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KEY TEST PARAMETERS
The TIA 568-3.D cabling standard includes instructions on how to maintain polarity for duplex fiber installations, ensuring that
“transmit” always goes to “receive”. Fiber OWL 7 series testers keep track of FIBER PAIR GEOMETRY: 1) to maintain polarity
during testing by displaying helpful connection diagrams; and 2) to keep track of the direction of the test for each fiber under test.
TIA 568-3.D Annex C defines two methods for maintaining proper duplex polarity: consecutive-fiber positioning (STRAIGHT) and
reverse-pair positioning (CROSSED). The diagrams below are adapted from the standard.
Consecutive-fiber positioning.
Fibers are arranged consecutively (e.g. 1-n) from left to right on both ends of the link. Behind the
patch panel, all connectors are installed “keys up”.
Reverse-pair positioning.
Fibers are arranged consecutively (e.g. 1-n) on one end of the link, but each duplex pair is reversed on
the other end (i.e. 2,1 4,3 6,5 etc.). Behind the patch panel, the consecutive-fiber side connectors are installed “keys up” while
the reverse-pair side connectors are installed “keys down”.
FIBER PAIR GEOMETRY
1
n-1 n
4
3
2
Fiber
number
. . .
Consecutive-fiber order
1
n-1 n
4
3
2
Fiber
number
. . .
Consecutive-fiber order
Cable
1
n-1 n
4
3
2
Fiber
number
. . .
Consecutive-fiber order
Cable
2
n
3
4
1
Fiber
number
. . .
Reverse-pair order
n-1
