METRObility Optical Systems RADIANCE R231-1Y - Manual (Page 17)

Radiance Access Line Cards 17
Link Loss Carry Forward (LLCF) *
The access line cards incorporate an LLCF function for troubleshooting a remote
connection. When LLCF is enabled, the ports do not transmit a link signal until
they receive a link signal from the opposite port.
The diagram below shows a typical network configuration with a good link
status using access line cards for remote connectivity. Note that LLCF is enabled
as indicated in the diagram.
Management
Station
Switch/Hub
w/SNMP
Customer
Site
Access
Line Card
Access
Line Card
LED lit = established link LED unlit = no link
LLCF is ON LLCF is ON
TX TX FX
Remote
Cable
If the fiber connection breaks, the card carries that link loss forward to the
switch/hub which generates a trap to the management station. The administrator
can then determine the source of the problem.
Link Loss Carried Forward
LED lit = established link LED unlit = no link
Management
Station
Switch/Hub
w/SNMP
Customer
Site
Access
Line Card
Access
Line Card
LLCF is ON LLCF is ON
TX TX Broken
FX Remote
Cable
Link Loss Carried Forward
LED lit = established link LED unlit = no link
Management
Station
Switch/Hub
w/SNMP
Customer
Site
Access
Line Card
Access
Line Card
LLCF is ON LLCF is ON
TX Broken
TX
Cable
FX
Remote
Cable
Important: When connecting a line card with LLCF enabled to an auto-
negotiating device, force both sides of the configuration to 100Mbps and either
full or half duplex. This allows the card to immediately see link pulses and start
passing data.
* Cards are shipped with LLCF disabled (OFF).