Troubleshooting Temperature Alarms in EX Series Switches

 

Problem

Description: EX Series switches generate a temperature alarm FPC 0 EX-PFE1 Temp Too Hot.

Cause

Temperature sensors in the chassis monitor the temperature of the chassis. The switch raises an alarm if a fan fails or if the temperature of the chassis exceeds permissible levels.

Solution

When the switch raises a temperature alarm such as the FPC 0 EX-PFE1 Temp Too Hot alarm, use the show chassis environment and the show chassis temperature-thresholds commands to identify the condition that triggered the alarm.

Caution

To prevent the switch from overheating, do not operate it in an area that exceeds the maximum recommended ambient temperature. To prevent airflow restriction, allow at least 6 inches (15.2 cm) of clearance around the ventilation openings.

  1. Connect to the switch by using Telnet and issue the show chassis environment command. This command displays environmental information about the switch chassis, including the temperature, and information about the fans, power supplies, and Routing Engines. Following is a sample output on an EX9208 switch. The output is similar on other EX Series switches.

    show chassis environment (EX9208 Switch)

    user@switch> show chassis environment

    Table 1 lists the output fields for the show chassis environment command. Output fields are listed in the approximate order in which they appear.

    Table 1: show chassis environment Output Fields

    Field Name

    Field Description

    Class

    Information about the category or class of chassis component:

    • Temp: Temperature of air flowing through the chassis in degrees Celsius (°C) and degrees Fahrenheit (°F).

    • Fans: Information about the status of fans and blowers.

    Item

    Information about the chassis components: Flexible PIC Concentrators (FPCs)–that is, the line cards–, Control Boards (CBs), Routing Engines (REs), Power Entry Modules (PEMs)–that is, the power supplies.

    Status

    Status of the specified chassis component. For example, if Class is Fans, the fan status can be:

    • OK: The fans are operational.

    • Testing: The fans are being tested during initial power-on.

    • Failed: The fans have failed or the fans are not spinning.

    • Absent: The fan tray is not installed.

    Measurement

    Depends on the Class. For example, if Class is Temp, indicates the temperature in degrees Celsius (°C) and degrees Fahrenheit (°F). If the Class is Fans, indicates actual fan RPM.

  2. Issue the command show chassis temperature-thresholds. This command displays the chassis temperature threshold settings. Following is a sample output on an EX9208 switch. The output is similar on other EX Series switches.

    show chassis temperature-thresholds (EX9208 Switch)

    user@ host> show chassis temperature-thresholds

    Table 2 lists the output fields for the show chassis temperature-thresholds command. Output fields are listed in the approximate order in which they appear.

    Table 2: show chassis temperature-thresholds Output Fields

    Field name

    Field Description

    Item

    Chassis component. You can configure for the threshold information for components such as the chassis, the Routing Engines, and FPC for each slot in each FRU to display in the output. By default, information is displayed only for the chassis and the Routing Engines.

    Fan speed

    Temperature thresholds, in degrees Celsius, for the fans to operate at normal and at high speed.

    • Normal—The temperature threshold at which the fans operate at normal speed and when all the fans are present and functioning normally.

    • High—The temperature threshold at which the fans operate at high speed or when a fan has failed or is missing.

    Note: An alarm is not triggered until the temperature exceeds the threshold settings for a yellow alarm or a red alarm.

    Yellow alarm

    Temperature threshold, in degrees Celsius, that trigger a yellow alarm.

    • Normal—The temperature threshold that must be exceeded on the component to trigger a yellow alarm when the fans are running at full speed.

    • Bad fan—The temperature threshold that must be exceeded on the component to trigger a yellow alarm when one or more fans have failed or are missing.

    Red alarm

    Temperature threshold, in degrees Celsius, that trigger a red alarm.

    • Normal—The temperature threshold that must be exceeded on the component to trigger a red alarm when the fans are running at full speed.

    • Bad fan—The temperature threshold that must be exceeded on the component to trigger a red alarm when one or more fans have failed or are missing.

    Fire Shutdown

    Temperature threshold, in degrees Celsius, for the switch to shut down.

When a temperature alarm is triggered, you can identify the condition that triggered it by running the show chassis environment command to display the chassis temperature values for each component and comparing those with the temperature threshold values, which you can display by running the show chassis temperature-thresholds command.

For example, for FPC 3:

  • If the temperature of FPC 3 exceeds 55° C, the output indicates that the fans are operating at a high speed (no alarm is triggered).

  • If the temperature of FPC 3 exceeds 65° C, a yellow alarm is triggered to indicate that one or more fans have failed.

  • If the temperature of FPC 3 exceeds 75° C, a yellow alarm is triggered to indicate that the temperature threshold limit is exceeded.

  • If the temperature of FPC 3 exceeds 80° C, a red alarm is triggered to indicate that one or more fans have failed.

  • If the temperature of FPC 3 exceeds 105° C, a red alarm is triggered to indicate that the temperature threshold limit is exceeded.

  • If the temperature of FPC 3 exceeds 110° C, the switch is powered off.

Table 3 lists the possible causes for the switch to generate a temperature alarm and the respective remedies.

Table 3: Causes and Remedies for Temperature Alarms

Cause

Remedy

Ambient temperature is above threshold temperature.

Ensure that the ambient temperature is within the threshold temperature limit. See Environmental Requirements and Specifications for EX Series Switches.

Fan module or fan tray has failed.

  • Check the fan.

  • Replace the faulty fan module or fan tray.

  • If the above two checks show no problems, open a support case using the Case Manager link at https://www.juniper.net/support/ or call 1-888-314-5822 (toll-free within the United States and Canada) or 1-408-745-9500 (from outside the United States).

Restricted airflow through the switch due to insufficient clearance around the installed switch.

Ensure that there is sufficient clearance around the installed switch. See the following topics to understand the clearance requirements of various EX Series switches.