This article provides a comprehensive guide to troubleshoot the issue of MX204 chassis alarm “FPC 0 offlined due to excessive resets”. The alarm triggers on the chassis when multiple major errors are reported on the FPC. Junos will make FPC offline when a trail of major errors is detected on the same FPC. It is important to identify the trigger of major errors to investigate the issue further.

The issue is characterized by the MX204 chassis alarm “FPC 0 offlined due to excessive resets”.

Traffic or permanent packet forwarding on the Packet Forwarding Engine (PFE) may be impacted.

Below major alarm is triggered when multiple major errors are reported on the FPC.
 

> show chassis alarms no-forwarding

1 alarms currently active
Alarm time               Class  Description
2023-12-15 14:22:40 WIB  Major  FPC 0 offlined due to excessive resets

chassisd[19700]: %DAEMON-5-CHASSISD_FRU_OFFLINE_NOTICE: Taking FPC 0 offline: Offlined due to major errors

alarmd[20031]: %DAEMON-4: Alarm set: FPC id=1694498920, color=RED, class=CHASSIS, reason=FPC 0 offlined due to excessive resets

Major Alarm: FPC 0 offlined due to excessive resets triggers on the chassis when multiple major errors are reported on the FPC. In response to the detection of a sequence of significant errors on the same FPC, Junos has initiated the action to deactivate FPC 0 to prevent further issues and safeguard system stability.

It is important to identify the trigger of major errors to investigate the issue further.

1) Identify the trigger of major errors by collecting below logs.

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

>show system core-dumps

>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 "ALARM" message. Frequently these events help identify the cause.

For an example:

Below log messages are observed before the major errors on the FPC.
 

%PFE-3: fpc0 Cmerror Op Set: PLL Error: LMK04808_MISC_LOS (URI: /fpc/0/pfe/0/cm/0/PLL_Error/0/PLL_CMERROR_MPC_LMK04808_MISC_LOS)

%PFE-5: fpc0 CMError: /fpc/0/pfe/0/cm/0/PLL_Error/0/PLL_CMERROR_MPC_LMK04906_WAN_LOS (0x170019), scope: board, category: functional, severity: major, module: PLL Error, type: LMK04906_WAN PLL LOS, oc_category: default

3) Please perform below troubleshooting in maintenances window and check the FPC status.

a) Restart the affected FPC.

Run the CLI command ‘ request chassis fpc slot # offline’,

Wait 30 seconds.

Then follow with the CLI command ‘ request chassis fpc slot # online’.

For more information on the command see: request chassis fpc.

b) Reseat the FPC in its slot. Use a flashlight to check for bent pins at this time.

c) Reboot chassis and check the status.

4) If the issue is seen repeatedly even after performing suggested workaround, open a Technical Service Request for further investigation and assistance