The article will explain about below alarm:

"Major CB * Fabric Chip * Failure,"

Below alarm will be reported by chassis, it can come as single or can come with other alarms as well.

root@> show chassis alarms no-forwarding
2024-10-21 22:46:15 UTC Minor CB 2 Volt Sensor Fail
2024-10-21 22:45:30 UTC Minor CB 2 PMBus Device Fail
2024-10-21 22:43:48 UTC Minor CB 2 Temp Sensor Fail
2024-10-16 14:26:19 UTC Major CB 2 Fabric Chip 0 Failure
2024-10-16 14:26:13 UTC Major CB 2 Fabric Chip 1 Failure

root@> show chassis fabric summary no-forwarding
Plane   State    Uptime
 0      Online   235 days, 5 hours, 6 minutes, 46 seconds
 1      Online   235 days, 5 hours, 6 minutes, 46 seconds
 2      Online   235 days, 5 hours, 6 minutes, 46 seconds
 3      Online   235 days, 5 hours, 6 minutes, 46 seconds
 4      Fault    6 days, 11 hours, 5 minutes, 59 seconds
 5      Fault    6 days, 11 hours, 6 minutes, 6 seconds
Log messages:
Oct 23 00:39:03.044  chassisd[8765]: %DAEMON-3: fm_hsl2_fasic_init: Plane 7 re-init failed in attempt 3
Oct 23 00:39:03.739  alarmd[8905]: %DAEMON-4: Alarm set: CB id=167772534, color=RED, class=CHASSIS, reason=CB 2 Fabric Chip 1 Failure
Oct 23 00:39:03.743  alarmd[8905]: %DAEMON-4: Alarm set: CB id=117440886, color=RED, class=CHASSIS, reason=CB 2 Fabric Chip 0 Failure
Oct 23 00:39:03.763  craftd[8768]: %DAEMON-4: Major alarm set, CB 2 Fabric Chip 1 Failure
Oct 23 00:39:03.776  craftd[8768]: %DAEMON-4: Major alarm set, CB 2 Fabric Chip 0 Failure

Chassisd logs:

Oct 23 00:37:34 FM: End of Multi link train fabric event for pb_mask 0xfffff, plane_mask 0x1, evq=0x0
Oct 23 00:37:34 send: yellow alarm set, device CB 2, reason CB 2 Fabric Chip 0 Not Online
Oct 23 00:37:34 CHASSISD_SNMP_TRAP10: SNMP trap generated: fabric plane offline (jnxFruContentsIndex 12, jnxFruL1Index 2, jnxFruL2Index 0, jnxFruL3Index 0, jnxFruName CB 2, jnxFruType 5, jnxFruSlot 1, jnxFruOfflineReason 2, jnxFruLastPowerOff 0, jnxFruLastPowerOn 12373)
Oct 23 00:37:34 send: yellow alarm set, device CB 2, reason CB 2 Fabric Chip 1 Not Online
Oct 23 00:37:34 CHASSISD_SNMP_TRAP10: SNMP trap generated: fabric plane offline (jnxFruContentsIndex 12, jnxFruL1Index 2, jnxFruL2Index 0, jnxFruL3Index 0, jnxFruName CB 2, jnxFruType 5, jnxFruSlot 1, jnxFruOfflineReason 2, jnxFruLastPowerOff 0, jnxFruLastPowerOn 12373)
Oct 23 00:37:34 fabric_mx_complete_multi_link_train Marked links trained for slot 0, eptr->ev_aux_slot 0xffff sublc 0 of event Plane online

Potential Causes:

- Poor connections or issues with the backplane interconnects can cause communication failures between the CB and other components, leading to fabric chip failures. Ensure CB1 is properly connected. Physically reseating the CB can sometimes resolve issues caused by poor connections.

- Insufficient or unstable power supply to the CB can cause it to malfunction, leading to failures in the fabric chips. Check that the power supply is stable and within the recommended specifications for the device. Insufficient or unstable power can cause the CB to malfunction.

- Overheating due to inadequate cooling or environmental factors can cause the CB and its fabric chips to fail. Check the cooling system, including fans, air filters, and airflow, to ensure the device is not overheating. Overheating can cause the CB and its fabric chips to fail.

- The Control Board (CB) might be experiencing a hardware malfunction or has failed entirely, leading to a major failure alert. Specific fabric chips on the CB (Fabric Chip 0 and Fabric Chip 1) might be malfunctioning due to hardware defects or degradation over time. If reseating and other troubleshooting steps do not resolve the issue, the CB or fabric chips might need to be replaced.

Workaround:

1. Offline/online the CB.

> request chassis cb offline slot <>

> request chassis cb online slot <>

2. Physical reseat of the CB.

3.Collect the output for the below commands:

> show chassis alarms

> show chassis fabric plane

> show chassis fabric map

> show log messages| match fabric

> show log chassisd | match fabric

Conclusion:

Addressing the "CB Fabric Chip Failure" messages involves a thorough inspection and troubleshooting process.

By reseating the CB, verifying the power supply, and ensuring proper cooling, many issues can be resolved.

However, persistent problems may require component replacement.

If you need further assistance, please contact Juniper support.