Description of Twisted-Pair Category Types (151713)
The information in this article applies to:
- Microsoft Windows NT Workstation 3.5
- Microsoft Windows NT Workstation 3.51
- Microsoft Windows NT Server 3.5
- Microsoft Windows NT Server 3.51
- Microsoft LAN Manager 2.2c
- Microsoft Windows for Workgroups 3.11
- Microsoft TCP/IP-32 for Windows for Workgroups 3.11
- Microsoft TCP/IP-32 for Windows for Workgroups 3.11a
- Microsoft TCP/IP-32 for Windows for Workgroups 3.11b
- Microsoft Windows 95
- Microsoft Network Client for MS-DOS 3.0
This article was previously published under Q151713 SUMMARY
This article describes twisted-pair cabling and its role in the
Electronic Industries Association/Telecommunications Industries
Association (EIA/TIA)568 Commercial Building Wiring Standard
specification.
MORE INFORMATION
Twisted-pair consists of copper core wires surrounded by an insulator.
Two wires are twisted together to form a pair, and the pair forms
the circuit that can transmit data. A cable is a bundle of one or
more twisted pairs surrounded by another insulator and twisted
together. Unshielded twisted-pair (UTP) is common in a telephone
network. Shielded twisted-pair (STP) provides protection against
external crosstalk by using braided metal shielding. The twisting
prevents interference problems, but must be maintained all the way
to the connection points.
Categories of Twisted-Pair
The EIA/TIA 568 specification standardizes the installation of
wiring. It applies to all UTP wiring schemes that work with Ethernet
10Base-T, token-ring, Private Branch Exchange (PBX), Integrated
Services Digital Network (ISDN), and Twisted Pair-Physical Media
Dependent (TP-PMD) networks. EIA/TIA 568 defines the following
cable categories:
Category 1: Unshielded twisted-pair (UTP) cable that is suited
for voice but not data. Most telephone cable installed before
1983 is Category 1 cable. Not widely used anymore.
Category 2: UTP cable certified for data transmissions up to
4 Mbits/second. Similar to IBM Cabling System Type 3 and
is commonly installed as modern telephone cable. This cable
has four twisted pairs.
Category 3: UTP that supports 10-Mbits/sec transmission rates
and is required for token-ring (4 Mbits/sec) and 10-Mbits/sec
Ethernet 10Base-T. The cable must have four pairs and three
twists per foot.
Category 4: UTP certified for 16 Mbits/sec transmission rates
and is the lowest grade acceptable for 16 Mbits/sec token-ring.
The cable has four pairs.
Category 5: Defines 100-ohm, four-wire twisted-pair UTP copper
cable that can transmit data at 100 Mbits/sec to support
technologies such as Fast Ethernet and Asynchronous Transfer
Mode (ATM), if installed according to specifications. The
cable is low-capacitance and exhibits low crosstalk. However,
all components must be Category 5 compliant; therefore, older
modular connectors and jacks are not suitable for Category 5
installations.
REFERENCES
Sheldon, Tom. "LAN Times Encyclopedia of Networking." Berkeley:
Osborne McGraw-Hill, 1994.
| Modification Type: | Minor | Last Reviewed: | 7/16/2004 |
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| Keywords: | kbnetwork KB151713 |
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