Maintaining the M120 Fan Trays

Purpose

For optimum cooling, verify the condition of the fans.

Action

• Monitor the status of the fans. Each fan tray contains multiple fans that work in unison to cool the router components. If one fan fails, the host subsystem adjusts the speed of the remaining fans to maintain proper cooling. A red alarm is triggered when a fan fails, and a yellow alarm is triggered when a fan tray is removed.
• To display the status of the cooling system, issue the show chassis environment command. The output is similar to the following:
  
  

  user@host> show chassis environment

  Class Item                   Status     Measurement
  Temp  PEM 0                  OK
        PEM 1                  OK
        Routing Engine 0       OK         56 degrees C / 132 degrees F
        Routing Engine 1       Absent
        CB 0 Intake            OK         52 degrees C / 125 degrees F
        CB 0 Exhaust A         OK         47 degrees C / 116 degrees F
        CB 0 Exhaust B         OK         44 degrees C / 111 degrees F
        CB 1 Intake            OK         41 degrees C / 105 degrees F
        CB 1 Exhaust A         OK         40 degrees C / 104 degrees F
        CB 1 Exhaust B         OK         42 degrees C / 107 degrees F
        FEB 2 Intake           OK         44 degrees C / 111 degrees F
        FEB 2 Exhaust A        OK         44 degrees C / 111 degrees F
        FEB 2 Exhaust B        OK         48 degrees C / 118 degrees F
        FEB 3 Intake           OK         46 degrees C / 114 degrees F
        FEB 3 Exhaust A        OK         46 degrees C / 114 degrees F
        FEB 3 Exhaust B        OK         52 degrees C / 125 degrees F
        FEB 4 Intake           OK         45 degrees C / 113 degrees F
        FEB 4 Exhaust A        OK         46 degrees C / 114 degrees F
        FEB 4 Exhaust B        OK         49 degrees C / 120 degrees F
        FEB 5 Intake           OK         42 degrees C / 107 degrees F
        FEB 5 Exhaust A        OK         41 degrees C / 105 degrees F
        FEB 5 Exhaust B        OK         53 degrees C / 127 degrees F
        FPC 2 Exhaust A        OK         39 degrees C / 102 degrees F
        FPC 2 Exhaust B        OK         40 degrees C / 104 degrees F
        FPC 3 Exhaust A        OK         41 degrees C / 105 degrees F
        FPC 3 Exhaust B        OK         42 degrees C / 107 degrees F
        FPC 4 Exhaust A        OK         43 degrees C / 109 degrees F
        FPC 4 Exhaust B        OK         41 degrees C / 105 degrees F
        FPC 5 Exhaust A        OK         39 degrees C / 102 degrees F
        FPC 5 Exhaust B        OK         39 degrees C / 102 degrees F
  Fans  Front Top Tray Fan 1   OK         Spinning at high speed
        Front Top Tray Fan 2   OK         Spinning at high speed
        Front Top Tray Fan 3   OK         Spinning at high speed
        Front Top Tray Fan 4   OK         Spinning at high speed
        Front Top Tray Fan 5   OK         Spinning at high speed
        Front Top Tray Fan 6   OK         Spinning at high speed
        Front Top Tray Fan 7   OK         Spinning at high speed
        Front Top Tray Fan 8   OK         Spinning at high speed
        Front Bottom Tray Fan 1 OK        Spinning at high speed
        Front Bottom Tray Fan 2 OK        Spinning at high speed
        Front Bottom Tray Fan 3 OK        Spinning at high speed
        Front Bottom Tray Fan 4 OK        Spinning at high speed
        Front Bottom Tray Fan 5 OK        Spinning at high speed
        Front Bottom Tray Fan 6 OK        Spinning at high speed
        Front Bottom Tray Fan 7 OK        Spinning at high speed
        Front Bottom Tray Fan 8 OK        Spinning at high speed
        Rear Top Tray Fan 1    OK         Spinning at high speed
        Rear Top Tray Fan 2    OK         Spinning at high speed
        Rear Top Tray Fan 3    OK         Spinning at high speed
        Rear Top Tray Fan 4    OK         Spinning at high speed
        Rear Top Tray Fan 5    OK         Spinning at high speed
        Rear Top Tray Fan 6    OK         Spinning at high speed
        Rear Top Tray Fan 7    OK         Spinning at high speed
        Rear Top Tray Fan 8    OK         Spinning at high speed
        Rear Bottom Tray Fan 1 OK         Spinning at high speed
        Rear Bottom Tray Fan 2 OK         Spinning at high speed
        Rear Bottom Tray Fan 3 OK         Spinning at high speed
        Rear Bottom Tray Fan 4 OK         Spinning at high speed
        Rear Bottom Tray Fan 5 OK         Spinning at high speed
        Rear Bottom Tray Fan 6 OK         Spinning at high speed
        Rear Bottom Tray Fan 7 OK         Spinning at high speed
        Rear Bottom Tray Fan 8 OK         Spinning at high speed

Note: The fan numbers are stamped into the fan tray sheet metal next to each fan.