According to TIA/EIA 568 documents, the wiring standard is designed to provide the following features and functions: • A generic telecommunication wiring system for commercial buildings
Trang 1TI A/ EI A St r u ct u r e d Ca blin g St a n da r ds
In the mid-1980s, the TIA (Telecommunications Industry Association) and the EIA (Electronic Industries Association) began developing methods for cabling buildings, with the intent of developing a uniform wiring system that would support multivendor products and environments In 1991, the TIA/EIA released the TIA/EIA 568
Commercial Building Telecommunication Cabling standard Note that the
ISO/IEC-11801 Generic Customer Premises Cabling standard is an international cabling
standard that is based on the ANSI/TIA/EIA-568 cabling standard
The TIA/EIA structured cabling standards define how to design, build, and manage a cabling system that is structured, meaning that the system is designed in blocks that have very specific performance characteristics The blocks are integrated in a
hierarchical manner to create a unified communication system For example,
workgroup LANs represent a block with lower-performance requirements than the backbone network block, which requires high-performance fiber-optic cable in most cases The standard defines the use of fiber-optic cable (single and multimode), STP (shielded twisted pair) cable, and UTP (unshielded twisted pair) cable
The initial TIA/EIA 568 document was followed by several updates and addendums as outlined below A major standard update was released in 2000 that incorporates previous changes
• TI A/ EI A- 5 6 8 - A- 1 9 9 5 ( Com m e r cia l Bu ildin g Te le com m u n ica t ion s
W ir in g St a n da r ds) Defines a standard for building cable system for
commercial buildings that support data networks, voice, and video It also defines the technical and performance criteria for cabling
• TI A/ EI A- 5 6 8 - A u pda t e s ( 1 9 9 8 - 1 9 9 9 ) The TIA/EIA-568 was updated several times through this time period Update A1 outlined propagation delay and delay skew parameters Update A2 specified miscellaneous changes Update A3 specified requirements for bundled and hybrid cables Update A4 defined NEXT and return loss requirements for patch cables Finally, update A5 defined performance requirements for Enhanced Category 5 (Category 5E)
• TI A 5 6 8 - B.1 - 2 0 0 0 ( Com m e r cia l Bu ildin g Te le com m u n ica t ion s W ir in g
St a n da r d) The year 2000 update packages all the previous addendums and service updates into a new release and, most important, specifies that
Category 5E cable is the preferred cable type that can provide minimum
acceptable performance levels Several addendums were also released that specify technical information for 100-ohm pair cable, shielded twisted-pair cable, and optical fiber cable
• TI A/ EI A- 5 6 9 - A- 1 9 9 5 ( Com m e r cia l Bu ildin g St a n da r d for
Te le com m u n ica t ion s Pa t h w a y s a n d Spa ce s) This standard defines how
to build the pathways and spaces for telecommunication media
• TI A 5 7 0 - A- 1 9 9 8 ( Re side n t ia l a n d Ligh t Com m e r cia l
Te le com m u n ica t ion s W ir in g St a n da r d) This standard specifies residential cabling
• TI A/ EI A- 6 0 6 - 1 9 9 4 ( Bu ildin g I n fr a st r u ct u r e Adm in ist r a t ion
St a n da r d) This standard defines the design guidelines for managing a telecommunications infrastructure
• TI A/ EI A- 6 0 7 - 1 9 9 5 ( Gr ou n din g a n d Bon din g Re qu ir e m e n t s) This standard defines grounding and bonding requirements for telecommunications cabling and equipment
The current trend is to evolve the standards to support high-speed networking such
as Gigabit Ethernet and define advanced cable types and connectors such as four-pair
Trang 2Category 6 and Category 7 cable Category 6 is rated for channel performance up to
200 MHz, while Category 7 is rated up to 600 MHz See "Cable and Wiring" for more information about cable types
The remainder of this section discusses the TIA/EIA-568 standard in general, rather than any specific release According to TIA/EIA 568 documents, the wiring standard is designed to provide the following features and functions:
• A generic telecommunication wiring system for commercial buildings
• Defined media, topology, termination and connection points, and
administration
• Support for multiproduct, multivendor environments
• Direction for future design of telecommunication products for commercial enterprises
• The ability to plan and install the telecommunication wiring for a commercial building without any prior knowledge of the products that will use the wiring
The layout of a TIA/EIA 568-A structured cable system is illustrated in Figure T-8 The hierarchical structure is apparent in the multifloor office building A vertical backbone cable runs from the central hub/switch in the main equipment room to a hub/switch in the telecommunication closet on each floor Work areas are then individually cabled to the equipment in the telecommunication closet The logical hierarchy is illustrated in Figure T-9
Figure T-8 (see book, page 1248)
Figure T-9 (see book, page 1249)
The TIA standard defines the parameters for each part of the cabling system, which includes work area wiring, horizontal wiring, telecommunication closets, equipment rooms and cross- connects, backbone (vertical) wiring, and entrance facilities Each of these is described next Additional details, specifications, and illustrations are
available at the Siemon's Web site listed on the related entries page
Work Area
The work area wiring subsystem consists of the communication outlets (wallboxes and faceplates), wiring, and connectors needed to connect the work area equipment (computers, printers, and so on) via the horizontal wiring subsystem to the
telecommunication closet The standard requires that two outlets be provided at each wall plate-one for voice and one for data
Horizontal Wiring
The horizontal wiring system runs from each workstation outlet to the
telecommunication closet The maximum horizontal distance from the
telecommunication closet to the communication outlets is 90 meters (295 feet)
independent of media type An additional 6 meters (20 feet) is allowed for patch cables at the telecommunication closet and at the workstation, but the combined length cannot exceed 10 meters (33 feet) As mentioned earlier, the work area must provide two outlets The horizontal cable should be four-pair 100-ohm UTP cable (the latest standards specify Category 5E), two-fiber 62.5/125-mm fiber-optic cable, or
Trang 3multimode 50/125-mm multimode fiber-optic cable Coaxial cable is no longer
recommended
Telecommunication Closet
The telecommunication closet contains the connection equipment for workstations in the immediate area and a cross-connection to an equipment room The
telecommunication closet is a general facility that can provide horizontal wiring
connections, as well as entrance facility connections There is no limit on the number
of telecommunication closets allowed Some floors in multistory office buildings may have multiple telecommunication closets, depending on the floor plan These may be connected to an equipment room on the same floor
Equiptment Rooms and Main Cross-Connects
An equipment room provides a termination point for backbone cabling that is
connected to one or more telecommunication closets It may also be the main cross-connection point for the entire facility In a campus environment, each building may have its own equipment room, to which telecommunication closet equipment is
connected, and the equipment in this room may then be connected to a central
campus facility that provides the main cross-connect for the entire campus
Backbone Wiring
The backbone wiring runs up through the floors of the building (risers) or across a campus and provides the interconnection for equipment rooms and
telecommunication closets The distance limitations of this cabling depend on the type
of cable and facilities it connects Refer to Figure T-11 and the following table Note that UTP is limited to 90 meters
Entrance Facilities
The entrance facility contains the telecommunication service entrance to the building This facility may also contain campus-wide backbone connections It also contains the
network demarcation point, which is the interconnection to the local exchange
carrier's telecommunication facilities The demarcation point is typically 12 inches from where the carrier's facilities enter the building, but the carrier may designate otherwise
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