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4. LINK PASS THROUGH FUNCTION
The LFP function includes the Link Fault Pass Through function (LLCF/LLR) and the DIP Switch design. LLCF/LLR can
immediately alarm administrators the problem of the link media and provide efficient solution to monitor the net. The DIP
Switch provides disable or enable the LFP function.
LLCF (Link Loss Carry Forward) means when a device connected to the converter and the TP line loss the link, the
converter’s fiber will disconnect the link of transmit. LLR (Link Loss Return) means when a device connected to the con-
verter and the fiber line loss the link, the converter’s fiber will disconnect the link of transmit. Both can immediately alarm
administrators the problem of the link media and provide efficient solution to monitor the net.
4.1 Link Loss Carry Forward (LLCF)
The FST-81x modules incorporates an LLCF function for troubleshooting a remote connection. When LLCF is enabled, the
FL / TP ports do not transmit a link signal until they receive a link signal from the opposite port.
The diagram below shows a typical network configuration with a good link status using FST-81x for remote connectivity.
Note that LLCF is enabled on DIP switch.
Management Switch/Hub Media Media Switch/Hub Management
Station w/SNMP Converter Converter w/SNMP Station
●
LED lit = established link
○
LED unlit = no link
If the connection breaks, FST-81x that link loss forward to the switch/hub which generates a trap to the management sta-
tion. The administrator can then determine the source of the problem.
Management Switch/Hub Media Media Switch/Hub Management
Station w/SNMP Converter Converter w/SNMP Station
●
LED lit = established link
○
LED unlit = no link
#
Notice:
The FST-81x is shipped with the default LFP (LLCF/LLR) function disable. This feature can also be turned on on-purpose.
If you are familiar with the network installation and for diagnostic purpose (i.e. check which end is broken), you can turn it on
and the converter will take effect immediately. Otherwise, please remain it in the default position.
LLCF is ON
LLCF is ON
TP
Fiber
Cable
TP
LLCF is ON
LLCF is ON
TP
Broken
Fiber
TP