This string holds the Dn of the underlying physical endpoint object that this VSAN's endpoint on an FCoE member port is built on top of. Because this VSAN's endpoint on an FCoE member port is itself a logical mapping rather than a physical port, an admin follows this epDn to jump from the logical object down to the actual physical port/interface object where cabling, transceiver, and low-level counters live. It would point at something like a physical port Dn nested under a fabric interconnect's fixed-module path.