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Syslog message: XMCHIP.*LI.*Received cookie size different from expected



Article ID: KB31679 KB Last Updated: 06 Oct 2021Version: 3.0

The "Received cookie size different from expected" message reports a transient hardware or LUCHIP/XLCHIP software issue.

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 "Received cookie size different from expected" event occurs, a message similar to the following is reported:

Apr 5 14:48:13.599 router0 fpc10 XMCHIP(0): LI1: Received cookie size different from expected


  1. Permanent impact of packet forwarding.
  2. This will usually also trigger event KB31602 - Syslog message: XMCHIP.*DRD.*Command sequence error.



It is transient hardware or LUCHIP/XLCHIP ucode software defect. The parcels (i.e. internal commands) from LUCHIP/XLCHIP to XMCHIP (Center Chip) is having errors or the size is incorrect. This is typical due to a bad HSL2 link (High Speed Link) and having large number of CRC errors. PR1166479 fixed HSL2 reliability transport for MPC6E cards. The HSL2 retransmission (Reliability Transport) is enabled for the links between LUCHIP/XLCHIP and XMCHIP. There was a software bug with this configuration and is addressed by PR1161194.  



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 "Received cookie size different from expected" message. Frequently these events help identify the cause.

    • An RMA is required only if a high rate of HSL2 CRC errors are reported. Check CRC errors using show pfe statistics error or check for CRC errors in pfe.debug file in /var/tmp/.

    • Check if HSL2 errors occur between the LU/XL and XM HSL2 links.
      • If so, this is an indication that it is either a hardware transient error or bad hardware. In this case, please restart the MPC and monitor if the error is repeatedly seen. If so, then the FPC should be RMA’ed.

    • If there are no HSL2 errors for LUCHIP/XLCHIP and XMCHIP links, then it is possible that this is a LUCHIP/XLCHIP ucode software defect. Check for LU/XL errors (PPE timeouts).

    • Contact your technical support representative for more analysis.

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

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:
2019-10-14: Article reviewed for accuracy; no changes required.
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