Category 6 cable
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Category 6 cable, commonly referred to as Cat.-6, is a cable standard for Gigabit Ethernet and other network protocols that are backward compatible with the Category 5/5e and Category 3 cable standards. Compared with Cat.-5 and Cat.-5e, Cat.-6 features more stringent specifications for crosstalk and system noise. The cable standard provides performance of up to 250 MHz and is suitable for 10BASE-T, 100BASE-TX (Fast Ethernet), 1000BASE-T/1000BASE-TX (Gigabit Ethernet) and 10GBASE-T (10-Gigabit Ethernet). Category 6 cable has a reduced maximum length when used for 10GBASE-T; Category 6a cable, or Augmented Category 6, is characterized to 500 MHz and has improved alien crosstalk characteristics, allowing 10GBASE-T to be run for the same distance as previous protocols. Category 6 cable can be identified by the printing on the side of the cable sheath.[1]
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[edit] Category 6
Like most earlier cables, Category 6 cable contains four twisted wire pairs. Although it is sometimes made with 23 AWG wire, the increase in performance with Cat.-6 comes mainly from better insulation; 22 to 24 AWG copper is allowed if the ANSI/TIA-568-B.2-1 performance specifications are met. Cat.-6 patch cables are normally terminated in 8P8C (often incorrectly called RJ-45) modular connectors. Attenuation, NEXT (near end crosstalk), and PSNEXT (power sum NEXT) in Cat.-6 cable and connectors are all significantly lower than Cat.-5/5e, which also uses 24 AWG wire.
The heavier insulation in some Cat.-6 cables makes them too thick to attach to 8P8C connectors without a special modular piece, resulting in a technically out-of-compliance assembly.
Connectors use either T568A or T568B pin assignments; the choice is arbitrary provided both ends of a cable are the same. Both schemes use straight-through wiring (pin 1 to 1, pin 2 to 2, etc) and the same pairing (pins 1&2, 3&6, 4&5, 7&8). Only the wire colors differ, which is of no concern outside the cable. This makes T568A and T568B patch cords interchangeable, with T568B being the most common.
If Cat.-6 rated patch cables, jacks, and connectors are not used with Cat.-6 wiring, overall performance is degraded to that of the cable or connector. Because the conductor sizes are generally the same, Cat.-6 jacks may also be used with Cat.-5e cable.
Because all 1000BASE-T (gigabit Ethernet) equipment and nearly all new 10BASE-T and 100BASE-TX equipment supports automatic crossover (auto-MDIX), Cat.-6 crossover cables are rare.[clarification needed] Crossover cables are needed only between 10/100 Mb/s hosts or switches where some endpoint does not support auto-MDIX; otherwise Cat.-5 is sufficient for these slower speeds.
| Pin | Pair | Wire | Color |
|---|---|---|---|
| 1 | 3 | 1 |  white/green |
| 2 | 3 | 2 |  green |
| 3 | 2 | 1 |  white/orange |
| 4 | 1 | 2 |  blue |
| 5 | 1 | 1 |  white/blue |
| 6 | 2 | 2 |  orange |
| 7 | 4 | 1 |  white/brown |
| 8 | 4 | 2 |  brown |
| Pin | Pair | Wire | Color |
|---|---|---|---|
| 1 | 2 | 1 | white/orange |
| 2 | 2 | 2 | orange |
| 3 | 3 | 1 | white/green |
| 4 | 1 | 2 | blue |
| 5 | 1 | 1 | white/blue |
| 6 | 3 | 2 | green |
| 7 | 4 | 1 | white/brown |
| 8 | 4 | 2 | brown |
| Pin | Pair | Wire | Color |
|---|---|---|---|
| 1 | 4 | 1 | white/brown |
| 2 | 3 | 1 | white/green |
| 3 | 2 | 1 | white/orange |
| 4 | 1 | 2 | blue |
| 5 | 1 | 1 | white/blue |
| 6 | 2 | 2 | orange |
| 7 | 3 | 2 | green |
| 8 | 4 | 2 | brown |
[edit] Category 6a
The latest standard from the TIA for enhanced performance standards for twisted pair cable systems was defined in February 2008 in ANSI/TIA/EIA-568-B.2-10. Category 6a (or Augmented Category 6) is defined at frequencies up to 500 MHz—twice that of Cat. 6.
