This SnmpAdminString field holds the Distinguished Name of the source filter object that this FC monitor filter reference references. For a linking record inside an FC monitoring session's filter configuration that points at the actual filter object being applied, this pointer is what actually connects an abstract filter reference back to the concrete endpoint filter object doing the real work of narrowing down which traffic gets mirrored. This would resolve to the DN of a specific FcMonFiltEp object elsewhere in the same monitoring session's configuration, not to a port or VSAN directly.