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20 User Guide
Link Loss Return
Both ports on the Radiance multi-rate interface line card are designed with Link
Loss Return functionality for troubleshooting remote connections. When LLR is
enabled
*
, the port’s transmitter shuts down if its receiver fails to detect a valid
link signal. LLR should only be enabled on one end of a cable and is typically
enabled on either the unmanaged or remote device. LLR works in conjunction
with LLCF.
The diagram below shows a typical network configuration with good link status
using two Radiance multi-rate line cards for remote connectivity. Note that LLR
and LLCF are enabled as indicated in the diagram.
Management
Station
Remote
Station
Switch/Hub
w/SNMP
Switch/Hub
w/SNMP
Remote
Cable
LED lit = established link LED unlit = no link
LLCF is ON
LLR2 is ON
LLR1 is OFF
LLCF is ON
LLR1 is ON
LLR2 is OFF
Port 2 Port 1
Port 1 Port 2
Multi-Rate
Line Card A
Multi-Rate
Line Card B
If a connection breaks, the line cards will carry that link loss forward to a
switch/hub which generates a trap to the management station. The network
administrator can then determine the source of the problem.
Management
Station
Remote
Station
Switch/Hub
w/SNMP
Switch/Hub
w/SNMP
Link Loss Returned
Link Loss Carried Forward
Link Loss Carried Forward
LED lit = established link LED unlit = no link
Broken
Conductor
LLCF is ON
LLR1 is ON
LLR2 is OFF
LLCF is ON
LLR2 is ON
LLR1 is OFF
Port 1
Port 1
Multi-Rate
Line Card A
Multi-Rate
Line Card B
IMPORTANT: