SNMP monitoring routing on a Nexus device
When monitoring routing protocols using SNMP on a Nexus device, in order for SNMP to find and use the existing OID, it is necessary to add a routing instance to the context like so:
snmp-server context default instance [routing_instance_name] vrf default
This is the case even if only one VRF is being used, that is, the default VRF. On the network monitoring side, you must add the same device multiple times with different SNMP communities and the corresponding OID for each one.
Links:
https://networklessons.com/cisco/ccie-routing-switching/introduction-to-snmp