Category 6a performs at improved specifications, particularly in the area of alien crosstalk as compared to Cat.-6 UTP which exhibited high alien noise in high frequencies.
The global cabling standard ISO/IEC 11801 will soon be extended by the addition of amendment 2. This amendment defines new specifications for Cat. 6A components and Class EA permanent links. These new global Cat. 6A/Class EA specifications require a new generation of connecting hardware offering far superior performance compared to the existing products which are based on the American TIA standard.
The most important point is a performance difference between ISO/IEC and EIA/TIA component specifications for the NEXT transmission parameter. At a frequency of 500 MHz, an ISO/IEC Cat. 6A connector performs 3 dB better than a Cat. 6A connector that conforms with the EIA/TIA specification. 3 dB equals 100% increase of near-end crosstalk noise reduction when measured in absolute magnitudes.[2]
TIA comp. Cat. 6A ≠ ISO/IEC Cat. 6 A comp.3[3]
[edit] Maximum length
The maximum allowed length of a Cat.-6 cable is 100 meters (330 ft) when used for 10/100/1000BASE-T. This consists of 90 meters (300 ft) of solid "horizontal" cabling between the patch panel and the wall jack, plus 10 meters (33 ft) of stranded patch cable between each jack and the attached device. Since stranded cable has higher attenuation than solid cable, exceeding 10 metres of patch cabling will reduce the permissible length of horizontal cable.
When used for 10GBASE-T, Cat.-6 cable's maximum length is 55 meters (180 ft) in a favourable alien crosstalk environment, but only 37 meters (121 ft) in a hostile alien crosstalk environment such as when many cables are bundled together. 10GBASE-T runs of up to 100 meters (330 ft) are permissible using Cat.-6a.
[edit] Installation caveats
Category 6 and 6a cable must be properly installed and terminated to meet specifications. Incorrect installation practices include kinking the cable or bending it with too tight a radius. Incorrect termination practices include untwisting the wire pairs or stripping the outer jacket back too far.
All shielded cables must be grounded at both ends in order for the shield to offer full effectiveness.[4] Unshielded Category 6a cable does not have this limitation, but has a larger diameter.
To ensure that an installation will meet the requirements for the network protocol it will be used for, a new installation is usually certified using a so-called cable certifier, validator or qualification tester.
[edit] See also
[edit] References
- ^ Ethernet Cable Identification and Use
- ^ Details about TIA and ISO Cat 6a
- ^ Cabling: The Complete Guide to Network Wiring, 3rd Edition
- ^ TIA/EIA 568C, ISO 11801 and BICSI TDMM
[edit] External links
- "10 Gb/s Over Copper: Horizontal Cabling Choices". The Siemon Company. 2006-01-10. http://www.siemon.com/us/white_papers/06-01-10_10G-horizontal-cabling-choices.asp. Information on cable construction and alien crosstalk mitigation.
- Schmidt, John (March/April 2007). "Determining the Right Media" (PDF). BICSI News 28 (2). http://www.adc.com/us/en/productsandservices/truenet/media/Determining_the_Right_Media.pdf. Information on TIA TSB-155 37m versus IEEE 55m limitations.
- "What are CAT6 Cables?". KSM Limited. http://www.cat6cables.co.uk/index.html.
- "How to Make an Ethernet Cat5e/Cat6 Cable". Cable & Wireless Technologies, Inc.. 2009-10-14. http://discountlowvoltage.blogspot.com/2009/10/how-to-make-ethernet-cat5e-cable.html.
- "How to Terminate Cat6a Shielded Keystone Jacks". Cable & Wireless Technologies, Inc.. 2009-12-09. http://discountlowvoltage.blogspot.com/2009/12/how-to-terminate-cat6a-shielded.html.
- "How Category 6 Cable is Made". Cable & Wireless Technologies, Inc.. 2009-11-05. http://discountlowvoltage.blogspot.com/2009/11/how-low-voltage-cable-is-made-cat5e.html.
- "How to Build Cat 6 Patch Cables - Step by Step with Detailed Photos". ComputerCableStore.com. 2007-10-11. http://www.computercablestore.com/cat6-patch-cables1.aspx.
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