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Troubleshoot Pac
ket Forwarding Engine Comp onen ts
Juniper Networks Technical Assistance Center
If you need ass
istance during troubleshooting, you can contact the Juniper Networks Technical
Assistance Center (JTAC) by e-mail or telephone. See “How to Request Support” on page xix.
Troubleshoot the Fan Tray
The fan tray installed along one side of the chassis houses four fans that draw room air into
the chassis to maintain an acceptable operating temperature for the Routing Engine, PICs,
FEB, and othe
r components. For a graphic depiction of the airflow, see Figure 10.
For the fan tray to function properly, the clearance around the chassis must be sufficient for
unobstructe
d airflow. See “Clearance Requirements for Airflow and Hardware Maintenance”
on page 40.
Temperature
sensors on the components detect temperatures above the acceptable range.
Fan failure or an excessive temperature condition triggers the red alarm LED on the craft
interface. If the temperature passes the acceptable maximum, the Routing Engine shuts
down the rou
ter by turning off the power supplies.
To troubleshoot the fan tray, follow these guidelines:
• Check the status of the fans in the fan tray by issuing the show chassis environment
command. The o utput includes an entry for each fan, as shown in this example:
user@host> show chassis environment
Class Item Status Measurement
...
Fans Left Fan 1 OK Spinning at normal speed
Left Fan 2 OK Spinning at normal speed
Left Fan 3 OK S
pinning at normal speed
Left Fan 4 OK Spinning at normal speed
...
For further description of the output from the command, see the JUNOS Internet
Software Ope
rational M ode Command Reference: Protocols, Class of Service, Chassis,
and Management.
• If the fan tra
y fails, determine whether you can distinguish individual blades in a
fan—this is not possible when the fans are rotating at normal speed.
Troubleshoot Packet Forwarding Engine Components
The followi
ng sections describe how to troubleshoot the FEB and PICs:
• Troubleshoot the FEB on page 125
• Troubleshoot PICs on page 125
124 M5 and M10 Internet Routers Hardware Guide