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File:Cat 3 cable 3.jpg
A category 3 cable

Category 3 cable, commonly known as Template:No wrap or station wire, and less commonly known as VG or voice-grade<ref>Template:Cite book</ref> (as, for example, in 100BaseVG), is an unshielded twisted pair (UTP) cable used in telephone wiring. It is part of a family of standards defined jointly by the Electronic Industries Alliance (EIA) and the Telecommunications Industry Association (TIA) and published in TIA/EIA-568-B.<ref>Evolution of Cabling Standards: TIA/EIA, ISO/IEC, CENELECTemplate:Sps</ref><ref>Standards UpdateTemplate:Sps</ref>

Although designed to reliably carry data up to Template:Nowrap,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> modern data networks run at much higher speeds, and Template:No wrap or better cable is generally used for new installations.<ref>Template:Cite book</ref> Cat 3 cables may have 2, 3, 4, or more pairs.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite book</ref>

NetworkingEdit

File:Cat 3 cable 6.jpg
A category 3 cable

Template:No wrap was widely used in computer networking in the early 1990s for 10BASE-T Ethernet and, to a much lesser extent, for 100BaseVG Ethernet, Token Ring and 100BASE-T4. The original Power over Ethernet 802.3af specification supports the use of Template:No wrap cable, but the later 802.3at Type 2 high-power variation does not.<ref name="33.1.1c">IEEE 802.3at-2009, clause 33.1.1c</ref> In some use cases and for short distances, Cat 3 may be capable of carrying 100BASE-TX (2 pairs) or even 1000BASE-T (4 pairs). Such use cases include hobbyist retrofitting short home telephone Cat 3 networks for Ethernet.<ref>Gigabit over Cat3, WTFTemplate:Sps</ref><ref>CONVERTING HOME TELEPHONE WIRING TO ETHERNETTemplate:Sps</ref><ref>How to convert your telephone line to an internet line: A complete guideTemplate:Sps</ref>

Dedicated 100BASE-T4 networks, supporting Template:Nowrap over Cat 3, appear to have been a rarity as very few network interface controllers and switches were ever released. Some examples include the 3com 3C250-T4 Superstack II HUB 100, IBM 8225 Fast Ethernet Stackable Hub<ref>IBM 8225 Fast Ethernet Stackable Hub</ref> and Intel LinkBuilder FMS 100 T4.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The same applies to network interface controller cards. Bridging 100BASE-T4 with 100BASE-TX required additional network equipment.

ReplacementEdit

Starting in the mid-1990s, new structured cabling installations were often built with the higher performing Template:No wrap cable required by 100BASE-TX. Template:No wrap or Template:No wrap is now used for all modern structured cabling installations. Many large institutions have policies that any upgrade to a network using Template:No wrap must involve upgrading to Template:No wrap.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

See alsoEdit

ReferencesEdit

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External linksEdit

Template:UTP Cable Standards