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Syslog message: MQSS.*FO.*Parity error detected for output buffer control



Article ID: KB32085 KB Last Updated: 12 Oct 2021Version: 2.0

The "Parity error detected for output buffer control" message reports a transient hardware error in EACHIP Fabric output block.

This is a Troubleshooting Article for a PFE ASIC Syslog Event.
To view other documented syslog events related to XMCHIP, XLCHIP, MQCHIP, LUCHIP, EACHIP, and PECHIP, see KB31893 - Index of Articles for Troubleshooting PFE ASIC Syslog Events.



When a "Parity error detected for output buffer control" event occurs, a message similar to the following is reported:

Apr 25 16:19:22 router-0 fpc7 MQSS(0):MQSS(0): FO: Parity Protect: Parity error detected for output buffer control


  • No operational impact if the event is not reported repeatedly

  • Alarm will be raised



This is due to a transient hardware issue within the EACHIP Fabric output block.


Perform these steps to determine the cause and resolve the problem (if any).  Continue through each step until the problem is resolved.

  1. Collect the show command output.

    Capture the output to a file (in case you have to open a technical support case). To do this, configure each SSH client/terminal emulator to log your session.

    show log messages
    show log chassisd
    start shell network pfe <fpc#>
    show nvram
    show syslog messages

  2. Analyze the show command output.

    In the 'show log messages', review the events that occurred at or just before the appearance of the "Parity error detected for output buffer control" message. Frequently these events help identify the cause.

  • No RMA is required

  • With the single occurrence, the alarm can be cleared using command:
    • ‚Äčclear chassis fpc errors fpc-slot <x> all

    • ‚ÄčNote: This command is available in Junos OS 16.1R4-S2, 16.1R5, 16.2R2, 17.1R2, and 17.2R1 or higher. 

  • Contact your technical support representative if this event is seen repeatedly.

This article is indexed in KB31893 - Primary Index of Articles for Troubleshooting PFE ASIC Syslog Events; tag EACHIPTSG

Tip: When looking at an event in the logs, it is important to focus on the first error message in a collection of syslog messages. The first error message is usually the cause of all the follow-on error messages. The follow-on collateral damage error messages can be ignored.

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