On MX Series routers, EX9200 line of switches, and SRX series devices with an XM chipset-based line card installed, when the line card experiences the CMERROR "XMCHIP_CMERROR_FI_PAR_PROTECT_FSET_REG_DETECTED_TIMER_SRAM", the disable-pfe action will be involved. This issue causes the Packet Forwarding Engine to be disabled and traffic lost.

Traffic impact or PFE packet forwarding is permanently compromised if errors are seen repeatedly and the PFE is disabled as this error was classifies as a Major error.
 

* On the XM chipset based line cards (e.g., MPC3E/4E/5E/6E/NG-MPC2E/3E/EX9200-32XS/EX9200-6QS etc.)
* Experiencing the CMERROR "XMCHIP_CMERROR_FI_PAR_PROTECT_FSET_REG_DETECTED_TIMER_SRAM"

Here is a snippet of log for reference from issue period:
root@root> show chassis alarms no-forwarding
1 alarms currently active
Alarm time Class Description
2022-09-13 23:22:50 BST Major FPC 7 Major Errors - XM Chip Error code: 0x70131

Logs:
Sep 13 23:21:23 ROOT_RE0 inetd[13916]: /usr/sbin/sshd[68060]: exited, status 255
Sep 13 23:22:50 ROOT_RE0 fpc7 XMCHIP(0): XMCHIP(0): FI: Protect: Log Error 0x40, Log Address 0x10, Multiple Errors 0x0 
Sep 13 23:22:50 ROOT_RE0 tnp.tftpd[68098]: tftp : filename, /var/tmp/pfe_debug_commands
Sep 13 23:22:50 ROOT_RE0 chassisd[13902]: FPC 7 sent action 0x44 that is not configured 0x2 
Sep 13 23:22:50 ROOT_RE0 alarmd[14534]: Alarm set: FPC color=RED, class=CHASSIS, reason=FPC 7 Major Errors - XM Chip Error code: 0x70131
Sep 13 23:22:50 ROOT_RE0 craftd[13908]: Major alarm set, FPC 7 Major Errors - XM Chip Error code: 0x70131
Sep 13 23:22:57 ROOT_RE0 fpc7 PFE 0: 'PFE Disable' action performed. Bringing down ifd xe-7/0/0 256 
Sep 13 23:22:57 ROOT_RE0 fpc7 PFE 0: 'PFE Disable' action performed. Bringing down ifd xe-7/0/1 257 
Sep 13 23:22:57 ROOT_RE0 kernel: if_msg_ifd_cmd_tlv_decode ifd xe-7/0/0 #256 down with ASIC Error
Sep 13 23:22:57 ROOT_RE0 fpc7 PFE 0: 'PFE Disable' action performed. Bringing down ifd xe-7/0/2 258
Sep 13 23:22:58 ROOT_RE0 fpc7 Cmerror Op Set: XMCHIP(0): XMCHIP(0): FI: Protect: Parity error for timer SRAM (Timeout periods may be affected)  
Sep 13 23:23:06 ROOT_RE0 fpc7 CMIC(7/0) link 0 SFP laser bias current low alarm set 

Reclassify the CMERROR "XMCHIP_CMERROR_FI_PAR_PROTECT_FSET_REG_DETECTED_TIMER_SRAM" from major to minor since there is no functional impact with this error, so disable-pfe action is not necessary to be involved.

Workaround:
From Junos 17.4 or above, reclassify this error id as a workaround. This configuration needs to be done for each line card with XMCHIP. Here is an example for FPC3: 
[edit chassis fpc 3] 
+ error {
+        "/fpc/3/pfe/0/cm/0/XMCHIP(0)/0/XMCHIP_CMERROR_FI_PAR_PROTECT_FSET_REG_DETECTED_TIMER_SRAM { 
+             severity minor; 
+         }

Restoration steps:
Reboot the affected FPC to recover
Refer PR1463928  for more details

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