On EX4400 platforms, due to an internal communication issue within the CPU controller, the system encounters repeated fxpc panics and causes dcpfe (Packet Forwarding Engine) process to crash and restart in continuous loop, bringing the system operationally down and resulting in complete service disruption.

This issue occurs on EX4400 platforms. An internal communication issue within the CPU controller disrupts normal system operations and leads to repeated FXPC panics. As a result, the dcpfe process crashes and continuously restarts, causing the device to become operationally down and resulting in a complete service disruption. This crashrestart loop continues until the system is rebooted.

To confirm the occurrence of this issue, check for the following via remote access (if available) or through console access:

1.The below repeated SMBus ioctl error can be identified using the cli command { show log messages | match SMBus ioctl failed }

Example log entries:

root@user> lcmd[18594]: %USER-3: smb_transfer: SMBus ioctl failed, retry:1 req:c01c6907 cmd:0x00 slave:0xac addr:0x56 errno=35, Resource temporarily unavailable 
root@user> lcmd[18594]: %USER-3: smb_transfer: SMBus ioctl failed, retry:2 req:c01c6907 cmd:0x00 slave:0xac addr:0x56 errno=35, Resource temporarily unavailable

2. The below FXPC panic logs can be identified using the cli command  { show log messages | match FXPC_PANIC }

Example log entries:

root@user>  dc-pfe[18587]: %USER-0-FXPC_PANIC: --------------------------------------
root@user>  dc-pfe[18587]: %USER-0-FXPC_PANIC1: PANIC PANIC PANIC PANIC PANIC PANIC
root@user>  dc-pfe[18587]: %USER-0: Traceback:
root@user>  dc-pfe[18587]: %USER-0-FXPC_PANIC: --------------------------------------

3. The core files can be verified using the cli command  "show system core-dumps"

4. If the switch is in Virtual-Chassis setup, its VC membership changes from Prsnt to NotPrsnt status, that can be verified by cli command show virtual-chassis

External-Trigger

This issue might be seen if the following conditions are met:
*On Junos EX4400 platforms

upgrade with fix of 1919727