OPERATIONAL DEFECT DATABASE
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A Nexus 9000 Series Switch with Cloud-Scale ASIC architecture (-EX, -FX, -FX2,(not GX, not GX2b) etc) may experience a condition where interface microflaps lead to the switch being unable to pass any traffic from either the control-plane or the data-plane. In this condition, buffer exhaustion syslogs may or may not be seen. All control plane protocols will fail, and multiple interfaces may slowly increment output discards, even with little to no egress traffic shown for the interface's egress rate. "Microflaps" are link failures which occur and recover within the configured Link Debounce time (100ms by default). There are no syslog indications of a port experiencing microflaps, nor are microflaps often a cause for concern if they never lead to true link failure.
Nexus 9000 Series Switch Cloud-Scale ASIC Architecture (-EX, -FX, -FX2, N9K-C9332C, N9K-C9364C, -not GX, not GX2b etc) Port(s) repeatedly microflapping
- Reload - If condition is detected early enough, flapping the port experiencing the microflaps may recover the switch - If upgrading is not feasible, "link debounce time 0" can temporarily prevent a microflapping port from triggering the condition. This will disable the link debounce timer, and force a full reinitialization of the link in the event any loss of signal is detected. For a microflapping port, this may lead to rapid link failures, though the overall integrity of the switch will be maintained.
This issue was originally documented by CSCvy29240, however, the fix implemented in 9.3(8) does not appear to account for all possible microflap scenarios. As such, the issue may still be seen in 9.3(8) as well under some conditions.
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