback receives Tw. A receiving link partner may inform the transmitter of an alternate desired Tw_sys_tx. As a receiving link partner might 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 are 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 if 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 partner's 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 through 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 through 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