The "FI: Cell underflow errors with reorder engine pointers stalled" message reports that the reorder engine pointers are stalled on the egress PFE resulting in cell underflow errors or cell timeout errors to also get reported.
When a "FI: Cell underflow errors with reorder engine pointers stalled" event occurs, a message similar to the following is reported:
%PFE-5: fpc10 Performing action get-state for error /fpc/10/pfe/0/cm/0/XMCHIP(0)/0/XMCHIP_CMERROR_FI_INT_REG_LATE_CELL_WITH_RDR_PTR_STALLED (0x7013a) in module: XMCHIP(0) with scope: pfe category: functional level: major
Indications:
Service Impact: Persistent drop of packets.
"FI reorder cell timeout" and "FI Cell underflow errors" might also be reported at same time.
The Fabric input block in each PFE maintains a re-order pointer for each fabric stream ( fabric stream is a number derived from the destination FPC and PFE ). If the incoming cell has a sequence number which is higher than this reorder pointer, the cells are believed to have arrived early and the cell timeout logs are reported. Due to transient issue the reorder engine resposible for maintaining pointers for each of the fabric stream may get stalled resulting in other Fabric Input errors getting reported for the PFE.
This is a transient hardware issue. A major eror alarm will be raised once threshold of 1 is hit.
Once the major error alarm is raised, pfe-disable action will trigger bringing-down all interfaces mapped to affected pfe.
This issue can be due to a communication/fabric issue between an SCB and an XM chip-based FPC card or a faulty hardware.
Perform these steps to determine the cause and resolve the problem (if any). Continue through each step until the problem is resolved.
Collect the show command output.
show log messages
show log chassisd
show chassis environment cb
show interfaces terse
show services sessions count
show chassis fabric map
show chassis fabric plane
show chassis fabric plane-location
show chassis fabric summary
show chassis fabric sibs
show chassis fabric fpcs
show chassis fabric reachability detail
show pfe statistics traffic
show pfe statistics traffic fpc #
start shell pfe network fpc#
show syslog messages
show nvram
show pfe statistics error
show xmchip <pfe-id> fi stats
show xmchip <pfe-id> fo stats
show xmchip <pfe-id> wi stats 0
show xmchip <pfe-id> wo stats 0
show xmchip <pfe-id> wi stats 1
show xmchip <pfe-id> wo stats 1
exit
Analyze the show command output.
In the show log messages output, review the events that occurred at or just before the appearance of the "FI: Cell underflow errors with reorder engine pointers stalled" message. Frequently, these events help identify the cause.
Generally "FI Cell underflow errors" and "FI Reorder cell timeout errors" might be seen just before this alarm is reported.
Determine the FPC originating the bad packets.
If multiple syslogs from the same FPC are listing different stream numbers, then the FPC originating the logs is the potentially faulty FPC.
If multiple syslogs from many FPCs or PFEs are listing the same stream number, then map the stream number to the originating FPC.
Reset the FPC determined in the step above.
If the logs recur after reset, contact your technical support representative immediately.