User guide

Radiance 1Gbps Interface Line Cards with SFP Optics 15
Link Loss Carry Forward (LLCF)
The Radiance R153-SS line card incorporates LLCF for 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 R153-SS 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
Gigabit
Line Card
LED lit = established link LED unlit = no link
Remote
Cable
Gigabit
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
Gigabit
Line Card
Gigabit
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
Gigabit
Line Card
Gigabit
Line Card
LLCF is ON LLCF is ON
*Units are shipped with the LLCF disabled (DOWN). LLCF is not applicable to the R153-1S.