PLANET MC-1610MR - Manual (Page 65)

6.2 Link Loss Return (LLR)
The LLR function for troubleshooting a remote connection. LLR works in conjunction with LLCF.
When LLR is enabled, the port’s transmitter shuts down when its receiver fails to detect a valid receive link. 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 FST-8 / GST-7 / GST-8 Media Con-
verter boards for remote connectivity.
Note that LLR and LLCF are enabled as indicated in the diagram.
Management Switch/Hub Media Media Switch/Hub Management
Station w/SNMP Converter Converter w/SNMP Station
● LED lit = established link ○ LED unlit = no link
Fiber
If one of the optical conductors is bad (as shown in the diagram box below), the converter with LLR enabled will return a no-link
condition to its link partner. With LLCF also enabled, the no-link condition is carried forward to the switch/hub where a trap is
generated to the management station, and the administrator can then determine the source of the loss.
Management Switch/Hub Media Media Switch/Hub Management
Station w/SNMP Converter Converter w/SNMP Station
● LED lit = established link ○ LED unlit = no link
Port 2
Broken
Port 1
Li k L C i d F d Li k L C i d F d
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