MIB: CISCO-ENTITY-FRU-CONTROL-MIB.
The object name: `cefcFanTrayOperStatus`.
The operational state of the fan or a fan tray.
Possible values:
-  unknown (1) - unknown;
-  up (2) - powered on;
-  down (3) - powered down;
-  warning (4) - partial failure; needs replacement as soon as possible.