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Appendix A
Data Cabling Techniques
Depending on the medium you choose, there are certain wiring practices
you should follow to ensure the reliability of communication throughout
the network. The AT-3600 Series hubs comply with IEEE standards for
802.3 Carrier Sense Multiple Access with Collision Detect (CSMA/CD)
Ethernet. The following sections detail cabling techniques and port
specifications for IEEE 802.3 media. For comprehensive treatment of
these topics, refer to the original IEEE specification.
10BASE-T
The maximum length for 10BASE-T UTP segments is 100 meters (328 ft.).
UTP Wiring
Specifications
10BASE-T requires UTP wiring capable of supporting 10 megabit data
rates. A serious problem exists concerning identification of modular cable.
There are various grades of voice-quality and data-quality cables
available. These can appear to be similar externally, although their
high-speed data transmission characteristics are radically different.
The identification problem is exaggerated because some suppliers have
sold data-quality cables manufactured with voice-quality cabling.
If any voice-quality cabling is used in a 10BASE-T network system, data
movement is slow, collision-prone or non-existent. To confuse the issue, the
Link indicator on the interface will usually indicate a valid link in such a
case.
For the foregoing reasons, it is essential that all cabling used with the
10BASE-T connections be Level 3, 4 or 5. The wire should be 22 to 26
American Wire Gauge (AWG), 100
Ω
impedance with 3 to 8 twists per foot.
Following these guidelines will help maintain 10 megabit data integrity
throughout the wiring system.
As a rule of thumb, if a cable type is flat, it is untwisted and will cause
problems. If a cable is more or less round in section, it will work. “Silver
Satin” flat cable is out of specification and should not be used.
