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6. LINK PASS THROUGH FUNCTION
The LFP function includes the Link Fault Pass Through function (LLCF/LLR). LLCF/LLR can immediately alarm adminis-
trators the problem of the link media and provide efficient solution to monitor the net.
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.
6.1 Link Loss Carry Forward (LLCF)
The 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-8/GST-7 Media Converter
boards for remote connectivity.
Management Switch/Hub Media Media Switch/Hub Management
Station w/SNMP Converter Converter w/SNMP Station
●
LED lit = established link
○
LED unlit = no link
LLCF is ON
LLCF is ON
TP
Fiber
Cable
TP
If the connection breaks, FST-8/GST-7 Media Converter boards that link loss forward to the switch/hub which generates a
trap to the management station. The administrator can then determine the source of the issue.
Management Switch/Hub Media Media Switch/Hub Management
Station w/SNMP Converter Converter w/SNMP Station
●
LED lit = established link
○
LED unlit = no link
LLCF is ON
LLCF is ON
TP
Broken
Fiber
TP
