cucsSwEthLanBorderRn is the Relative Name (RN) of the LAN border domain on a Cisco UCS fabric interconnect, the object that groups its northbound Ethernet uplinks toward the customer network (a cucsSwEthLanBorder row) -- the naming fragment that distinguishes it from its sibling instances under the same parent object. UCS Manager builds the full DN by appending this RN to the parent's DN, so it is the piece an admin or script uses to tell the LAN border domain apart from others attached to the same parent. For instance, comparing the RN values under one parent quickly tells an admin which specific sibling -- among several instances of the same class -- the LAN border domain refers to.