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[QFX/PTX] FPC Major alarm - 'PE Error code: 0x2101aa'

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Article ID: KB36020 KB Last Updated: 29 Jun 2020Version: 1.0
Summary:

This article explains the reason for the occurrence of FPC major alarm with "PE Error Code: 0x2101aa", the troubleshooting steps and how to clear the alarm.

Symptoms:

Active alarms:

user@host> show chassis alarms
2 alarms currently active
Alarm time               Class  Description
2019-10-19 09:52:22 UTC  Major  FPC x Major Errors - PE Error code: 0x2101aa
2019-10-19 09:52:22 UTC  Major  FPC y Major Errors - PE Error code: 0x2101aa

Error:‚Äč

Oct 19 09:52:22.856  alarmd[5474]: %DAEMON-4: Alarm set: FPC color=RED, class=CHASSIS, reason=FPC 6 Major Errors - PE Error code: 0x2101aa
Oct 19 09:52:22.856  craftd[5475]: %DAEMON-4: Receive FX craftd set alarm message: color: 1 class: 100 object: 104 slot: 6 silent: 0 short_reason=FPC 6 Major Errors long_reason=FPC 6 Major Errors - PE Error code: 0x2101aa id=150996584 reason=150994944
Cause:
  1. CRC (Cyclic Redundancy Check) Error
  2. BER (Bit Error Rate) trigger
Solution:

The Error Messages just before the alarm was triggered:

Oct 19 09:52:22.000  %USER-3: fpc6 fpc6 dcpfe: Cmerror Op Set: PE Chip: PE2[2]: EPW: crc error#012
Oct 19 09:52:22.807  %PFE-3: fpc6 Cmerror Op Set: PE Chip: PE2[2]: EPW: crc error 
Oct 19 09:52:22.856  alarmd[5474]: %DAEMON-4: Alarm set: FPC color=RED, class=CHASSIS, reason=FPC 6 Major Errors - PE Error code: 0x2101aa
Oct 19 09:52:22.856  craftd[5475]: %DAEMON-4: Receive FX craftd set alarm message: color: 1 class: 100 object: 104 slot: 6 silent: 0 short_reason=FPC 6 Major Errors long_reason=FPC 6 Major Errors - PE Error code: 0x2101aa id=150996584 reason=150994944
Oct 19 09:52:22.856  craftd[5475]: %DAEMON-4:  Major alarm set, FPC 6 Major Errors - PE Error code: 0x2101aa
Oct 19 09:52:43.000  %USER-3: fpc6 fpc6 dcpfe: Cmerror Op Set: PE Chip: PE2[2]: EPW: crc error#012
Oct 19 09:52:43.232  %PFE-3: fpc6 Cmerror Op Set: PE Chip: PE2[2]: EPW: crc error 
Oct 19 09:53:49.000  %USER-3: fpc6 fpc6 dcpfe: Cmerror Op Set: PE Chip: PE2[2]: EPW: crc error#012

EPW is the egress packet write block within the  PE chip. CRC check will be performed on every packet in the EPW block on the egress path. If the check fails, then the CRC error will be reported.

The “CRC errors” are caused when  FPC/DPC or Control Board (CB) might not be allowing transit traffic to be handled as expected, thereby causing an incorrect CRC value to be sent with traffic going through the switch fabric.  Although the log message refers to a Flexible PIC Concentrator (FPC), such a reference does not necessarily mean that part is faulty, but only that an issue was detected in the received traffic.

Indications:

  1. For the EPW CRC error, even if we see a single CRC error on EPW, it will be reported.
  2. This alarm will be automatically cleared if no new CRC errors are reported in the next 90 seconds in the EPW block.
  3. If not, the alarm will be raised.
  4. There should be no impact if there is a single occurrence of this incident.

The error code 0x2101aa corresponds to the Egress Packet Writer CRC error. The Egress Packet Writer is the block within PE chip which receives the packets from the Fabric Input block, checks the CRC, BER, and writes the packet to the memory buffer.

You may also see BER errors along with CRC errors in certain cases. BER is reported as and when bit errors are detected. This could be due to a transient issue with the transit packet.

Example Logs:

Feb 20 20:55:41.907  fpc6 CCL: 1 CRC errors seen on link PE2-Avg-28nm-link-9-17
Feb 21 03:04:03.213  fpc6 CCL: 2 BER errors seen on link PE2-Avg-28nm-link-9-17

Ideally, the alarms will clear on their own if it occurs infrequently but the errors will remain in the logs. In case the errors frequently occur and alarms are triggered and getting cleared frequently, you may consider restarting the FPC.

Restart FPC:

user@host> request chassis fpc (offline | online | restart) slot slot-number

 

Here,

user@host> request chassis fpc restart slot 6

If the error still persists post restart and alarms do not clear and contact JTAC Support. This might need detailed investigation to rule out possibility of permanent hardware error due to issue on the chip level.

 

 

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