Category 6 (CAT6) Cabling
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 500MHz 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.
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 so long as 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 make them too thick to attach to 8P8C connectors without a special modular piece; they are technically not standard compliant.
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, and this does not matter 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, Cat-6 crossover cables are rare. Crossover cables are needed only between 10/100 Mb/s hosts or switches where neither end supports Auto-MDIX, and then Cat-5 is sufficient for this purpose.
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 Cross-talk (AXT) as compared to Cat6 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.
TIA comp. Cat. 6A ≠ ISO/IEC Cat. 6 A comp.[clarification needed]
The maximum allowed length of a Cat-6 cable is 100 meters (330 ft) when used for 10/100/1000baseT. 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 meters of patch cabling will reduce the permissible length of horizontal cable.
When used for 10GbaseT, Cat-6 cable’s maximum length is 55 meters (180 ft) in a favorable alien crosstalk environment, but only 37 meters (120 ft) in a hostile alien crosstalk environment such as when many cables are bundled together. 10GbaseT runs of up to 100 meters (330 ft) are permissible using Cat-6a.
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.
Shielded Category 6a cable must have the foil grounded at one end to achieve specified alien crosstalk performance. 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.
Low End Cable Problem
The Communications Cable and Connectivity Association, Inc.(CCCA) cautioned that many offshore-manufactured communications cable products could present significant fire risk. In response to concerns from the industry, the CCCA commissioned an independent laboratory to analyze whether nine randomly selected offshore samples of these products met U.S. minimum requirements for performance and safety. Test results showed that none of the samples fully met all of the minimum requirements and eight of the nine samples failed to meet the National Fire Protection Association (NFPA) minimum code requirements for low flame spread and/or smoke safety requirements for installation in commercial buildings, schools and multi-tenant residences. Many of the samples failed the flame spread and smoke tests catastrophically. Because of the seriousness of these safety concerns, the CCCA plans to work in cooperation with the major leading independent telecommunications industry testing agencies to establish a new product certification program. Although details of the proposed program have not yet been established, a key component will be independent laboratory testing of structured cabling products that have been procured from point–of-sale locations..
Manufacture of Solid Core Cable
Copper Rod Breakdown The first step in low voltage cable production is copper rod breakdown. Copper is sent to the factory in 5,000 lb coils. These copper coils are continuously drawn through diamond dies that drastically reduce the diameter of the copper to 10 or 12 gauge. Lubrication is used during this process to reduce the amount of friction and heat on the copper cable. Once completed, the copper is stacked in vertical coils, called Stem Packs. These stem packs are then transferred to another drawing operation that further reduces the gauge of the copper. During this stage, the copper is also charged with an electrical current. This anneals the copper, which is a softening process. Once annealed and cooled off, the copper runs through a laser measurement system, to verify it is within manufacturing specifications.
Copper Insulation Process The copper insulation process is continually monitored and controlled up to +/- .0001″. Once the copper is insulated, it runs through a water cooling trough, allowing the wire jacket to properly harden.
Copper Twisting Twisting helps reduce crosstalk between the individual pairs of wire. Some Cat6 premise cables include a center spline, or wire separator, to further reduce crosstalk and increase performance. Copper twisting is accomplished by running each individual wire through multiple faceplates. This helps control pair position. Once twisted, we have what’s called a Cable Unit.
Jacketing The cable unit then goes through the jacketing process. This step varies, depending on the type of cable being manufactured. OSP cable typically uses a black polyethylene or UV rated Polyvinyl chloride (PVC). For Cat3, Cat5e and Cat6 Premise cable, varying grades of PVC are used, depending on flame safety rating requirements. This steps starts off with molten plastic being extruded at high pressure and formed around the moving cable core. Shielding, ripcords, armoring and water blocking compound may also be applied at this step. Cables that require dual shielding or double armor will need to repeat this process. Once completed, the cable passed through a long cooling bath, then through a laser micrometer to verify the final diameter.
Printing Printing is done just before the cable is put in its final packaging. For OSP cable, a hot foil printing process is used, that leaves an indented print in the cable jacket. For Premise cable, a high speed ink jet printer is used. Some cable manufacturers print footage marking from 1000–0 ft, making it very easy to determine how much cable is left in the box, or for measuring out cable runs. Other manufacturers use a six digit footage mark, making the process a little harder.
Coiling The completed cable is then wound onto a reel or coil. the coiling process requires very precise tension controls to ensure the cable won’t tangle when being pulled out of the box.
Final Testing Once the cable is printed and coiled, it goes through one last set of tests. The manufacturer will test it against a large set of mechanical and electrical performance specifications. Once tested, the cable is ready for shipment.