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. 找到当前设置的最低BFD有限公司ntrol packet reception interval, enter theshow running-configcommand.

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

    2. To find the current rate of LACP, enter theshow lacp aggregatescommand.

      The LACP rate is listed as theHeatbeat ratein the command output.

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

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