On QFX series switch, no alarm would be raised even though inserted PSU or FAN module which has a different airflow. This is unexpected and a software bug.

This KB describes the issue details and share the potential PRs that have the fix.

On QFX series switch, no alarm would be raised even if inserted power supply or FAN module with different airflow.

Here is the sample output in case of PSU:

Power Supply 0   REV 04   740-041741   1GA27332679       JPSU-650W-AC-AFO
Power Supply 1   REV 04   740-044332   1GA15367420       JPSU-650W-AC-AFI   <<<= Airflow mismatch

root> show chassis alarms
No alarms currently active <==================================================== No airflow errors

Expected output is the following:

root> show chassis alarms no-forwarding

1 alarms currently active
Alarm time               Class  Description
2023-04-26 04:10:08 PDT  Major  FPC0: PEM: Airflow Direction Mismatch

Here is the sample output in case of FAN:

Fan Tray 0 QFX5120-32C Fan Tray 0, Front to Back Airflow - AFO <================ Airflow mismatch
Fan Tray 1 QFX5120-32C Fan Tray 1, Back to Front Airflow - AFI
Fan Tray 2 QFX5120-32C Fan Tray 2, Back to Front Airflow - AFI
Fan Tray 3 QFX5120-32C Fan Tray 3, Back to Front Airflow - AFI
Fan Tray 4 QFX5120-32C Fan Tray 4, Back to Front Airflow - AFI
Fan Tray 5 QFX5120-32C Fan Tray 5, Back to Front Airflow - AFI

root> show chassis alarms
No alarms currently active <==================================================== No airflow errors

Expected output is the following:

root> show chassis alarms no-forwarding

1 alarms currently active
Alarm time               Class  Description
2023-04-18 10:19:38 IST  Major  FPC 0 Fan Airflow direction mismatch