This is the relative name distinguishing this switch-side interface-configuration container from its sibling objects under the same parent interface. It matters on the switch-side interface-configuration container UCS Manager keeps for an internal fabric-interconnect interface because it's the fixed short suffix identifying this as the configuration child object rather than the interface object itself. An rn on this switch-side interface is what appends to a fixed parent interface path to form this configuration container's own address, the same way across every fabric-interconnect interface that has one.