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Syslog message: MQSS.*BCMW ICM.*Invalid cell sequence.*Packet start without SOP or 16K packet bytes without SOP

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Article ID: KB32084 KB Last Updated: 12 Oct 2021Version: 3.0
Summary:

The "Invalid cell Sequence start without SOP" message reports a software issue in the EACHIP when packets larger than 16K bytes are being processed.

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.

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Symptoms:

When an "Invalid cell Sequence start without SOP" event occurs, a message similar to the following is reported:

Jul 11 13:24:57.586 router0 fpc0 Cmerror Op Set: MQSS(0): MQSS(0): BCMW ICM: Invalid cell sequence (Back-to-back SOP, Packet start without SOP or 16K packet bytes without SOP)

Indications:

  • Permanent impact of packet forwarding in the PFE forwarding will be seen

  • Alarm will be raised

 

Cause:

This is due to a software issue or transient hardware issue within the EACHIP. One possible cause may be the dynamic tunnel interface application defect adding tunnel headers during route forwarding lookup loop until it reaches the 16k limit.

Solution:



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
    exit

  2. Analyze the show command output.

    In the 'show log messages', review the events that occurred at or just before the appearance of the "Invalid cell Sequence start without SOP" message. Frequently these events help identify the cause.

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.

 

Modification History:

Note: KB Team - All changes to this article must be approved by the AI-Scripts Review team (pvs-scripts-review@juniper.net) before re-publishing.


AI-Scripts history:       (Updated by AI-Scripts team only)
 
Date KB Article Version AI-Scripts PR (optional) Notes
9/21/2017 1.0 1308015 New Syslog KB
       

 
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