This document is intended to assist in troubleshooting hardware-related issues for Line Cards (LC) on Juniper platforms. It outlines a systematic approach to identifying and resolving problems with LC modules, covering typical symptoms such as the LC not booting up, no response on the console, and various CLI-reported errors including Hard errors, Temperature errors, Volt errors, and other related hardware faults.

• LC not booting OR LC not completing boot cycle OR LC not responding on console

• Hard Errors

• Temp Errors

• Volt Errors

Before starting troubleshooting, ensure the device is receiving proper power and verify the status of all the SYS (System/Chassis) LED’s to be functional.

LC not booting OR LC not completing boot cycle OR LC not responding on

• Console Check: Connect to the RE via console cable and verify if the linecard is showing proper status and not stuck in inactive or down state.
• Power Cycle: Attempt to restart the linecard in case its not active.
• Reseat: Reseat the linecard to ensure proper contact.
• Linecard Isolation: If possible, move the linecard to a different slot/chassis to rule out line chassis connection specific problems.
• Replacement: If the above steps don't resolve the issue, replace the defective MIC/PIC with a spare.

Similarly in case of MIC/PIC Troubleshooting - MIC/PIC not passing traffic OR MIC/PIC not getting detected

• LED: Check the status of each port on a MIC/PIC by looking at the LED located on the MIC faceplate.
• CLI: If MIC/PIC is offline, check the status of a MIC by issuing the show chassis fpc pic-status CLI command.
• Power Cycle: Try cycling the power of the MIC/PIC (offline/online).
• Reseat: Reseat the MIC/PIC card to ensure proper contact.
• Line Card Isolation: If possible, move the MIC/PIC to a different line card to rule out line card specific problems.
• Spare MIC/PIC Testing: If available, connect a spare MIC/PIC to cross-check for hardware failure.
• Replacement: If the above steps don't resolve the issue, replace the defective MIC/PIC with a spare.

Hard Errors

The Hard Errors alarm signifies critical errors detected on the FPC or Linecard, often indicating underlying hardware malfunctions or failures in data processing. These alarms are typically strong indicators of potential hardware issues.

Examples of Hard Errors

root@router> show chassis alarms 
Mar 25 07:51:09
1 alarms currently active
Alarm time    Class Description
2025-01-25 00:00:01 IST
Major FPC X Hard errors

Temp Errors

The "FPC XX Temp Sensor Fail" alarm indicates that there is a failure in the temperature sensor of FPC. This means that the device is unable to accurately measure the temperature of the FPC XX, which is critical for ensuring proper functioning and preventing overheating issues.

Examples of Temp Errors

Juniper@Router> show chassis alarms
--------------------------------------------------------------------------

3 alarms currently active
Alarm time Class Description
XXXX-XX-XX XX:XX:XX +03 Minor FPC XX Temp Sensor Fail

If the Temp Errors persist despite rebooting, re-seating the line cards, and completing all standard troubleshooting steps, an RMA is recommended.

Volt Errors

The "FPC XX Volt Sensor Fail" alarm indicates a failure in the voltage sensor of FPC XX. This means that the device is unable to accurately measure the voltage levels on FPC XX, which are essential for ensuring stable and reliable power supply to the components on the FPC.

Examples of Volt Errors

Juniper@Router> show chassis alarms

--------------------------------------------------------------------------

1 alarms currently active

Alarm time Class Description

XXXX-XX-XX XX:XX:XX +03 Minor FPC XX Volt Sensor Fail

This FPC situation indicates a potential hardware problem, which could be either transient or permanent. Before an RMA can be processed, please perform all standard troubleshooting steps: reseat components, reboot the system, and upgrade software if required.

General Guidelines for LC Troubleshooting

Before proceeding with RMA for the FPC / Linecard, please follow the procedures below:

• Check Related Events Review any related events that occurred at or just before the log message to gather hints on the possible cause of the problem. Also collect the show chassis related commands at the time of the issue.
• Reboot / Reseat the FPC / Linecard and CB
  • Soft Restart: Use the following command to perform a soft restart:
    request chassis fpc slot <slot-number> (offline | online | restart)
  • Soft Restart CB: To restart the CB you could try these commands - request chassis cb slot # offline / online.
  • Reseat – After taking the linecard offline – remove and reinsert the linecard.
• Stabilization
  Wait for the FPC and CB to stabilize before concluding it to be a hardware issue, especially if the FPC/CB or router was recently rebooted.

General Reference KB for Line Card troubleshooting

KB93365 - Troubleshooting Guide: Routing Engine, MIC/PIC, and Line Card Hardware Issues [juniper.net]

For additional assistance from Juniper Support, open a case with all the relevant files such as RSI/Logs, and include the answers to the following questions:

• Has any new equipment been added to the network recently?
• If you recently upgraded or downgraded software, were you seeing issues prior to the upgrade or downgrade?
• Does traffic flow through the device? 
• About how long did the system run before failure?

2025-06-25: Article created