FOA Guide

Changes In TIA-568 Standard For Premises Cabling Systems

In  2011 TIA changed the nomenclature of structured cabling systems. Many years later, the earlier terms which came from a century of use in the telephone system are still preferred by many in the industry.

The terminology in TIA-568-C.0, Generic Telecommunications Cabling For Customer Premises, has changed to a more generic (i.e. not traditional telecom) nomenclature. Current plans are to revise the other T568/T569/T570 documents to this nomenclature in the future.

Unfortunately, all this can be confusing, so we'll present the TIA wording and explain our interpretation in CAPS and give you a diagram of our explanation.

The traditional terms for the location of the ends of the cabling or interconnections have been changed to "connection points."

Distributor C: Initial or central connection point in a hierarchical star topology. EQUIPMENT ROOM OR MAIN CROSS CONNECT

Distributor B: Intermediate connection point between Distributor A and Distributor C in a hierarchical star topology.  AN OPTIONAL SECOND PATCH IN EQUIPMENT OR TELECOM ROOM OR MEDIA CONVERTER AND/OR REPEATER

Distributor A: Intermediate connection point between Distributor C and Equipment Outlet in a hierarchical star topology. HORIZONTAL CROSS CONNECT, e.g. TELECOM ROOM or ZONE MUTOA 

Equipment Outlet: Final connection point in a hierarchical star topology. WORK AREA OUTLET

In a typical commercial building, Distributor C  would be the main cross-connect, Distributor A would be the horizontal cross-connect, and Equipment Outlet would be the telecommunications outlet (TO. ) Distributor B is optional and not often used.

Connecting these points are "cabling subsystems" defined as:

Cabling Subsystem 2 or 3: Cabling between either Distributor A and Distributor C or Distributor B and Distributor C. BACKBONE

Cabling Subsystem 2: Cabling between Distributor A and Distributor B. CROSS CONNECT

Cabling Subsystem 1: Cabling between  Distributor A and Equipment Outlet. HORIZONTAL

In addition, some of the definintions have changed:

Centralized cabling, Fiber optics with a direct connection from the equipment to user is defined as: A cabling configuration from Distributor C to a centralized cross-connect using pull through cables, an interconnect, or splice at Distributor A.

Consolidation point: A connection facility within Cabling Subsystem 1 for interconnection of cables extending from building pathways to the equipment outlet.

These drawings illustrate some of the options within the standard architecture.

Below is the "traditional" view of TIA-568 architecture:

TIA 568 C Architecture

Distributor B is optional and can be used for a connection, e.g. fiber splices, or media converters:

TIA 568 C Architecture

In fact, no intermediate connections are required, e.g. centralized fiber:

TIA 568 C Architecture

Within Connection Point C, there are two methods of connection from active equipment to Cabling Subsystem 3, the interconnect and cross-connect configurations:

TIA-568 CP-C

Here is a diagram of old and new nomenclature in a typical structured cabling system using the illustration we have used previously:

TIA-568-C Nomenclature

Premises Cabling Website Contents

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Overview of Premises Cabling and Standards  
UTP CablesPower Over Ethernet.
UTP Terminations, (Tutorial) UTP Termination
UTP Installation VHO  66 Block, 110 Block, Jacks, Plugs  
UTP Testing,  UTP Wiremapping  
Coax Cable  VHO Coax Termination  
Fiber Optics in Premises Cabling
Design, New T-568-C Nomenclature
Premises Cabling Installation
See the "Fiber Optic Technology and Standards" Section below for information on networks, etc.
FOA Lectures on Premises Cabling and videos about cable preparation, termination, splicing and testing on FOA videos


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