Cabletron Systems 100BASE-FX, Cabling Manual

Page: 126 / 192

FDDI Media
11-12 Connector Types
Figure 11-7. EIA/TIA 568A Pinout and Pair Association
The EIA/TIA 568 B specification reverses the arrangement of Pair 1 and Pair 2,
but does not change the association of pairs within the cable. The Universal
Service Order Code, or USOC, a standard often used for older building telephone
wiring, uses a different pair association than EIA/TIA 568A. The use of either of
these alternate cable construction standards will lead to error conditions in FDDI
TP-PMD networks.
STP
Shielded RJ45
The shielded RJ45 cable used with STP cable is identical in shape to the standard
RJ45 cable used in other network applications such as Ethernet and Token Ring.
The difference between the shielded RJ45 and the standard RJ45 is the addition of
a metal shielding ground to the plastic housing of the RJ45 connector. This shield
is connected to the braided outermost shield of the STP cable.
The connector itself is a rectangular keyed connector with a locking clip. The RJ45
connector may only be inserted into an RJ45 port in its proper alignment, and,
when inserted, will lock into place. Due to the lighter construction characteristics
of the RJ45 connector in comparison with the other STP cable connectors, care
should be taken to ensure that the strain placed on an RJ45 connection is
minimized through proper use of cable management hardware.
The shielded RJ45 cable is made up of the plastic and metal outer housing and
locking clip. Within the housing, a series of contact blades are lined up next to one
another to provide contact points for the pins of the RJ45 port. The contact blades
themselves are square-shaped, flat on three sides and with a set of two or three
triangular teeth on one side. The teeth of the connector are at the bottom of the
blades to pierce the individual wires of the STP cable when the connector is
crimped shut.
W-OR BL W-BL GR OR W-BR W-GR BR
Pair 1
Pair 2
Pair 4
Pair 3
1845n16