Fibre Loopback assemblies provides a media of return path for a signal, whether the signal is for testing purposes or due to network restoration. In the case of testing, the loopback signal is used for diagnosing a problem. Sending a loopback test to a network equipment, one at a time, is a technique for isolating a problem.Its performance is as good as that of a general patchcord. Loopback assemblies are avalible with FC, SC, ST, LC, MU, MT/RJ, Escon, and FDDI connectors.