The Packet Forwarding Engine divides packets into smaller units, known as cells, for more efficient processing. As the indicated F-chip on the indicated Control Board (CB) processed data, which was received from the indicated Packet Forwarding Engine (PFE) on the indicated Flexible PIC Concentrator (FPC), it dropped the indicated number of cells per second.

The isuse related to this syslog message is described in the following sections:

The CHASSISD_FASIC_INPUT_DROP message is logged, when the F-chip is reporting congestion.

When a CHASSISD_FASIC_INPUT_DROP event occurs, a message similar to the following is reported:

The log message may also be seen with the generation of one or more alarms. Possible alarms include the following:

Associated log messages are also recorded in the syslog.

The cause for such a notification may be due to either congestion when the cells are dropped inside an F-chip as the available spaces to store the cells being used up or the F-chip hardware being in a state that is not processing the cells as expected.

Examine the following output to help determine the cause of this message (select the log set based on the platform):

All platforms:







The above outputs will show which components are reporting F-chip errors. If a fabric plane has errors on two different Packet Forwarding Engines (PFEs), the issue is probably with the plane; which is the Control Board. If a PFE has errors on two different planes, the issue is probably the PFE; which is the FPC.

On some M-series and T-series platforms, additional information can be directly obtained from the fabric hardware, regarding where the F-chip errors are originating. If the system is referenced below, then collect the related listed output:

(Use only one of the following sets of commands)

Replace the above [unit#] entry with the Packet Forwarding Engine component for the router platform:

  • M10/M5: feb
  • M20: ssb#
  • M120: feb#
  • M40e/M160: sfm#
  • T-series: spmb#

The # character will need to be replaced with each installed component number for the router platform (i.e, sfm0, sfm1, sfm2, sfm3).

Perform the following procedure:

1. If the log message occurred only once or is sporadic, then the fabric hardware is performing as designed in handling temporary congestion of traffic.

2. If this issue is time critical or you need an root cause analysis, then open a case with your technical support representative to troubleshoot further. Otherwise the following steps can be used to attempt to resolve the issue.

3. Perform the following procedure during a maintenance window, as it will impact transit traffic:

  • Reset the associated components. Try the Control Board first and then the associated FPC.
  • Swap components on the system; that is, two Control Boards or FPC boards, to see if the issue follows that component.
  • If a known good spare component is available, swap the part to see if this resolves the issue.

4. If the F-chip messages continue at this point, open a case with JTAC for further investigation.

About the author


Leave a Comment