Network Cables User Manual

Gigabit “twister” and SONET “twister” 7
NOTE: The ON/OFF positions are not the same on all units.
By default, all DIP switches are disabled.
Link Loss Return (LLR) Switch
The Metrobility “twister” incorporates Link Loss Return functionality as an
aid in troubleshooting remote fiber connections. When LLR is enabled on a
port, loss of the receive (RX) link at the port disables the transmit (TX) link
on the same port. LLR is set independently on each fiber port.
LLR1 enables/disables Link Loss Return on Port 1, and LLR2 enables/
disables it on Port 2. To enable Link Loss Return, set the LLR switch to the
ON position. Set the switch OFF to disable the function. The unit is shipped
with LLR disabled. For more information, refer to Link Loss Return in the
User Guide section of this manual.
Link Loss Carry Forward (LLCF) Switch
On the fiber-to-fiber repeaters, Link Loss Carry Forward is provided as an
additional aid for troubleshooting remote connections. If LLCF is enabled
and the “twister” loses link on one of its receive ports, LLCF inhibits the
transmit link out the opposite port.
For example, if LLCF is enabled and the “twister” fails to detect link on
Port 2, the “twister” will not transmit link pulses out of Port 1. In doing
this, LLCF provides a way to extend the link loss indication beyond a
single segment.
PWR
DC INPUT/5VDC
DIP switches (2152 TX-FX)
LLCF LLR1 LLR2
CLCF
LLR1
LLR2
DIP switches (2152 FX-FX)
LLCF LLR2
or
ON
OFF
OFF
ON
ON
OFF
LLR1
DIP switches (all others)
LLCF LLR2
or
OFF
ON
SM
PWR
1000BASE-LX
™
“twister” 2152
MM
TX
RX
1000BASE-SX
LINK
LINK
Port 2 Port 1
TX RX