International standardization activities for application-neutral cabling systems began in 1991. The first draft of the international standard ISO/ IEC 11801 was available in 1993 and published as early as 1995. The 11801 standard and the largely identical European standardEN 50173 are relevant for Germany. They define a scope for a site extent of up to 3 km and for an office area of up to 1 million square meters with 50 to 50,000 terminals. The standards support voice, data, text, image and video applications and therefore contain the specifications for configuration, implementation, performance and compliance. They also describe recommendations for the general structure of a cabling system and classify the cable types to be used as well as the end-to-end connections( link class).
Scope and topologies of the 11801 standard
An essential component of the cabling standards is a hierarchical structure with star-shaped cabling. The geographical scope is structured into primary cabling, secondary c abling and tertiary cabling. The structuring and the star-shaped structure of the cabling have several advantages: New network segments can easily be added without affecting the entire structure. If faults occur in one network segment, they remain restricted to this network segment and do not affect the functionality of other subnetworks. Redundancy links can be provided against the failure of a primary link. The failure of a backbone network does not affect the communication functions within the subnetworks. In the tertiary areas, different network topologies - star, bus, ring - can be implemented by appropriate wiring of the distributors.
Functional components of the cabling standard
The functional elements of the cabling areas include the primary cables and the site distributor(SV) in the sitecabling, the secondary cables and the building distributor(GV) in the building cabling, and the tertiary cables, the floor distributors ( EV), any cabledistributors (KV) and the telecommunications connection boxes ( TA) in the floor cabling. The cable lengths for the primary area were specified as 1,500 m, for the secondary area as 500 m, and for the tertiary area as 90 m. The definition range for the link classes ends at the telecommunications outlet; the up to 10 m long connecting cable is not taken into account, only the range from the patch panel to the crossconnect is considered in the link class.
Transmission media specified in the 11801 standard
In terms of the transmission media that can be used, the standards are limited to fiber optic cables and symmetrical TP cables. Whereby the recommendations for all cabling areas exempt both alternatives: Gradient fiber with 62.5/125 µm and UTP or STP cable. For cable specifications, the standards define three categories, 3, 4 and 5. The transmission characteristics for these cables, as well as for the connection technology, are specified in so-called link classes, which are identified with the word Class followed by a letter "A," "B," "C," "D," "E" or "F." Class "D", for example, has a transmission behavior that is given by the characteristics of the transmission components of category 5, Class "F" is based on components of category 7.
For the classification of the cables, as for the link classes, there are proposals from DIN to extend the frequency range of the cables and the transmission characteristics of the link classes. Categories 6 and 7, which were introduced into the international standard as German draft standard E DIN 44312-5, extend the frequency range from 100 MHz to 250 MHz ( Cat. 6) and 600 MHz (Cat. 7); the corresponding link classes are called Class E and F.
The network application classes E and F support ATM, Gigabit Ethernet and 10 Gigabit Ethernet. In order to achieve future security and a high level of investment protection, the draft is backward compatible with the European standard EN 50173.
Components in the workstation area
In terms of connection components, the standards for fiber optic cables provide for the SC connector and the much more compact LC connector, which is to replace the SC connector. For twisted copper cables, only the RJ45 connector is recommended in the distribution area as well as in workplace cabling. However, the RJ45 connector can only be used to a limited extent for higher bandwidths, corresponding to category 7, since it only achieves the required NEXT values when the outer pairs of connections are wired. Since this would have led to a restriction of flexibility, the GG-45 connector as well as the TERA connector were approved for cabling according to link class F. The IEC and ISO have standardized the GG-45 connector.
Further changes affect the tertiary range. This area consists of the distance from the transmission device to the crossconnect, the patch field with patch cable, the horizontal cabling (90 m) with the Tk junction box and the connecting cable to the terminal device. In the link specification of the 1st version, the distribution area and the floor cable were considered, but not the connecting cable. In the revision of the standard, the Link specification is replaced by the "Permanent Link" and the"Channel". The Permanent Link is the area between the patch panel and the telecommunications junction box, and the Channel defines the end-to-end connection in the tertiary area between the transmission device and the terminal. The channel specification therefore takes into account all components and cables of the floor cabling: The cross connect with distribution cable, the patch panel with patch cable, the floor cable, the junction box and the connecting cable. The standards specify all cable specifications such as the characteristic impedance, attenuation, near-end crosstalk (NEXT) and attenuation-to-crosstalk ratio( ACR), as well as the transmission characteristics of the connectors.
In 2018, the ISO/IEC 11801 standard was updated, expanded and restructured. According to this, there is the following structure: 11801-1: General, 11801-2: Office buildings, 11801-3: Industrial, 11801-4: Residential, 11801-5: Data centers, and 11801-6: Building automation.