Cabletron Systems 100BASE-FX, Cabling Manual

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11-1
Chapter 11
FDDI Media
This chapter details the standard media and connector types that may be used in Fiber Distributed
Data Interface (FDDI) networks.
Cabling Types
Unshielded Twisted Pair (UTP)
Unshielded Twisted Pair cabling (referred to here as UTP, but also may be termed
copper wire, 10BASE-T wire, Category 5 wire, telephone cable, or twisted pair
without shielded or unshielded qualifier) is commonly made up of four pairs of
22, 24, or 26 AWG unshielded copper solid or stranded wires. These pairs of wires
are twisted together throughout the length of the cable. These twisted pairs of
wire within the UTP cable are broken up into transmit and receive pairs. In each
pair, one wire carries the normal FDDI transmission, while its associated wire
carries a copy of the transmission that has been inverted.
Figure 11-1. UTP Cable Pair Association (2 Pairs Shown)
The twisting of associated pairs helps to reduce the interference of the other
strands of wire throughout the cable. This is due to the method of transmission
used with twisted pair transmissions.
Tx+
Tx-
Rx-
Rx+
1845n04