Enabling and Using FiberAlert and LinkLoss
FiberAlert and LinkLoss are configured on PC Media Converter by
adjusting a two-position switch located on the faceplate, next to the fiber
connectors. The switch for LinkLoss is labeled “LL.” The switch for
FiberAlert is labeled “FA.” Enable LinkLoss or FiberAlert by moving the
corresponding switch to the up (ON) position. Disable either (default) by
moving the switch to the down (OFF) position.
In a central site to remote site media conversion, the manufacturer
recommends you enable your PC Media Converters’ troubleshooting
features as follows: FiberAlert on the remote site only, and LinkLoss on
both the central and remote site. This will ensure that most faults can be
detected by an administrator located at the central site, no matter where
they occur on the network.
Installation Troubleshooting
• During installation, first test your fiber and twisted pair
connections with all troubleshooting features disabled. Then
enable these features, if desired, just before final installation.
This will reduce the features’ interference with testing.
• To test PC Media Converter by itself, you must have an
appropriate fiber patch cable. First, connect PC Media Converter
to the twisted pair device with a twisted pair cable. Next, loop a
single strand of fiber from the transmit port to the receive port of
your media converter. Finally, verify that you have both twisted
pair and fiber link on your PC Media Converter.
• Make sure that you are using the appropriate twisted pair cable
or have the crossover/pass-through button on the PC Media
Converter set correctly.
LED Operation
PC Media Converter features diagnostic LEDs. LED functions on PC
Media Converter TX/FX and PC Media Converter UTP/FO are:
FX RCV
Flickers amber when fiber port is receiving data
TX LNK
Glows green when a twisted pair link is established
FA
Glows green when FiberAlert is enabled
FX LNK
Glows green when a fiber link is established
TP RCV
BNC RCV
TP LNK
BNC COL
TERM
OFF ON
10 Mbps
BNC
Termination
switch
Thin
port
Coaxial
LEDs
Crossover/
pass-through
switch
Twisted Pair
port
X II
XMT
RCV
FO RCV
FO LNK
TP LNK
FA
10 Mbps
Crossover/
pass-through
switch
Twisted Pair
port
LEDs
Fiber Optic
port
X II
LL FA
FiberAlert
LinkLoss
and
switches
4
Installing modules without understanding the effects of
LinkLoss and FiberAlert can cause perfectly funcitoning units
to apear flawed or even dead!
If you are unfamiliar with LinkLoss and FiberAlert, the manufacturer
strongly encourages you to read the following information.
About Link Integrity
During normal operation, link integrity pulses are transmitted by all
point-to-point Ethernet devices. When a PC Media Converter receives
valid link pulses, it knows that the device to which it is connected is up
and sending pulses, and that the copper or fiber cable coming from that
device is intact. The appropriate “LINK” LED is lit to indicate this. The
PC Media Converter also sends out link pulses from its copper and fiber
transmitters, but normally has no way of knowing whether the cable to
the other device is intact and the link pulses are reaching the other end.
The combination of FiberAlert and LinkLoss allows this information to be
obtained, even when physical access to a remote device (and its link
integrity LED) is not available.
What Is FiberAlert?
FiberAlert lets you know when a
fault occurs on your fiber loop by
stopping data transmissions and
affecting fiber LEDs on both sides of
your network. If a media converter
is not receiving a fiberlink, FiberAlert
disables the media converter's fiber
transmitter, thus mirroring the link
status of the opposite end of the fiber. Both fiber link LEDs on either
end of the link should extinguish, alerting you to the fault.
Using FiberAlert, a local site administrator is notified of a fault and
can quickly determine where a cable fault is located without having
to go to the remote site.
NOTE: FiberAlert should only be enabled on one side of a media
conversion. Enabling it on both sides would keep both
transmitters off indefinitely.
What Is LinkLoss?
LinkLoss functions much like FiberAlert in that faults on one port are
mirrored on the other. In the case of LinkLoss, however, a fault on the
fiber port is passed to the Ethernet twisted pair port. If a PC Media
Converter is not receiving a fiber link, LinkLoss disables the transmitter
on the PC Media Converter's twisted pair port. This results in a loss of
link on the remote twisted pair device.
3
Cable Break
XMT
RCV
Remote Site
Local Site
LED OFF = Broken Link
Black Box product with
enabled —
Remote Site stops transmitting
Local Link LED is OFF indicating a break in the fiber loop
FiberAlert
X
LED
XMT
RCV
