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Radiance Multi-Rate Line Card 21
Link Loss Carry Forward
The Radiance multi-rate line card incorporates LLCF to assist in troubleshooting
a remote connection. When LLCF is enabled
*
, the ports do not transmit a signal
until they receive a signal from the opposite port. When a lost link signal is
returned to an unmanaged line card, that lost link must then be carried forward
to a managed device (switch/hub) for trap generation.
The diagram below shows a typical network configuration with good link status
using two Radiance multi-rate line cards for remote connectivity. Note that
LLCF is enabled as indicated in the diagram.
Management
Station
Management
Station
Switch/Hub
w/SNMP
Switch/Hub
w/SNMP
Multi-Rate
Line Card
LED lit = established link LED unlit = no link
Remote
Cable
Multi-Rate
Line Card
LLCF is ON LLCF is ON
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.
Link Loss Carried Forward Link Loss Carried Forward
LED lit = established link LED unlit = no link
Management
Station
Management
Station
Switch/Hub
w/SNMP
Switch/Hub
w/SNMP
Broken
Remote
Cable
Multi-Rate
Line Card
Multi-Rate
Line Card
LLCF is ON LLCF is ON
Link Loss Carried Forward
LED lit = established link LED unlit = no link
Management
Station
Management
Station
Switch/Hub
w/SNMP
Switch/Hub
w/SNMP
Broken
Cable
Remote
Cable
Multi-Rate
Line Card
Multi-Rate
Line Card
LLCF is ON LLCF is ON
NOTE: Loopback takes precedence over LLCF. If LLCF and loopback are both
enabled, LLCF functionality will be ignored for the port that is in loopback.
LLCF will remain in effect for the port that is not in loopback.
*Units are shipped with the LLCF disabled (DOWN).