OTDR, optical power meters and light sources
A laser beam in an optical fiber, what can you do with that? Well, if you send the signal from an OTDR will it be reflected and the OTDR will give you the distance to connectors, splices and fiber breaks or ends. It will also give you the attenuation of the signal in the fiber. A transmitter in one end and a receiver in the other will give you the attenuation of the link, since the receiver will read the power of the incoming light. This will indicate if the traffic will come through as planned.