Description

This article provides more information about the parity errors that are seen within the KHT block of the TL Chip in the Flexible PIC Concentrator (FPC).

Symptoms

The occurrences of a KHT parity error can be checked by looking at the FPC syslog messages. Run the request pfe execute command "show syslog messages" target fpc#  (# indicates the FPC slot number) command, and the following log is printed for each occurrence: 

[May  7 11:27:13.594 LOG: Err] Cmerror Op Set: TL Chip: TL Chip KHT parity error
The system generates an alarm for KHT parity as "Major Errors - TL Chip Error code: 0x60004" after five repeated occurrences and logs such as the following are seen printed in the messages file: 
May  7 11:36:39.461  jtac-lab fpc2 TL Chip:TL Chip KHT parity error
May  7 11:36:40.557  jtac-lab alarmd[2566]: Alarm set: FPC color=RED, class=CHASSIS, reason=FPC 2 Major Errors - TL Chip Error code: 0x60004
May  7 11:36:40.557  jtac-lab craftd[2042]:  Major alarm set, FPC 2 Major Errors - TL Chip Error code: 0x60004

Solution

Parity errors usually occur due to electromagnetic interference or discharge, which creates a malformed cell that cannot hold the bit value or the charge representing it. KHT or the Key Hash Table is one of the blocks within the TL Chip, which enables the lookup function. Most of the parity errors are typically due to environmental conditions and are transient in nature.

The error described in this article shows a memory parity error within the KHT block.

The system identifies these errors as soon as they occur and attempts correction with a fault handling mechanism where the affected entry in the hardware is copied from shadow memory. This attempt continues until the affected entry is corrected. A major alarm is raised when the system detects this error for the sixth time after being unable to correct the error, so that the next corrective action can be taken such as performing an FPC reboot or replacing it following advice by a Support engineer if the error recurs.

Note: Minor packet loss would be seen for the duration of the parity error.

Use the command " request chassis fpc slot # restart " to restart the FPC in a safe window to recover from the error.

If the error persists, open a technical support case for further investigation and share the following outputs: 

  • show log messages
  • show log chassisd
  • start shell network pfe network <fpc#>
  • show syslog messages
  • show tlchip [X] trapstats verbose      <<2-3 times
  • show cmerror module brief
  • show cmerror module [X] error 0x60004
  • exit