This reports the type of SFP/transceiver module currently plugged into this physical FC port, as identified by the hardware itself. For this port, xcvrType is checked against Cisco's supported-transceiver list whenever a port refuses to come up despite looking properly cabled, since an unsupported or mismatched transceiver type is a frequent, easily-overlooked cause. For example, an xcvrType reporting a short-range multimode optic on a port intended for a long-haul single-mode link explains immediately why that link won't reach its far end.