In the mid-1980s, consumers, contractors, vendors, and manufacturers became concerned about the lack of specifications relating to telecommunications cabling. Before then, all communications cabling was proprietary and often suited only to a single-purpose use. The Computer Communications Industry Association (CCIA) asked the EIA to develop a specification that would encourage structured, standardized cabling.
Under the guidance of the TIA TR-41 committee and associated subcommittees, the TIA and EIA in 1991 published the first version of the Commercial Building Telecommunications Cabling Standard, better known as ANSI/TIA/EIA-568 or sometimes simply as TIA/EIA-568.
Sometimes you will see the Commercial Building Telecommunications Cabling Standard referred to as ANSI/TIA/EIA-568 and sometimes just as TIA/EIA-568 and now just TIA-568. You will also sometimes see the EIA and TIA transposed. The original name of the specification was ANSI/EIA/TIA-568-1991.
Over a period of several years, the EIA released a number of Telecommunications Systems Bulletins (TSBs) covering specifications for higher grades of cabling (TSB-36), connecting hardware (TSB-40), patch cables (TSB-40A), testing requirements for modular jacks (TSB-40A), and additional specifications for shielded twisted-pair cabling (TSB-53). The contents of these TSBs, along with other improvements, were used to revise ANSI/TIA/EIA-568; this revision was released in 1995 and was called ANSI/TIA/EIA-568-A.
Progress marched on, and communications technologies advanced faster than the entire specification could be revised, balloted, and published as a standard. But it is relatively easy to create ad hoc addendums to a standard as the need arises. Consequently, five official additions to the ANSI/TIA/EIA-568-A base standard were written after its publication in 1995:
ANSI/TIA/EIA-568-A-1, the Propagation Delay and Delay Skew Specifications for 100-Ohm Four-Pair Cable Approved in August and published in September 1997, this addendum was created to include additional requirements with those in the base standard in support of high-performance networking, such as 100Base-T (100Mbps Ethernet).ANSI/TIA/EIA-568-A-2, Corrections and Addition to ANSI/TIA/EIA-568-A Approved in July and published in August 1998, this document contains corrections to the base document.ANSI/TIA/EIA-568-A-3, Addendum 3 to ANSI/TIA/EIA-568-A Approved and published in December 1998, the third addendum defines bundled, hybrid, and composite cables and clarifies their requirements.ANSI/TIA/EIA-568-A-4, Production Modular Cord NEXT Loss Test Method for Unshielded Twisted-Pair Cabling Approved in November and published in December 1999, this addendum provides a nondestructive methodology for NEXT loss testing of modular-plug (patch) cords.ANSI/TIA/EIA-568-A-5, Transmission Performance Specifications for Four-Pair 100-Ohm Category 5e Cabling Approved in January and published in February 2000, the latest addendum specifies additional performance requirements for the cabling (not just the cable) for Enhanced Category 5 installations. Additional requirements include minimum-return-loss, propagation-delay, delay-skew, NEXT, PSNEXT, FEXT, ELFEXT, and PSELFEXT parameters. Also included are laboratory measurement methods, component and field-test methods, and computation algorithms over the specified frequency range. In ANSI/TIA/EIA-568-A-5, performance requirements for Category 5e cabling do not exceed 100MHz, even though some testing is done beyond this frequency limit.
The ANSI/TIA/EIA-568-B revision was published in 2001 and incorporates all five of the addendums to the 568-A version. Among other changes, Category 4 and Category 5 cable are no longer recognized. In fact, Category 4 ceased to exist altogether, and Category 5 requirements were moved to a "for reference only" appendix. Category 5e and Category 6 replace Categories 4 and 5 as recognized categories of cable. The standard is currently being published in ANSI/TIA-568-C revision in 2009. This standard now includes a Category 6A cabling for 10Gbps applications.
This chapter describes both the ANSI/TIA-568-C and ISO/IEC 11801 Ed. 2 cabling standards. You may wonder which standard you should follow. Though these two standards are quite similar (ISO/IEC 11801 was based on ANSI/TIA/EIA-568), the ISO/IEC 11801 standard was developed with cable commonly used in Europe and consequently contains some references more specific to European applications. Also, some terminology in the two documents is different and some of the internal channel requirements for CAT-6A are different.
If you are designing a cabling system to be used in the United States or Canada, you should follow the ANSI/TIA-568-C standard. You should know, however, that the ISO is taking the lead (with assistance from TIA, EIA, CSA, and others) in developing new international cabling specifications, so maybe in the future you will see only a single standard implemented worldwide that will be a combination of both specifications. Also, note that whereas 568-C contains both components, permanent link and channel specifications, 11801 contains only permanent link and channel requirements. The component requirements are contained in separate documents that are referenced in 11801.