Description

This article explains the meaning of the syslog message, 'FPC 0 Airflow direction of PSU and Chassis fan are not matching' on EX series devices.

Symptoms

Active alarm:

user@host> show chassis alarms no-forwarding
1 alarms currently active
Alarm time               Class  Description
2019-07-11 15:06:25 UTC  Major  FPC 0 Airflow direction of PSU and Chassis fan are not matching 

Syslog Message:

Sep 13 06:57:48  send: red alarm set, device FPC 0, reason FPC 0 Airflow direction of PSU and Chassis fan are not matching
Sep 13 07:11:13  fpc 0: new port map received pic slot 0​

Example Hardware Inventory:

user@host> show chassis hardware
Sep 11 11:10:21
Hardware inventory:
Item             Version  Part number  Serial number     Description
Chassis                                XXXXXXXXXXXX      EX4550-32F
 
Power Supply 0   REV 03   740-038949   XXXXXXXXXXX       JPSU-650W-DC-AFI  <-- Both Power supplies are of different airflow direction type (AFI and AFO)
Power Supply 1   REV 04   740-043886   XXXXXXXXXXX       JPSU-650W-DC-AFO
Fan Tray                                                 Fan Module, Airflow In (AFI)

OR

user@host> show chassis hardware
Sep 11 11:10:21
Hardware inventory:
Item             Version  Part number  Serial number     Description
Chassis                                XXXXXXXXXXXX      EX4550-32F
 
Power Supply 0   REV 03   740-038949   XXXXXXXXXXX       JPSU-650W-DC-AF0                       
Power Supply 1   REV 04   740-043886   XXXXXXXXXXX       JPSU-650W-DC-AFO
Fan Tray                                                 Fan Module, Airflow In (AFI) <-- Power Supplies are AFO type and Fan Module is AFI type


AFI means Air Flow In (Back to Front Airflow movement) and AFO means Air Flow Out (Front to Back Airflow movement). AFI is also called Reverse Airflow and AFO is called Forward Airflow. See below for example output:

Power Supply 0 REV 01   740-043832   Exx      PS 1000W AC REVERSE AIR FLOW CONTROL
Power Supply 1 REV 01   740-044237   Exx     PS 1000W AC  FORWARD AIR FLOW CONTROL


Example Chassis Environment:

user@host> show chassis environment      
Sep 11 10:48:34
Class Item                           Status     Measurement
Power FPC 0 Power Supply 0           OK       
      FPC 0 Power Supply 0 Airflow   OK         Back to front   <-- Mismatch
      FPC 0 Power Supply 1           OK       
      FPC 0 Power Supply 1 Airflow   OK         Front to back  <-- Mismatch

Temp  FPC 0 CPU                      OK         27 degrees C / 80 degrees F
      FPC 0 GEPHY Front Left         OK         37 degrees C / 98 degrees F
      FPC 0 GEPHY Front Middle       OK         45 degrees C / 113 degrees F
      FPC 0 GEPHY Front Right        OK         44 degrees C / 111 degrees F
      FPC 0 EX-PFE1                  OK         41 degrees C / 105 degrees F
      FPC 0 Rear Left PCB            OK         27 degrees C / 80 degrees F
      FPC 0 Rear Middle PCB          OK         37 degrees C / 98 degrees F
      FPC 0 Rear Right PCB           OK         32 degrees C / 89 degrees F
      FPC 0 PIC1                     OK         46 degrees C / 114 degrees F
      FPC 0 PIC2                     OK         37 degrees C / 98 degrees F
      FPC 0 Local Sensor             OK         26 degrees C / 78 degrees F
Fans  FPC 0 Fan 1                    OK         Spinning at normal speed
      FPC 0 Fan 2                    OK         Spinning at normal speed
      FPC 0 Fan 3                    OK         Spinning at normal speed
      FPC 0 Fan 1 Airflow            OK         Airflow In (AFI) <-- Indicates Back to Front Air Movement
      FPC 0 Fan 2 Airflow            OK         Airflow In (AFI)
      FPC 0 Fan 3 Airflow            OK         Airflow In (AFI)

Solution

  1. PSUs do not match the same airflow as Fans
  2. A difference in airflow direction between the PSUs

Ideally, a system cannot have AFI and AFO components installed together to work as one whole unit. When PSUs are mixed up or when the PSU type does not match the chassis type, then this issue will occur. In that case, make sure you install the right kind of PSU/ Fans into the slots of a chassis. 

If a chassis has all the correct types of PSUs and Fan Trays but you still see the error, then contact JTAC for further analysis.