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Error Handling by Fabric OAM

 

Fabric Operation, Administration, Maintenance (OAM) feature helps in detecting failures in fabric paths. Fabric OAM validates the fabric connectivity before sending traffic on a fabric plane whenever a new fabric path is brought up for a PFE. If a failure is detected, the software reports the fault and avoids using that fabric plane for that PFE. This feature works by sending a very low packets per second (PPS) self-destined OAM traffic over each of the available fabric planes and detecting any loss of traffic at the end points (fabric self-ping check).

Note

The feature is enabled by default. You can disable the feature by using the CLI command set chassis fabric oam detection-disable.

The Fabric OAM checks are done at boot time. The failed paths are disabled. The system does not do any recovery action by itself. However, you can try to recover the affected fabric planes by restarting the SIBs. The recovery steps depend on the nature of the failure.

When the same fabric planes fail on a single or multiple FPCs, restart the SIB containing the failed planes, using the following commands:

user@host> request chassis sib slot slot-number offline
user@host> request chassis sib slot slot-number online

When random fabric planes fail on multiple FPCs, the fault cannot be isolated to a specific FPC or SIB. However, you can try to recover the planes by restarting the SIBs that contain the affected planes in a sequential manner.

For each error detected by the fabric OAM feature, a syslog is generated. The following is an example:

The following syslog message indicates that a fabric OAM-related error was cleared.

Also, you can use the CLI commands show system errors active detail and show system alarms to view the Fabric OAM-related errors.

user@router> show system alarms

The following output shows details for both single fabric plane failure (on Packet Forwarding Engine 0) and all fabric planes failure (on Packet Forwarding Engine 1).

user@router> show system errors active detail

You can use the CLI command show chassis fabric fpcs to view the fabric OAM self-ping state of each fabric plane.

user@router> show chassis fabric fpcs

The show chassis fabric fpcs command displays the following output when the fabric OAM feature is disabled:

user@router> show chassis fabric fpcs