All cabling standards and draft standards, ISO/IEC 11801, EIA/TIA 568 and EN 50173, use classification systems for specifying the transmission path. One speaks of link classes for end-to-end connections. ISO/IEC 11801 recognizes the classes "A", "B", "C" and "D" for TP cables. In addition, the DIN draft 44312-5 for the link classes "E" and "F" was adopted in ISO/IEC 11801, as were the link classes "EA","FA" and "G", which were added later.
A link class specifies the transmission behavior for the complete transmission path up to the telecommunications connection box.
The link specifications include all transmission media, connector elements, patch panels and the junction box. The workstation cabling is deliberately left out of the specification because some telecommunications end devices are supplied directly with the connecting cable, but there is also the possibility of uncontrolled replacement of connecting cables, which would affect the specifications.
Link classes for applications up to 10 Gigabit EthernetClass A: Applications with low data rates and frequencies up to 100 kHz. This class is suitable for X.21/V.11, basicISDN, for example.
Class B: Voice applications with frequencies up to 1 MHz, e.g. for basic and primary multiplex connection of ISDN.
Class C: Voice and data transmission with frequencies up to 16 MHz. This class can be used for 10Base-T, for Token Ring 4/16 Mbit/s or PBX technology. Link classes "A", "B" and "C" are no longer considered in the newer standards.
Class D: Voice and data transmission with frequencies up to 100 MHz. Used in Fast Ethernet, TPDDI.
Class E: Voice and data transmission and multimedia with frequencies up to 250 MHz, including ATM 155 and 1000Base-T. Class E allows the use of high-quality overall shielded S/UTP cables or preferably four-pair S/STP cables. With regard to the connection technology, improved RJ45 plugs and sockets are used.
Class EA: The link class "EA" has a transmission bandwidth of 500 MHz and is suitable for high-speed networks. This link class is used in 10GBase-T, among others.
Classes F and FA: Voice, data transmission and multimedia applications with frequencies up to 600 MHz and 1,000 MHz respectively. These link classes, specified according to E-DIN 44312-5, are suitable for use with ATM 155/622, Gigabit Ethernet and 10GBase-T of 10 Gigabit Ethernet.Class FA: This link class is specified for frequencies up to 1 GHz. It requires data cables and data connectors of category 7A. Class FA cabling is characterized by significantly improved parameters compared to class "F". For example, the attenuation-to-crosstalk ratio (ACR) at 500 MHz is 28.3 dB better than that of the F class. Likewise, the values for external crosstalk (AXT) and powersum NEXT (PSNEXT) are significantly higher.
Class G is specified for frequencies up to 1 GHz. It is used in 10GBase-T, 40GBase-T and 100GBase-T.
The definitions, the designations and the scope of the link classes are different in the American EIA/TIA standard 568 compared to the international standard ISO/IEC 11801and the German standard DIN 50173.