10gbase-t and class six cabling standards

2004, the Working Group 802.3an was formally established, the draft 10GBASE-T the same year in June with a first draft, the official version is expected to be announced in 2006. At the June 2004 meeting, the Working Group revised the PHY encoding from PAM5 to PAM8, and the bandwidth requirements for Class E-level cabling systems were modified to 500MHz accordingly.
　　
By contrast, TIA TR-42 is developing TSB-155 and 568-B.2-10, the former for the existing installed six-class cabling system, which is the newly revised extended six-class standard. These two standards are similar to those promulgated in 1999 by TSB-95 and 568-a-5, the difference being one of the 10G-oriented six classes, and one for the five types of gigabit.
　　
TSB-155 's goal is to verify that the existing six-class cabling system can support 10GBASE-T applications at a distance of 55 meters. According to the latest requirements of ieee802.3an, the test specification of each channel and link parameter is extended to 500MHz, but the index value within 250MHZ is consistent with the original six categories. In addition, the external crosstalk parameter Anext and PS Anext are added, and other parameters such as Afext and Psafext are not referenced at present.
　　
The goal of 568-B.2-10 is to define a new "extended six" standard that includes wiring components and system specifications and test procedures to support 10gbase-t balanced twisted pair transmission at 100.4-meter connection points. This standard also defines the bandwidth in 500MHz, but compared with TSB-155, it puts forward higher performance requirements, such as external crosstalk and insertion loss allowance. This standard is expected to be published prior to the IEEE 802.3an 10GBASE-T standard.
　　
ISO/IEC JTC 1/SC 25 Standards Committee is also revising the existing standards, in the latest document N981, in the update of the documentation from the IEEE 10GBASE-T workgroup request, in the original iso11801:2002 ED2 based on the expansion of Class F/E bandwidth performance, From the angle of shielding external crosstalk, the indexes of unbalance attenuation (non-equilibrium attenuation), coupling attenuation (coupling attenuation) and PS Anext are increased.
　　
In the development of six-class cabling standards for 10G applications, the following issues are of concern to users: Can the five types of enhancements support 10GBASE-T?
　　
Ieee802.3an Working Group after study that: five types of cable after all, there is a need for electronic equipment tolerance or compensation defects, including next, Fext, but also to consider external crosstalk interference. On the physical layer of the network device, the number of transistors used to overcome the limitations of the five-class cable performance exceeds 50% of the total. In addition, the physical layer of high integration, technical complexity, compared with the enhanced five classes, six systems have better anti-noise performance, can provide a more transparent, more versatile transmission channel, especially in high frequencies.
　　
Tests show that 10G Ethernet requires at least 500MHz (initially 625MHz) linear transmission performance. Most enhancements to the five-class cable are only 150MHz or 250MHz, and the standard only requires 150MHz. The six class is not forced to achieve 500MHz performance, but for high bandwidth transmission, it is a better medium; many manufacturers provide cable nominal 600MHz, it is expected to some applications require higher performance;
　　
Network chips and device manufacturers need a certain level of performance to enable them to produce products that deliver 10G on copper cables. The average noise resistance of class six systems on 500MHz is higher than that of five classes. The larger the capacity of the cabling system, the more the network device manufacturer can make less compensation for its products. The result is a cheaper solution, and people no longer rely on electronic components to compensate for lower-level wiring techniques. Based on the above considerations, the Ieee802.3an team has now abandoned its support for enhanced five-class cabling systems.