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NOTE
STP Cable Quality
STP cable is available in a series of construction and quality styles, known as
Types. FDDI TP-PMD applications require STP cables that meet the quality and
construction specifications of Type 1 or Type 2 STP cable, as detailed in the
sections that follow.
Type 1
Type 1 STP consists of two pairs of solid 22 AWG copper strands. Each strand,
approximately 0.02 inch thick, is surrounded by a layer of insulation. The
characteristics of the insulation is determined by the fire resistance construction of
the cable (plenum cable is thicker and made with slightly different material than
normal PVC cabling).
The individual wires are twisted into pairs. The pairs that are formed by this
twisting are then surrounded by a mylar foil shield. These shielded pairs are then
laid alongside one another in an overall braided metal shield. The shield
containing the twisted pairs is then surrounded by a tight outer covering. Type 1
STP is heavy and rather inflexible, but provides excellent resistance to
interference and noise due to its construction characteristics. Type 1 STP is most
commonly used as a facility cabling, while more flexible cabling is used for
jumper cables and patch panel connections.
Cabling Types
Table 11-1. STP Cable Wire Identifications
Cable Color
Black
Red
Green
Orange
As STP cabling provides only two pairs of wire, it may only be
used for Single Attached Station connections from FDDI
concentrators to stations (M ports to S ports).
Application
TX -
RX +
RX -
TX +
FDDI Media
11-7
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