ANSI/TIA-568
EIA agreed to develop a set of standards, and formed the TR-42 committee,[4] with nine subcommittees to perform the work.
The demands placed upon commercial wiring systems increased dramatically over this period due to the adoption of personal computers and data communication networks and advances in those technologies.
The main standard, ANSI/TIA-568.0-D defines general requirements, while ANSI/TIA-568-C.2 focuses on components of balanced twisted-pair cable systems.
[6] The intent of these standards is to provide recommended practices for the design and installation of cabling systems that will support a wide variety of existing and future services.
Developers hope the standards will provide a lifespan for commercial cabling systems in excess of ten years.
Thus, the standardization process can reasonably be said to have provided at least a nine-year lifespan for premises cabling, and arguably a longer one.
The standard defines categories of shielded and unshielded twisted pair cable systems, with different levels of performance in signal bandwidth, insertion loss, and cross-talk.
Generally increasing category numbers correspond with a cable system suitable for higher rates of data transmission.
Category 3 cable was suitable for telephone circuits and data rates up to 16 million bits per second.
Backbone cabling is also used to interconnect entrance facilities (such as telco demarcation points) to the main cross-connect.
At the work area, equipment is connected by patch cords to horizontal cabling terminated at jack points.
Perhaps the most comprehensively known and most discussed feature of ANSI/TIA-568 is the definition of the pin-to-pair assignments, or pinout, between the pins in a connector (a plug or a socket) and the wires in a cable.
The termination jack is often wired according to the RJ-48X specification, providing a transmit-to-receive loopback when the plug is withdrawn.
This means either the lines don’t connect at all or likely unacceptable levels of hum, crosstalk, and noise.
The TIA-568 terminations diverge from this concept by placing a pair on pins 1 and 2 and one on 7 and 8 because, on the eight-position connector, the original arrangement of conductors would separate the outer pairs substantially, impairing balanced line performance too much to meet the electrical requirements of high-speed LAN protocols.
