IBM 847620U - Netfinity 3000 - 20U, Hardware Maintenance Manual, Page: 62 / 270

Table 1 on page 54 describes the specifications for UTP
cables used in 10BASE-T and 100BASE-TX link segments.
Cables for these link segments must be certified as
EIA/TIA-568 Category 5.
Note
AWG = American Wire Gauge
EIA = Electronics Industries Association
STP = shielded twisted pair
TIA = Telecommunications Industries Association
The following figure illustrates the RJ-45 connector.
10BASE-T or 100 BASE-TX
UTP Cable
RJ-45 Modular Plug Connector
1
2
3
Pins 6
The following figure illustrates the wiring in straight-through
cables.
Twisted
Pair
1
2
3
6
4, 5, 7, 8
RJ-45 Modular Connector
Pin
1
1
2
2
3, 4
10BASE-T / 100 BASE-TX
1
2
3
6
4, 5, 7, 8
Pin
TD+
TD
RD+
RD
RJ-45 Modular Connector
(Not used)
TD+
TD
RD+
RD
(Not used)
Signal
Name Signal
Name
Relative to the device connected to the adapter
Table 1. Cabling Specifications for 10BASE-T and
100BASE-TX Link Segments
Characteristic Specification ñ
Cable type UTP cable with two twisted pairs
of 22, 24, or 26 AWG
ò
wire
Nominal impedance 100 Ohms
Velocity of propagation 0.585 c
ó
Maximum attenuation
Ÿ
For 10BASE-T: 8 to 10 dB
per 100 m at 10 MHz
Ÿ
For 100BASE-TX: 67 dB
per 305 m at 100 MHz
Notes:
1. Cables that have been certified as EIA/TIA-568 Category 5 meet all
10BASE-T and 100BASE-TX specifications. An EIA/TIA-568
Category 5 cable must be used for 10BASE-T and 100BASE-TX.
2. The cable can contain two to four twisted pairs, but only two of the
pairs will be used by the 10BASE-T or 100BASE-TX network.
3. The c represents the velocity of light traveling in a vacuum, which
is 300 000 km/sec (186 400 mi/sec).
54
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