Category 6 cable, commonly referred to as Cat 6, is a standardized twisted pair cable for Ethernet and other network physical layers that is 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 specifies performance of up to 250 MHz.
Whereas 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 100 meter distance as previous Ethernet variants
Category 6 cable can be identified by the printing on the side of the cable sheath.
Cat 6 patch cables are normally terminated in 8P8C modular connectors. If Cat 6 rated patch cables, jacks and connectors are not used with Cat 6 wiring, overall performance is degraded and may not meet Cat 6 performance specifications.
Connectors use either T568A or T568B pin assignments; performance is comparable provided both ends of a cable are terminated identically.
When used for 10/100/1000BASE-T, the maximum allowed length of a Cat 6 cable is up to 100 meters (328 ft). This consists of 90 meters (295 ft) of solid "horizontal" cabling between the patch panel and the wall jack, plus 5 meters (16 ft) of stranded patch cable between each jack and the attached device. For 10GBASE-T, an unshielded Cat 6 cable should not exceed 55 metres.
Category 6 and 6A cable must be properly installed and terminated to meet specifications. The cable must not be kinked or bent too tightly (the bend radius should be at least four times the outer diameter of the cable). The wire pairs must not be untwisted and the outer jacket must not be stripped back more than 0.5 in (12.7 mm).
Cable shielding may be required in order to improve a Cat 6 cable's performance in high electromagnetic interference (EMI) environments. This shielding reduces the corrupting effect of EMI on the cable's data. Shielding is typically maintained from one cable end to the other using a drain wire that runs through the cable alongside the twisted pairs. The shield's electrical connection to the chassis on each end is made through the jacks. The requirement for ground connections at both cable ends creates the possibility that a ground loop may result if one of the networked chassis is at different instantaneous electrical potential with respect to its mate. This undesirable situation may compel currents to flow between chassis through the network cable shield, and these currents may in turn induce detrimental noise in the signal being carried by the cable.