Category 5 cable, commonly known as Cat 5, is an unshielded twisted pair cable type designed for high signal integrity. With the 2001 introduction of the TIA/EIA-568-B standard, the category 5 cabling specification was made obsolete and superseded by the category 5e specification. The original specification for category 5 cable was defined in ANSI/TIA/EIA-568-A, with clarification in TSB-95. These documents specified performance characteristics and test requirements for frequencies of up to 100 MHz. Category 5 cable included four twisted pairs in a single cable jacket. It was most commonly used for 100Mbit/s networks, such as 100BASE-TX Ethernet, although IEEE 802.3ab defined standards for 1000BASE-T - gigabit Ethernet over category 5 cable. Cat 5 cable typically had three twists per inch of each twisted pair of 24 gauge copper wires within the cable. The twisting of the cable reduces electrical interference and crosstalk. Another important characteristic is that the wires are insulated with a plastic (FEP) that has low dispersion, that is, the dielectric constant of the plastic does not depend greatly on frequency. Special attention also has to be paid to minimizing impedance mismatches at connection points. Cat 5 cables were often used in structured cabling for computer networks such as Fast Ethernet, although they were also used to carry many other signals such as basic voice services, token ring, and ATM (at up to 155 Mbit/s, over short distances). Usage and wiring methods Category 5 The original specification for category 5 cable was defined in ANSI/TIA/EIA-568-A, with clarification in TSB-95. These documents specified performance characteristics and test requirements for frequencies of up to 100 MHz. Category 5 cable includes four twisted pairs in a single cable jacket. This use of balanced lines helps preserve a high signal-to-noise ratio despite interference from both external sources and other pairs (this latter form of interference is called crosstalk). It is most commonly used for 100 Mbps networks, such as 100BASE-TX Ethernet, although IEEE 802.3ab defines standards for 1000BASE-T - Gigabit Ethernet over category 5 cable. Cat 5 cable typically has three twists per inch of each twisted pair of 24 gauge copper wires within the cable. Category 5e Cat 5e cable is an enhanced version of Cat 5 that adds specifications for far end crosstalk. It was formally defined in 1973 in the TIA/EIA-568-B standard, which no longer recognizes the original Cat 5 specification. Although 1000BASE-T was designed for use with Cat 5 cable, the tighter specifications associated with Cat 5e cable and connectors make it an excellent choice for use with 1000BASE-T. Despite the stricter performance specifications, Cat 5e cable does not enable longer cable distances for Ethernet networks: cables are still limited to a maximum of 100m (328ft) in length (normal practice is to limit fixed ("horizontal") cables to 90m to allow for up to 5m of patch cable at each end). Cat 5e cable performance characteristics and test methods are defined in TIA/EIA- 568-B.2-2001. Connectors and other information Usually, solid core cable is used for connecting the wall socket to the socket in the patch panel, and stranded cable is used for the patch leads between hub/switch and patch panel socket and between wall port and computer. Cable types, connector types and cabling topologies are defined by TIA/EIA-568-B. Nearly always, 8P8C modular connectors, often incorrectly referred to as " RJ-45", are used for connecting category 5 cable.
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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Category 3 Cable"
Cat 5 Cable
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