Far End Fault (Fef) - METRObility Optical Systems Delta Class Installation And User Manual

Far End Fault (FEF)

The Metrobility "twister" is designed with Far End Fault
identify the loss of link in the remote unit's fiber receiver. FEF is not
applicable to the copper port.
Setting FEF on the fiber optic port enables two operations:
1. It allows the fiber
receiver
fails to detect a valid link.
2. It enables the port to read the FEF alarm, so it can activate its FEF
LED.
To function properly, the FEF setting on both the local and
IMPORTANT:
the remote "twister" must be the same.
The diagram below shows a typical network configuration with good link
status using two "twister" units with FEF enabled.
Switch/Hub
PC
LK LED green = established link
If one of the optical conductors is bad (as shown in the diagram box
below), "twister" B will send a FEF alarm to its link partner on "twister" A.
"twister" A will report the condition through its amber FEF LED and unlit
LK LED.
Switch/Hub
PC
LK LED green = established link
In the example described above, if FEF is disabled on "twister" B, the
FEF alarm will not be transmitted to "twister" A. If FEF is disabled on
"twister" A, it will not be able to read the FEF alarm and its link (LK) LED
will remain green.
*Units are shipped with the FEF function disabled.
16 Metrobility 100Mbps Delta Class "twister"
transmitter
twister
w/SNMP
A
FEF is ON
Copper
twister
w/SNMP
A
FEF is ON
Copper
to issue a FEF alarm when the fiber
twister
B
FEF is ON
Fiber
Cable
LK LED unlit = no link
twister
B
FEF is ON
Broken
Fiber
Conductor
FEF Alarm Sent
LK LED unlit = no link
*
functionality to
Switch/Hub Remote
w/SNMP Station
Copper
LK LED amber= FEF detected
Switch/Hub Remote
w/SNMP Station
Copper
LK LED amber= FEF detected