Nexus 9300 shows IF_DOWN_LINK_FAILURE

[roellinl]

Hi, I'm currently working on a Nexus9000 C93108TC-FX and trying to measure the time it takes for the ports to start. During the experiments, I found that the ports sometimes take way longer to start. I was digging through the log files to find that when it happens the router reports an IF_DOWN_LINK_FAILURE (shown in attachment). The router reports the port to be up then reports the failure and starts power cycling the port until at some point it is up again. Is this expected behavior or is it some sort of a bug?

I'm aware that the constant turning on and off of the ports for the experiment could trigger some failure detection but it kind of seems to happen at random and it also seems weird that the router just starts power cycling the port.

Any help or pointers to what exactly is happening would be appreciated.

[MHM Cisco World]

https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/6-x/qos/configuration/guide/b_Cisco_Nexus_9000_Series_NX-OS_Quality_of_Service_Configuration_Guide/b_Cisco_Nexus_9000_Series_NX-OS_Quality_of_Service_Configuration_Guide_chapter_0...

I think this because the flow control ON/OFF in both side (mismatch)

[roellinl]

Thanks for the fast reply. I checked the configuration of the ports. Input and output flow control is deactivated on both sides. I'm not sure if you are referring to that or not. But it should not interfere if it is turned off right? (I'm not really familiar with this feature) 

[MHM Cisco World]

https://mwhubbard.blogspot.com/2018/04/nexus-9k-ethport-5-ifdownlinkfailure.html?m=1

For flow control it OK if it disable' not need to enable.

[roellinl]

Thanks that looks like a similar problem to mine. I will check if disabling the auto negotiation feature will help.

[MHM Cisco World]

You are so welcome friend 

MHM

[roellinl]

I disabled the auto negotiation completely on the interfaces and I still get the same behavior. It even seems to happen a bit more often. So it has to be something else.