Symptom
A first generation N9K switch with RX link-local flow control (LLFC), matched by the presence of the following interface CLI 'flowcontrol receive on' and operating in the default cut-through switching mode (not 'switching-mode store-forward') may see output errors on ports when LLFC Pause frames are received.
Conditions
LLFC Receive enabled
Cut-through Switching mode enabled
This applies to the following PIDs only:
N9K-C93120TX, N9K-C93128TX, N9K-C9332PQ, N9K-C9372PX, N9K-C9372PX-E, N9K-C9372TX, N9K-C9372TX-E, N9K-C9396PX, N9K-C9396TX, N9K-X9408PC-CFP2, N9K-X9432PQ, N9K-X9464PX, N9K-X9464TX, N9K-X9464TX2, N9K-X9536PQ, N9K-X9564PX, N9K-X9564TX, N9K-X9636PQ.
Any NX-OS version up to 9.3(9).
Workaround
While in Cut-through mode, any flow control is not supported. Flow control operation otherwise is best-effort.
Disable LLFC, or change switching mode to Store-and-Forward. Reducing the number of incoming pause frames by addressing potential congestion on the connected device may also alleviate the volume of discards.
Further Problem Description
This problem is similar to the one previously discovered on N3200: CSCvx89285.
