IMC Networks iMcV-LIM Operation Manual page 9

FiberAlert (FA)
FiberAlert minimizes the
problems associated with the
loss of one strand of fiber. If a
strand is unavailable, the IMC
Networks device at the
receiver end notes the loss of
link. The device will then stop
transmitting data and the link
signal until a signal or link pulse
is received. The result is that the link LED on BOTH sides of the fiber connection will
go out indicating a fault somewhere in the fiber loop. Using FiberAlert, a local site
administrator is notified of a fault and can quickly determine where a cable fault is
located.
Enable FiberAlert at the remote side of a media conversion only. Enabling it on both
sides would keep both transmitters disabled indefinitely.
By default FA is disabled. When enabled if, a fault occurs on the fiber line, affecting
data in one direction, FA stops sending signal in the opposite direction. FXLL will act
on this lack of signal, propagating the loss of like to the copper port when FXLL is
enabled.
Far End Fault
By default, FEF is disabled. When enabled, and a fault occurs on the fiber line,
affecting data in one direction, an FEF signal will be sent in the opposite direction,
indicating the fault. FXLL will act on this signal propagating the loss of link to the
copper port when FXLL is enabled.
FEF versus FA
FEF is preferred when the devices at both ends of the fiber can interpret the FEF
signal. This allows FEF to be turned on at both ends, which will engage the FEF
regardless of which direction the fault occurs. (Please refer to diagram on previous
page) For example if a fault should occur on segment 2 in the direction of segment 1
to 3, FEF would be engaged on the iMcV-LIM between segment 2 and 3. This would
then send a signal back to the iMcV-LIM between segment 1 and 2. If the iMcV-LIM
between segment 1 and 2 is in a managed chassis, the chassis would send a trap that
the port is down. Alternatively, if the iMcV-LIM is not in a managed chassis, FXLL
could be engaged to propagate the fault onto the copper port; this would cause
segment 1 to show no link on both ends.
WARNING
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