User guide

12 User Guide
Management
Station
Management
Station
Switch/Hub
w/SNMP
Switch/Hub
w/SNMP
“twister”“twister”
Remote
up to 15km
LED lit = established link LED unlit = no link
Management
Station
Management
Station
Switch/Hub
w/SNMP
Switch/Hub
w/SNMP
“twister”“twister”
Broken
Remote
Cable
Trap generated Trap generated
Link Loss Carried
LED lit = established link LED unlit = no link
Link Loss Carry Forward (LLCF)
The “twister” 2131 has been designed with LLCF functionality for troubleshooting a
remote connection. The unit is shipped with the LLCF disabled.
When LLCF is enabled, the FX ports on the “twister” do not transmit a link signal until
they receive a link signal from the opposite port. For example, if LLCF is enabled and
two “twister” units are connected via a fiber cable with nothing else connected to them,
the Link LED does not illuminate. When a valid link is established, a complete connec-
tion is accomplished.
The diagram below shows a typical network configuration using “twister” media
converters for remote connectivity.
If the fiber connection breaks, or the remote device fails, the “twister” media
converters carry that link loss all the way to the switch/hub which generates a trap to
the management station. The administrator can then look at the unit to determine the
source of the loss.
IMPORTANT: When connecting a “twister” 2131 media converter to a port that
supports auto-negotiation, it is strongly recommended to fix the port setting to the
appropriate speed (100Mbps or 10Mbps) and to either full or half duplex. This
allows the media converter to sense receive link and select the active port.