IBM Netfinity 3500, Руководство пользователя

Страница: 236 / 294

Ÿ
If the port on the repeater is not a crossover port (also known as
an MDI port), use a UTP cable that is wired as a crossover
cable.
Do not use telephone extension cables to connect the server to a
repeater. The wire pairs in those cables are not twisted, and the
cables do not meet other requirements for use in a 10BASE-T or
100BASE-TX network. You can identify telephone extension cables
by their flat and thin appearance. UTP cables are rounder and
thicker than telephone extension cables.
Table 17 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.
ñ
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.
ò
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.
ó
The c represents the velocity of light traveling in a vacuum,
which is 300 000 km/sec (186 400 mi/sec).
Table 17. 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
218
Netfinity 3500 User's Handbook