Cabletron Systems 100BASE-FX, Cabling Manual

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Token Ring Media
9-6 Cabling Types
While UTP cables are usually built to provide four pairs of wire, IEEE 802.5
standards only require the use of two pairs, referred to as Pair 1 and Pair 2 (Pair 1
and Pair 3 of the EIA/TIA 568A specification). Pair 2 of the connector is the
transmit pair and Pair 1 of the connector is the receive pair. This organization of
wires at the connector is referred to as a pinout. Pinouts will be discussed in
greater detail in the Connector Types section of this chapter.
UTP cabling is produced in a number of overall quality levels, called Categories.
The requirements of networking limit UTP cabling for Token Ring to Categories 3,
4, or 5. Any of these cable Categories can be used in a Token Ring installation,
provided that the requisite IEEE 802.5 specifications regarding the cables are met.
Table 9-2. IEEE 802.5 Wire Use
Wire Color USOC Pair
Token Ring Signal Use
568A 568B
White/Blue (W-BL)
Pair 1
Pins 3 and 4
TX+ RX+
Blue (BL) TX- RX-
White/Orange (W-OR)
Pair 2
Pins 2 and 5
RX+ TX+
Orange (OR) RX- TX-
White/Green (W-GR)
Pair 3
Pins 1 and 6
Not Used
Green (GR)
White/Brown (W-BR)
Pair 4
Pins 7 and 8
Not Used
Brown (BR)
NOTE
Do not split pairs in a twisted pair installation. While you may
consider combining your voice and data cabling into one piece
of horizontal facility cabling, the crosstalk and interference
produced by this practice greatly reduces the viability of the
cable for either application. The use of the pairs of cabling in
this fashion can also prevent the future usage of advanced
networking technologies that require the use of all four pairs in
a twisted pair cable.