Polling methods of Virtualization Manager and VIM
To display Virtualization Manager data of a specific configuration item (for example, a virtual machine) VIM polls Virtualization Manager for virtual machine equals. IVIM and Virtualization Manager both use different types of identifiers for the configuration items.
To make sure that the different types of identifiers are matched correctly, it is best practice in a VMware environment to always poll against the vCenter, instead of polling directly against the hosts.
IVIM polls against the vCenter (VMware) server, not against ESX servers on which virtual machines run. IVIM also provides a functionality that allows vCenter monitoring using CIM (Common Information Model).
This functionality enables SAM and NPM to get a token from the vCenter instead of using the credentials for the hosts, and use CIM to collect data even if you poll against the vCenter, and not against the hosts.
Neither SAM, nor NPM uses this functionality currently.