PLANET FST-80x Series - Manual (Page 12)

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
converter 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-80X 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-80X 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
LLCF is ON LLCF is ON
TP Fiber
Cable
TP
If the connection breaks, FST-80X 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 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
LLCF is ON
LLCF is ON
TP Broken
Fiber
TP
#
Notice:
1: When connecting FST-80X with LLCF enabled to an auto-negotiating-capable device, force both sides of the
configuration to 10 or 100Mbps full or half duplex. This allows the converter to immediately see link pulses and start
passing data.
2. Units are shipped with the LLCF function disabled (DOWN).
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