Transition Networks M/GE-ISW-SFP-01-PD User Manual page 10

Transition Networks M/GE-ISW-SFP-01-PD User Guide
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.
Like most of the earlier twisted-pair cables, Category 6 cable contains four twisted wire pairs. Attenuation,
Near End crosstalk (NEXT), and PSNEXT (Power Sum NEXT) in Cat 6 cable and connectors are all
much lower than Cat 5 or Cat 5e, which uses 24 AWG wire. The increase in performance with Cat 6
comes mainly from increased (22 AWG) wire size. Because the conductor sizes are generally the same,
Cat 6 jacks may also be used with Cat 5e cable.
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 to that of the cable or connector.
Connectors use either T568A or T568B pin assignments; although performance is comparable provided
both ends of a cable are the same, T568B is a deprecated standard in the US and no longer supported by
TIA.
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.
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 is defined at frequencies up to 500
MHz - twice that of Cat. 6. Category 6a performs at improved specifications, in particular in the area of
alien crosstalk, as compared to Cat 6 UTP (unshielded twisted pair), which exhibited high alien noise in
high frequencies.
The global cabling standard ISO/IEC 11801 has been extended by the addition of amendment 2, which
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, which offer superior
performance compared to existing products based on the American TIA standard.
Note the 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 to the EIA/TIA specification. The 3 dB represents a 100% increase
of near-end crosstalk noise reduction when measured in absolute magnitudes.
Maximum Length
When used for 10/100/1000BASE-T, the maximum allowed length of a Cat 6 cable is 100 meters or 328
feet. 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 10GBASE-T, Cat 6 cable's maximum length is 55 meters (180 ft) in a favorable alien
crosstalk environment, but only 37 meters (121 ft) in a hostile alien crosstalk environment, such as when
many cables are bundled together. However, because the effects of alien crosstalk environments on
cables are difficult to determine prior to installation, it is highly recommended that all Cat 6 cables being
used for 10GBASE-T are electrically tested once installed. With its improved specifications, Cat6 A does
not have this limitation and can run 10GBASE-T at 100 meters (330 ft) without electronic testing.
Installation Notes
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 1/2 inch (1.27 cm). All shielded cables must be grounded for safety and effectiveness and a
continuous shield connection maintained from end to end. Ground loops develop when there is more than
one ground connection and the difference in common mode voltage potential at these ground
connections introduces noise into the cabling. Note that 23 or 24 AWG wire is allowed if the ANSI/TIA-
568-B.2-1 performance specifications are met. The figure below shows the pins on plug face; note that
the socket is the reverse of the plug pinout shown below. For more information, see the TIA web site or
the IEEE web site.
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