• Tools to use when you cannot expose the entire fiber optic cable:
– Fibre Channel loopback plug tests connectivity; many I/O controllers support loopback testing
– Power meters (optical dB meters) detect signal loss
– Optical Time Domain Reflectometer (OTDR) measures backscatter to locate faults—can pinpoint breaks to within meters, but is very expensive
Fibre Channel loopback plug
Power meter
OTDR
Optical Time Domain Reflectometer - (OTDR) - A test instrument that analyzes the light loss in an optical fiber. Used to find faults, splices and bends in the line, it works by sending out a light pulse and measuring its reflection. Such devices can measure fiber lines that are longer than 150 miles.