Information Technology Reference
In-Depth Information
Cabling for 10/100BaseT is simply a wiring star of hub and nodes. Generally,
a hub is located centrally, perhaps in a TR, and station cables are run to each work-
station location. The cables may be terminated in a patch panel or on a punchdown
block adjacent to the hub. A patch cord or octopus (fan-out) cable connects each
station cable to a hub port. These terminations are covered in detail in Part Two.
At the workstation location, station cables are normally terminated in a wall
jack and a user cord connected to the workstation. The wiring can be the standard
2-pair 10/100BaseT wiring shown in Fig. 2.4. However, the more robust 4-pair
wiring pattern of TIA/EIA-568-C offers effectively the same connections. A connec-
tor jack's internal wiring may present some confusing variations in wire colors and
numbering; some of these variations are shown in Fig. 2.5. Note that the wiring col-
ors may be completely different from those of the station cable and the plates some-
times have numeric markings that do not correspond to the pin numbering of the
jack itself. Fortunately, 10/100BaseT has the ability to sense misconnections, and
the hub status light for the port is a good diagnostic tool. Inexpensive modular test
indicators are also available to help you make this connection.
All wiring in 10/100BaseT is straight through (pin 1 to pin 1, pin 2 to pin 2,
and so on). Be careful to use only adapters, patch cords, adapter cables, and acces-
sories that are wired this way. Many similar cables and adapters that are intended
for telephone use are wired “crossover,” which means pin 1 to pin 8, etc. In addi-
tion, all 10/100BaseT wiring is
twisted pair
. Avoid using the flat telephone wire,
such as silver satin, that is sometimes available with 8-pin modular connectors.
Each leg of a 10/100BaseT network is limited to 100 m (328 ft). Of this 100
m, 90 m typically may be station wire and an additional 10 m may be the total for
the patch cord, cross-connect (if any), and workstation cable (user cord). Cable,
1
Transmit Data
Transmit Data
10BaseT
Medium-dependent
interface
(x = unused)
2
3
Receive Data
x
4
5
x
Receive Data
6
7
x
8
x
8-pin Modular jack
(Front view)
FIGURE 2.4
10BaseT interface wiring pattern (identical to the 100BaseT pattern).
