10GBASE-T and Structured Cabling

Until recently, Gigabit Ethernet was considered to be the limit that would be very difficult to overcome on metallic structured cabling. Now it is obvious that 1 Gbps is not the maximum transmission rate that can be achieved on copper twisted pair cables. The new 10GBASE-T Ethernet standard that was published in June 2006 by the IEEE 802.3an group proves this. In the first stage, this new protocol with transmission speeds of up to 10 Gbps was primarily employed in backbone distribution systems, SAN's (Storage Area Networks), and data centers. But now, it is quite common to use the 10GBASE-T protocol also on horizontal cabling in various network environments (e.g. commercial and governmental offices, universities, industry premises etc).

1. Running 10GBASE-T on Currently Existing Cabling
The documents TIA TSB 155 and ISO/IEC 24750 deal with operating the 10GBASE-T protocol over currently existing Category 5E and Category 6 cabling systems. The test results performed in connection with these bulletins showed that it is not possible to run 10 Gbps data transfers on Category 5E networks and that on current unshielded Category 6 cabling the 10GBASE-T protocol can operate only for a distance of up to 55 m. This length limitation should be improved on shielded Category 6 systems but it is highly recommended to use Category 6A components for all new 10G installations. It is the new Category 6A that was primarily designed to provide full compatibility with no length limitations for 10GBASE-T. The factor that plays an important role in the above mentioned length restriction is the so-called Alien Crosstalk. It is influenced by the amount of cross-talk signal from external sources, such as other cables in a cable bundle, electronic devices operated nearby, telephones, etc.

2. New Requirements for Future Cabling Systems for 10GBASE-T
As it was already mentioned, a new category with the bandwidth of up to 500 MHz (i.e. double of what is available for the current Category 6) was defined to ensure full compatibility of cabling systems with the 10GBASE-T protocol. This new category is referred to as “Augmented Category 6” or “Category 6A” and was published in TIA 568B.2-10 in April 2008 and recently revised in TIA 568C.2. The Category 6A specifies both permanent link and channel systems as well as individual component requirements.

In terms of classes for the 10GBASE-T protocol, the Class E_A is also defined in ISO/IEC 11801 Amendment 2 for both permanent link and channel topologies. However, unlike in the TIA specification, the Class E_A in the ISO/IEC standards is defined for both screened and unscreened cabling systems.