troubleshooting nexus 7K

[Peter Kim]

I'm having an weird issue with my 7K nexus switches.  Started sometime ago, I can't suddenly ping some servers.  They are out for a minute or two and comes back.  I know servers are online.  Here is what I found.  When this happens, I can ping those servers from 7K-A switch but not from 7K-B.  On the log, it doesn't have much information why this is happening.  Cisco didn't find anything.  They suggested me to update the IOS.  Anyone had a similar issue?  If I didn't explain, please let me know what other information you need.  Thanks a bunch.

[Flavio Miranda]

Hello @Peter Kim

Wondering, first, ping fail only and exclusivity to those servers from Nexus ?

 Is there anything between those servers and the Nexus B ? 

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-If I helped you somehow, please, rate it as useful. - 

[Peter Kim]

Yes, ping fails to those server from one switch while they are pingable from the other switch.

[Flavio Miranda]

Got it. Is there anything between those server and the Nexus B that could justify this problem?  Or they are

directly connected ?

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[Peter Kim]

There are Fabric Interconnect switches connected between 7K A, B and those servers.

[Georg Pauwen]

Hello,

as far as I recall, the Nexus 7K has a default CoPP (Control Plane Policing)
service policy enabled that limits and actually aggressively polices ICMP
traffic.

You should be able to see the policy with the command:

show policy-map interface control-plane

Can you post the output of that command ?

[Peter Kim]

here is the output.  I don't think the policy-map is the issue.  Network connections just dropped without no reason for 30-50s.  No error logs.  Like I mentioned, you can ping from one switch but not from the other. 

[Georg Pauwen]

Hello,

30 to 50 seconds sounds like a spanning tree issue...

Can you post the configs of both switches ?

[Peter Kim]

I'm sorry for the late reply.  I was so busy to troubleshoot on other things.  Anyway, I can try to clean up my config and upload here.  By the way, I found one thing.  When I can't ping the server from 7K core switches, I noticed doing "clear ip arp X.X.X.X" will fix the issue temporary.  And of course, I lose the connectivity right after random.