An NE40E and a UMG were connected. After process-interface-status was issued to enable status change of the BFD session to be triggered by status change of the interface to which the session was bound, BGF session flapped at peak hours every day.
Huawei completed the following steps to diagnose the problem:
1. Check the BFD session flap log BFD/4/STACHG_TODWN.
According to the Diagnostic parameter, the flap type was DetectDown, meaning that BFD packets were not received as expected during the BFD session detection period on the NE40E (BFD down).
2. Checked BFD table entries on the NE40E. The cable entries indicated no exception. BFD for interface did not re-deliver table entries upon Layer 3 protocol status changes.
3. Checked whether traffic volume was large.
Typically, a BFD flap does not last long and is likely to occur if traffic is heavy. The NE40E transmitted BFD packets using its logic chip. No congestion was found at the interface.