PLANET WFT-801 - Manual (Page 14)

12
Link Loss Return (LLR)
The fiber ports of WFT-80X have been designed with an 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 Smart Media Converter 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 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.
IMPORTANT: LLR must NOT be active on both ends of a
configuration. If it is, the link can never be
established.
*Units are shipped with the LLR function disabled (DOWN).
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