metrobility-optical-syste radiance r231-17 User Manual
18
User Guide
Link Loss Return (LLR)
The fiber optic ports of the access line cards have been designed with an LLR
function
function
*
for troubleshooting a remote connection.
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.
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 access line cards for remote connectivity.
status using access line cards for remote connectivity.
*Units are shipped with the LLR function disabled (DOWN).
If one of the optical conductors is bad (as shown in the diagram box below), the
card 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.
card 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.
IMPORTANT: LLR must not be active on both ends of a configuration. If it is,
the link can never be established.
the link can never be established.
PC
Switch/Hub
w/SNMP
Customer
Site
Access
Line Card
Fiber
Cable
LED lit = established link
LED unlit = no link
LLR is OFF
LLR is ON
Access
Line Card
PC
Switch/Hub
w/SNMP
Customer
Site
Link Loss Returned
LED lit = established link
LED unlit = no link
Broken
Fiber
Conductor
LLR is OFF
LLR is ON
Access
Line Card
Access
Line Card