We are using SNMP on UCS and our monitoring works fine. The only "annoying" thing is that about every 20 min there's an Authentication Error message in the logs on both 6120's:
Trap received from xxFIPRUCS-A[10.137.0.xx] : SNMPv2-MIB::authenticationFailure [126.96.36.199.188.8.131.52.5.5]
We were able to re-create this error by polling the wrong community string.
The question however is: Is there any way in UCS via CLI or GUI to find out who is polling? IP address?
Could you fill us in on what you are polling in general and what system (like Cacti/Zenoss etc) you are using? Have you been able to poll the vNIC and vHBA traffic? I cannot find an OID that works for those.
Please see this older post: https://supportforums.cisco.com/message/3420470#3420470
Is it possible that some orchestration software is attempting to connect every 20 minutes (Guessing)? May be if you can do a tcpdump or wireshark and capture these packets to identify the source of login attempt.
Regarding SNMP Polling it would be great if you could share the useful OID's which you are currently polling for the UCS. Also are you processing SNMP Traps as well for faults?
Get SolarWinds it has integration with UCS. Best thing ever, and effortless to setup. Worth every penny.