BFD reports a LAG as down even when healthy links are still available

Symptom

NOTE:

BFD is not supported on the 6100 and 6200 Switch Series.

The Bidirectional Forward Detection (BFD) feature reports a Link Aggregation (LAG), as being down, even though there are healthy LAG links available. The LAG, containing the downed link, will eventually rebalance the traffic to its other links.

Cause

This notification occurs when the minimum BFD control packet reception interval is set at a faster rate than the Link Aggregation Control Protocol (LACP) rate and LAG rebalancing occurs. BFD assumes that the link is down without realizing that the LAG is rebalancing the traffic load.

Action

  1. Set the minimum BFD control packet reception interval to a slower rate than the LACP rate or set the LACP rate to a faster rate than the minimum BFD control packet reception interval.

    1. To find the current settings of the minimum BFD control packet reception interval, enter the show running-config command.

      The minimum BFD control packet reception interval setting is listed as bfd min-receive-interval in the command output and the measurement is in ms.

    2. To find the current rate of LACP, enter the show lacp aggregates command.

      The LACP rate is listed as the Heatbeat rate in the command output.

    3. To change the minimum BFD control packet reception interval, enter the bfd min-receive-interval command.

    4. To change the LACP rate, enter the lacp rate {fast | slow} command.