User guide

16 User Guide
Link Loss Carry Forward (LLCF)
The R752-SS redundant interface line card has been designed with LLCF
functionality to aid in troubleshooting remote connections.
When LLCF is enabled
*
and the R752-SS stops receiving link signals on a port,
it stops the transmission of link signals on the other port of the line card. For
example, if LLCF is enabled and two R752-SS redundant line cards are con-
nected at the PRIMARY port with nothing else connected to them, their Link
LEDs will not be lit. When a valid link is established by connecting to the
MAIN port, a complete connection is accomplished.
The diagram below shows a typical network configuration using R752-SS
redundant line cards for remote connectivity:
Management
Station
Management
Station
Switch/Hub
w/SNMP
Switch/Hub
w/SNMP
R752-SS
Redundant
Line Card
Remote
up to 100 km
LED lit = established link LED unlit = no link
R752-SS
Redundant
Line Card
If the remote cable breaks, or the remote device fails, the cards carry that link
loss all the way to the switch/hub which generates a trap to the management
station. The network administrator can then look at the card to determine the
source of the loss.
Management
Station
Management
Station
Switch/Hub
w/SNMP
Switch/Hub
w/SNMP
R752-SS
Redundant
Line Card
Broken
Remote
Cable
Link Loss Carried
LED lit = established link LED unlit = no link
R752-SS
Redundant
Line Card
IMPORTANT: When connecting a line card to a port that supports auto-
negotiation, it is strongly recommended to fix the port setting to 1000Mbps at
either full or half duplex. This allows the card to sense receive links and select
the active port.
* The card is shipped with LLCF disabled.