Which ONTAP ? SNMP tools such as snmpwalk do not function correctly with SNMP MIBs and Traps on cDOT/ONTAP. Also, some SNMP MIBs or Traps are deprecated in cDOT/ONTAP.
Please see TR-4220 for an overview of supported SNMP MIB/traps: (CTL+F look for OID)
https://www.netapp.com/media/16417-tr-4220.pdf