Far End Fault Feature - FibroLAN FEM4 User And Installation Manual

Advanced FE/E1 Fiber Converters
6 – 100Base-FX Far End Fault (FEF feature)
Usually a "LINK" indication is related to the incoming fiber only: F/O Link ON shows
that the path created by the remote transmitter, local receiver and the fiber connecting
them is operational. However if there is a fault in the other – outgoing - path (created
by the local transmitter, remote receiver and the fiber connecting them) – the indication
for such fault can be seen on the remote device only.
The FEF implemented in the FEM/FEM4 devices close this gap: if there is a fault in the
incoming receive path of the lower FEM/FEM4 (see drawing below), then the F/O
Link/Act LED will go OFF on both FEM/FEM4 devices. In this way we avoid the
possibility of having a FX Link ON indication at one end, while, in reality one of the F/O
data path is disrupted. The following drawing depicts the FEF functionality.
The FEF Feature is always enabled and functional in FEM/FEM4 devices
14