Interlogix MC352-1P/1S - Manual (Page 17)

IFS MC352-1P/1S User Manual 13
* The factory default setting for the LFP function is "off".
Link Loss Return (LLR)
The fiber ports of the MC352-1P/1S have been designed with
an LLR function for troubleshooting a remote connection. LLR
works in conjunction with LLCF.
When the LFP function is enabled, the port’s transmitter shuts
down when its receiver fails to detect a valid connection. LLR
should only be enabled on one end of the link and is typically
enabled on either the unmanaged or remote device.
The diagram below shows a typical network configuration with
a good link status using MC352-1P/1S for remote connectivity.
Note that LLR and LLCF are enabled as indicated in the
diagram.
If one of the optical conductors is bad (as shown in the
diagram box below), the converter with LLR function will return