Juniper M7I Hardware Manual page 109

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Copyright © 2010, Juniper Networks, Inc.
During normal operation, the fans in the fan tray function at less than full speed. The
router constantly monitors the temperatures detected by sensors on the router
components, adjusting the speed of the fans as necessary. If the router temperature
exceeds the acceptable maximum, the router turns off the power supplies.
The following conditions automatically cause the fans to run at full speed and trigger
the indicated alarm:
A fan fails (red alarm).
The router temperature exceeds the "temperature warm" threshold (yellow alarm).
The temperature of the router exceeds the maximum ("temperature hot") threshold
(red alarm and automatic shutdown of the power supplies).
For more information about cooling-related alarms, see "Hardware and Interface Alarm
Messages" on page 76.
To troubleshoot the fans:
If the red alarm LED on the craft interface lights, use the
to determine the source of the problem. The display reports the number of alarm
conditions and the source of each alarm. For a list of messages, see "Hardware and
Interface Alarm Messages" on page 76.
Issue the show chassis alarms
alarm condition.
If both power supplies have failed, the system temperature might have exceeded the
threshold, causing the system to shut down. See "Troubleshooting the M7i Power
System When the LEDs on All M7i Power Supplies Are Blinking or Off" on page 81.
If the fan tray has failed, it must be replaced for the router to operate normally. For
replacement instructions, see "Replacing the M7i Fan Tray" on page 117. For instructions
about returning a faulty component to Juniper Networks, see "Contacting Customer
Support" on page 191.
M7i Power System Description on page 21
M7i Router Power Requirements on page 163
Maintaining the M7i Power Supplies on page 72
Powering on the M7i Router on page 59
Chapter 14: Troubleshooting M7i Hardware Components
show chassis alarms
command for more information about the source of an
command
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