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Installation Guide for the Model SW108 Ethernet Switch
Table C-1 lists the electrical requirements of the Category 3, 4, and 5 cables.
Table C-1.
Electrical requirements of Category 3, 4, and 5 cables
Specification
Number of pairs
Impedance
Mutual capacitance at 1 KHz
Maximum attenuation
(dB per 100 m, at 20 C)
NEXT loss (dB minimum)
Twisted Pair Cables
For two devices to communicate, the transmitter of each device must be connected to the
receiver of the other device. The crossover function is usually implemented internally as
part of the circuitry in the device. Computers and workstation adapter cards are usually
media-dependent interface ports, called MDI or uplink ports. Most repeaters and switch
ports are configured as media-dependent interfaces with built-in crossover ports, called
MDI-X or normal ports.
C-2
Category 3
Four
100
15%
6.6 nF per 100 m
at 4 MHz: 5.6
at 10 MHz: 9.8
at 16 MHz: 13.1
at 4 MHz: 32
at 10 MHz: 26
at 16 MHz: 23
Category 4
Four
100
15%
5.6 nF per 100 m
at 4 MHz: 4.3
at 10 MHz: 7.2
at 16 MHz: 8.9
at 4 MHz: 47
at 10 MHz: 41
at 16 MHz: 38
Category 5
Two or Four
100
15%
5.6 nF per 100 m
at 16 MHz: 8.2
at 31 MHz: 11.7
at 100 MHz: 22
at 16 MHz: 44
at 31 MHz: 39
at 100 MHz: 32
Cabling Guidelines
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