Twisted Pair Cables - NETGEAR ProSafe GSM7248 User Manual

User Manual for the NETGEAR 7200 Series Layer 2 Managed Switch Software Version 4
Table 10-2. Electrical Requirements of Category 5 Cable
SPECIFICATIONS
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. Auto
Uplink technology automatically senses which connection, MDI or MDI-X, is needed and makes
the right connection.
Figure 10-1 illustrates straight-through twisted pair cable.
Figure 10-1: Straight-Through Twisted-Pair Cable
Cabling Guidelines
CATEGORY 5 CABLE REQUIREMENTS
Four
100 ± 15%
5.6 nF per 100 m
at 4 MHz: 8.2
at 31 MHz: 11.7
at 100 MHz: 22.0
at 16 MHz: 44
at 31 MHz: 39
at 100 MHz: 32
202-10102-01, May 2005
A-3