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[MX/PTX] FPC undetected after routing-engine primary role switchover



Article ID: KB36798 KB Last Updated: 27 Apr 2021Version: 1.0

This article provides troubleshooting steps when one or more FPCs are undetected only after RE (routing engine) primary role switchover.

  • FPC undetected, showing as empty when checked using 'show chassis fpc' command
  • Core files seen for chassisd process

Detecting any FRU is the job of chassisd using the i2c utility. The FPC connects to the primary RE after it is detected by the chassisd process.

The Control Board houses the internal Broadcom switch that connects the primary, back-up RE, and the PFEs. The CB slot primary role is dependent on the RE primary role, which means if RE0 is the primary RE, CB 0 is the primary CB . With RE1 as primary RE, CB 1 becomes the primary CB.

In some cases, on doing a RE switchover, some FPCs are seen undetected. On running the 'show chassis hardware', the FPC module is not seen. On running 'show chassis fp', the status is empty for the FPC slot.

This is due to an underlying hardware issue with the CB that is the current primary. It can be a case of bend pins or slot damage with the CB. Please validate by switching primary role to the other RE, to confirm that the corresponding CB is able to detect the FPC. In case there is a spare CB available on the chassis (for example, on MX 960 ), swap the affected CB with a working one and validate as well.


Once the fault is isolated to the CB, please contact your JTAC Representative to get it validated and the CB replaced.

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