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Troubleshooting the T4000 Cooling System

 

Problem:

Description:

The following alarms, LEDs, and other conditions indicate a problem with the cooling system:

  • A red alarm indicates that the temperature of the router exceeds the maximum (“temperature hot”) threshold.

  • Automatic shutdown of the power supplies can be caused by the temperature of the router exceeding the maximum (“temperature hot”) threshold. The control board turns off the power supplies because the router temperature exceeds the acceptable maximum.

  • A red alarm indicates that a fan failed.

  • A yellow alarm indicates that the router temperature exceeds the “temperature warm” threshold.

  • A yellow alarm indicates that one of the fan trays was removed.

  • One or more fans in a fan tray function at full speed. The control boards constantly monitor the temperatures detected by sensors on the midplane and router components, adjusting the speed of the fans as necessary. If one fan fails, the host subsystem adjusts the speed of the remaining fans to maintain proper cooling.

Table 1: T4000 Cooling System Fan Tray Alarms

Alarm Type

LCD Message

CLI Message

Alarm Condition

Solution

Red

Fan Failure

fan-name Failure

A fan has failed.

Replace the fan tray.

Fans Missing

Too many fans missing or failing

A fan tray is missing or too many fan trays have failed.

Reinstall the fan tray in the chassis.

<fan-name> Improper

<fan-name> Improper for Platform

A fan tray is unsupported for the T4000 router.

Replace with an appropriate fan tray. For a list of supported fan trays, see T4000 Cooling System Description.

Incompatible rear fan tray or front fan tray detected

An incompatible fan tray is inserted into the chassis.

Replace with an appropriate fan tray.

Yellow

Fan Removed

fan-name Removed

A fan tray has been removed.

Reinstall the fan tray in the chassis.

Table 2: T4000 Temperature Alarms

Alarm Type

Craft Interface LCD Message

CLI Message

Alarm Condition

Solution

Red

Temperature Hot

Temperature Hot

The chassis temperature exceeded the recommend hot temperature threshold. If this condition persists, the router shuts down.

  • Place your hand near the exhaust vents at the rear of the chassis to determine whether the fans are pushing air out of the chassis.

    Verify that the room temperature is within acceptable limits.

  • Verify that there is sufficient air flow.

  • Verify that the cooling system in the chassis is operating properly.

Sensor Failure

Temperature sensor failure

A temperature sensor failed.

Contact JTAC.

Yellow

Temperature Warm

Temperature Warm

The chassis temperature exceeded the recommended warm temperature threshold.

  • Place your hand near the exhaust vents at the rear of the chassis to determine whether the fans are pushing air out of the chassis.

  • Verify that the room temperature is within acceptable limits.

  • Verify that there is sufficient air flow.

  • Verify that the cooling system in the chassis is operating properly.

Solution

To troubleshoot the cooling system:

  1. Check the red and yellow alarm LEDs on the craft interface.
  2. Find the source of the problem by looking at the craft interface display. The number of alarm conditions, as well as the source of each alarm, appears on the screen. If the craft interface display lists only one fan failure and the other fans are functioning normally, the fan is probably faulty and you need to replace the fan tray.
  3. Use the show chassis alarms command to get information about the source of an alarm condition:
    user@host> show chassis alarms

    For information about the alarms, see Table 1 and Table 2.

  4. Use the show chassis fan command to verify that the status of each fan is OK and that the output display indicates that each of the fans are Spinning at normal speed.
    user@host> show chassis fan

    The fans in the fan trays are listed as follows:

    • Upper front fan tray—Top Left and Top Right

    • Lower front fan tray—Bottom Left and Bottom Right

    • Rear fan tray—Rear

  5. Use the show chassis environment command to check the status and speed of the fans.
    user@host> show chassis environment

    Top Left and Top Right refer to fans in the upper front fan tray. Bottom Left and Bottom Right refer to fans in the lower front fan tray. Rear refers to the fans in the rear fan tray.