As the number of LAN installations grew, additional standards were needed to address compatibility and performance between suppliers of different equipment. The existing standards were not adequate, making installation and maintenance of multiple and incompatible wiring systems difficult for installers and engineers. These serious limitations regarding system operation, adaptability and maintenance brought about a need for common cabling system requirements. International Business Machines (IBM) technical interface specification GA27-3773-1 (standard spec) was the first hierarchy of data communication cabling. This pioneered the EIA/TIA-568A standard for category cabling as we know it today.
EIA/TIA-568A & 570 Wiring - Star Wiring Topology
EIA/TIA standards are designed with flexibility in mind. Their “generic” quality not only supports future equipment and service changes, but also allows successful use of multiple vendor equipment. “Topology” refers to the architecture, of the way the network is designed. EIA/TIA-568A and 570 wiring systems are based on a “star” topology. A star topology is a system in which all workstations or devices are connected to a central location. A star topology may also support several different variations of direct connections such as ring, bus, loop, etc.
Simple Star Topology
Simple Ring Topology
Simple Bus Toplogy
Some applications require “baluns” to convert coax applications (unbalanced) to UTP applications (balanced).
The category rating system was developed by TIA as a response to the industry’s request for higher data rate specifications on applications over unshielded (UTP) and shielded (STP) twisted pair. This rating system has been integrated into the body of the EIA/TIA-568A standard document. The category rating system only applies to 100 ohm UTP and STP wiring systems. EIA/TIA-568A also allows 150 ohm STP (also called type 1) and 62.5/125 um multi-mode optical fiber.
4 pair 100 ohm UTP Category 3 cabling is the recommended minimum requirement for residential and light commercial installations. This standard provides excellent flexibility. Category 2 and 4 cables have been replaced in the mind of the industry by Category 3 and 5 cables respectively. Pair counts have also been consolidated with 4 pair for “desktop” and 25 pair for “backbone” cabling leading the way.
Commercial Building Telecommunication Standard