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Cisco Bug: CSCvu97916 - On NCS55xx, PFCWD actions are inconsistent across different egress queues for same source port/flow

Last Modified

Jul 21, 2020

Products (1)

  • Cisco ASR 9000 Series Aggregation Services Routers

Known Affected Releases

6.6.4.BASE

Description (partial)

Symptom:
On NCS55xx, when a PFC storm happens simultaneously across different destination ports
on traffic-classes (queues) receiving traffic from the same source port, then the PFCWD
behavior across these queues is inconsistent

Few of the queues may move between WD expiry and normal (monitoring) state while
some may get shutdown. Eventually, all queues experiencing the PFC storm will shutdown

Conditions:
PFC needs to be enabled on all the egress interfaces and the single
source port bringing in traffic into the NCS55xx router

PFC WD needs to be enabled on all of the above interfaces.
Note that PFC WD is enabled by default when PFC is enabled and
has to be explicitly turned off.

The issue is only seen when several of the destination ports experience
PFC storm on the same TC simultaneously
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Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
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