Link Loss Return (Llr) - METRObility Optical Systems RADIANCE 10/100MBPS ACCESS OPTICAL NETWORK UNIT Installation & User Manual

Link Loss Return (LLR)

The fiber optic port of the Access ONU has been designed with Link Loss
Return functionality
When LLR is enabled, the fiber port's transmitter shuts down if 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 a Radiance Access Line Card and an Access ONU for remote
connectivity.
Switch/Hub
PC
w/SNMP
LED lit = established link
If one of the optical conductors is bad (as shown in the diagram box below), the
unit with LLR enabled will return a no link condition to its link partner. This
aids the network administrator in determining the source of the loss.
Switch/Hub
PC w/SNMP
LED lit = established link
Important: LLR must not be active on both ends of a configuration. If it is, the
link can never be established.
*The unit is shipped with LLR disabled (OFF).
18 User Guide
*
for troubleshooting a remote connection.
Access
Line Card
LLR is OFF
LED unlit = no link
Access
Line Card
LLR is OFF
Conductor
Link Loss Returned
LED unlit = no link
Access
ONU
LLR is ON
Fiber
Cable
Access
ONU
LLR is ON
Broken
Fiber
Customer
Site
Customer
Site