User`s guide

User’s Guide 17
Auto-Recovery
A typical application of the 10/100 AutoTwister is to use it in pairs to
extend a network’s reach between two distant devices.
Switch/Hub
w/SNMP
Switch/Hub
w/SNMP
AutoTwister AutoTwister
LED lit = established link LED unlit = no link
Fiber
Cable
In this back-to-back setup, it may be desirable to see the entire link down
if any of the connecting segments fails. This means that both copper
ports must relay a no link condition to the switch/hub when any of the
cables is broken.
For proper operation in this configuration, auto-recovery must be
enabled. In the standalone AutoTwister, auto-recovery is enabled only
when all of the following switches are set as indicated:
AN1 = disabled (OFF) LLR2 = enabled (ON) LLCF = enabled (ON)
Because LLR is enabled on both units, auto-recovery is required to
prevent the two fiber ports from ending up in a deadlock situation, with
each waiting for the other to transmit first. Auto-recovery allows the
deadlock to be broken by periodically sending out pulses from the fiber
port forcing the AutoTwister to establish its fiber link if the line is intact.
The diagrams below show how the two switch/hubs are alerted to a
broken fiber cable. Notice that both LLR and LLCF must be enabled
under these conditions.
Switch/Hub
w/SNMP
Switch/Hub
w/SNMP
AutoTwister AutoTwister
LED lit = established link LED unlit = no link
Fiber
Cable
Link Loss
Carried Forward
Link Loss
Returned
Link Loss
Carried Forward
Switch/Hub
w/SNMP
Switch/Hub
w/SNMP
AutoTwister AutoTwister
LED lit = established link LED unlit = no link
Fiber
Cable
Link Loss
Carried Forward
Link Loss
Returned
Link Loss
Carried Forward