History of Structured Cabling

Until the beginning of 1980’s, the majority of computer networks worked in a host/terminal mode. Applications as well as data were stored centrally on a host computer and user stations called terminals handled them in this centralized way. Considering the text character of this type of communication, it was not necessary to build special high capacity transmission paths for terminal networks. However, their prevalence ended in 1981 when IBM launched their first personal computer onto the market. This new type of workstation was equipped with a local memory and outputs for connecting various peripherals. This resulted in a different—decentralized—mode of operation. This greater independence brought two important issues:(1.) difficult administration and (2.) mutual user co-operation.

Therefore, it was necessary to find a way that would enable to connect new PCs' into a computer network through which it would be possible to share files, applications, and costly peripherals in the same manner as in terminal networks.In the beginning, several solutions arose from different producers. However, differences in technologies and diversity in components of these new systems led to their mutual incompatibility. A solution to this situation was to design a universal system that would set recommended standards determining electrical and physical characteristics of cables as well as connecting hardware. At the beginning of 1990’s, the American National Standards Institute (ANSI) asked Telecommunications Industry Association (TIA) and Electronic Industries Alliance (EIA) to propose a universal standard for metallic cabling systems. One of the most suitable ways for the new cabling system design was to use the already existing solution introduced by AT&T. These networks used telephone distribution systems that were installed in most office buildings at that time. They had a star topology and used a twisted pair cable as the main transmission medium. The outcome of the commission work was the first specification for structured cabling published in July 1991. It was referred to as ANSI/TIA/EIA 568. Together with the technical bulletins TSB-36 and TSB-40 issued a little later, the new documents defined basic transmission requirements for Category 3, 4, and 5. In 1995, the first update of the above mentioned standard and also the first version of the international ISO/IEC 11801 standard were issued. In 1996, CENELEC published the first European specification for structured cabling cables and components named EN 50173. As the result of a new high-speed protocol development (i.e. Gigabit Ethernet), all these standards were updated in 2000 and 2002. The updates defined new parameters that must be met by structured cabling components in order to comply with the new protocol requirements. The documents were supplemented with further measured or numerated parameters, such as PSNEXT, PSACR, PSELFEXT, Delay Skew etc. In these specification updates, the new Category 5 (today known as Category 5E), Category 6, and Category 7 were introduced.