Overview #Before we get started with actually building our cables, let's take a few minutes to explore the two different wiring standards for network cabling.
As you may know, every company that develops a product for the computer industry tries to establish its product as the standard all others should follow. However, that doesn't always work out in the best interest of the consumer. In many cases, an independent organization must step in and guide the industry to a standard.
In the case of the wiring standard, the Electronic Industries Alliance (EIA)|http://www.eia.org/] and the Telecommunications Industry Association (TIA)|http://www.tiaonline.org/] got together in 1991 and set a standard for network cable wiring called the EIA/TIA-568 Standard for Commercial Building Telecommunications Wiring. The EIA/TIA-568 standard describes the performance and installation specifications for network cabling, covering both the cable itself and how it’s connected to modular plugs and jacks.
As you may have guessed, the EIA/TIA-568 standard's cable performance specifications for each of the Category 1,2,3,4,5,6 etc. cabling. Category 5 is the lowest we would now recommended for use on any current network wiring plans (The EIA/TIA-568 standard also covers Categories 1 through 4 cabling). Of course, the main objective of the EIA/TIA-568 standard is to give all manufacturers the ability to build equipment and components that will interoperate in a standardized cabling environment.
The EIA/TIA-568 standard has two schemes for how the wire is connected to modular plugs and jacks, the T568A and T568B. These standards are essentially the color code patterns that you use for connecting the colored wires in the cable with the connectors in the RJ-45 modular plugs and jacks.
The US Government uses the T568A wiring standard for all network wiring done under United States federal government contracts. In addition because it provides backward compatibility for both one pair and two pair Universal Service Order codes (AT&T) USOC wiring schemes, the T568A wiring pattern is recognized as the preferred wiring pattern for this standard.
Most other network configurations use the T568B wiring standard. This standard is identical to the AT&T 258A, which was the preferred and most widely used wiring scheme before the adoption of the EIA/TIA standards. However, this wiring standard only provides backward compatibility with one-pair USOC wiring schemes.