Technical Information
4–13
4.3.6
Fan Assembly
The fan assembly provides the air flow used to cool the bridge. The assembly con-
tains two fans and is located on the left side of the card cage. A circuit on the AP2
module monitors the rotation of the fans and sets a fan failure bit (in the AP2 module)
whenever the fan is rotating too slowly or not at all. Both the self-test diagnostics and
the operational firmware periodically check the status of the fans by reading this bit.
If the diagnostics detect a fan failure:
•
The FAN_BAD indicator remains on after the lamp check is complete.
•
If the diagnostics detect no fatal error (note that fan failure is not a fatal er-
ror), the operational firmware is invoked after self-test is complete.
•
If the diagnostics detect a fatal error, the bridge is powered down after 2 min-
utes.
If the operational firmware detects a fan failure:
•
The FAN_BAD indicator turns on.
•
A management status bit is set to indicate the fan failure.
•
After 5 minutes, the bridge is powered down.
