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Chapter 11—Networking
Ethernet connector types remain in wide use. When a network
interface card has more than one connector type, you might need
to use the card’s setup program to select which connector to use.
Wire Pairing for Twisted-Pair
Cabling
For large, multi-office installations, network cables are usually built
from bulk cable stock and connectors. Because the twisted-pair
cabling has eight wires, many pairings are possible. If you are
adding cable to an existing installation, you should match the wire
pairings already in use. However, the most popular wiring standard
is the AT&T 258A standard detailed in Table 11.9. You can buy prebuilt
cabling that matches this standard or build your own.
Table 11.9 RJ-45 Connector Wire Pairing and Placement AT&T
258A Standard
Wire Pairing Wire Connected to Pin # Pair Used For
White/blue and blue White/blue - #5 Not used1 Blue - #4
White/orange and orange White/orange - #1
Orange - #2
Transmit
White/green and green White/green - #3
Green - #6
Receive
White/brown - brown White/brown - #7 Not used1 Brown - #8
1. This pair is not used with 10BASE-T or Fast Ethernet 100BASE-TX, but all four pairs are used
with Fast Ethernet 100BASE-T4 and with Gigabit Ethernet 1000BASE-TX standards.
Thus, a completed cable that follows the AT&T 268A (also called
the EIA/TIA 568B) standard should look similar to the following
when viewed from the flat side of the RJ-45 connector (from left to
right): orange/white, orange, green/white, blue, blue/white, green,
brown/white, brown.
Making Your Own UTP Cables
You will need the following tools and supplies to build your own
Ethernet cables:
• UTP cable (Category 5 or better)
• RJ-45 connectors
• Wire stripper
• RJ-45 crimping tool