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Syslog message: XMCHIP(2): XMCHIP(2): EPM0: Packet delimiter violation detected - Queue 32



Article ID: KB36242 KB Last Updated: 29 Oct 2020Version: 2.0

The "XMCHIP(2): XMCHIP(2): EPM0: Packet delimiter violation detected - Queue 32" message reports a transient hardware issue.

This is a Troubleshooting article for a PFE ASIC Syslog Event.


Along with a "XMCHIP(0): EPM0: Packet delimiter violation detected - Queue 0", the following errors are reported:

fpc0 XMCHIP(2): XMCHIP(2): EPM0: Packet delimiter violation detected - Queue 32
fpc0 XMCHIP(2): XMCHIP(2): EPM0: Protect: Log Error 0x40, Log Address 0x1f78, Multiple Errors 0x40
fpc0 XMCHIP(2):XMCHIP(2): EPM0: Protect: Parity error for main data buffer 
Cmerror: Draining ASIC error message queue
  • Single occurrence of syslog, not seen with other events, indicates a one time hardware error. 
  • Multiple continuous occurrences with "EPM_PROTECT: Detected: Parity error for main data buffer" indicate persistent underlying issues and could impact the traffic.
  • Traffic impact or permanent impact of packet forwarding depending on the number of times syslog entry.
EPM is the Egress Priority-Flow-Control Manager Block. Normally, two blocks EPM0 and EPM1 to the server WAN interfaces of the PFE. Parity errors alone in the main data buffer cause a wedge in port-group which could impact the transient traffic if it happens multiple times.

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 pfe network <fpc#>
    show cmerror module
    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 "Enqueue upon free pool empty" message. These events frequently help identify the cause.

Modification History:
2020-10-28: Fixed typo in Solution item 1 (start shell network pfe <fpc#> To: start shell pfe network <fpc#>)
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