5.4 Cabling Structure

5.4 Horizontal Cabling System Structure

The horizontal wiring extends from the wall outlet to the wiring closet which is also sometimes referred to as a telecommunications closet. This cabling run includes:

  • the wall outlet
  • the horizontal cable
  • the cross-connects or patch cables in the closet

Patch Panels

In an Ethernet LAN star topology, the horizontal cabling runs, which come from the work areas, usually terminate at a patch panel. A patch panel is an interconnecting device through which horizontal cabling runs can be connected to other networking devices, such as hubs and repeaters. More specifically, a patch panel is a gathering of pin locations and ports. A patch panel acts as a switchboard, where horizontal cables coming from workstations, can connect to other workstations to form a LAN. In some instances, a patch panel can also provide locations for devices to connect to a WAN, or to the Internet. This connection is described by TIA/EIA-568-A as a horizontal cross-connect (HCC).

On the front side of a patch panel there are ports. They resemble the ports on faceplates of telecommunications outlets in the work area. Like the RJ-45 ports, the ports on patch panels take the same size plugs. Patch cords that connect to these ports make possible the interconnection of computers and other network devices (eg: hubs, repeaters, and routers) that are also attached to the patch panel.

Patch Panel Back

To understand how a patch panel provides for the interconnection of horizontal cabling runs with other networking devices, examine its structure. Rows of pins, much like those in an RJ-45 jack, are located on one side of a patch panel, and just as they are on the jack, the pins are colour-coded.

To make electrical connections to the pins, you must use a punch tool to punch down the wires. Keep in mind that proper wire sequence is critical for best network performance. Therefore, when laying down the wires at the patch panel, make sure the colours of the wires correspond exactly to the colours indicated on the pins. The wire and pin colours are not interchangeable.

Backbone Cabling

The vertical backbone cabling system interconnects telecommunication closets, equipment rooms and external entrance points.

General features of backbone cabling in a structured environment are:

  • Use of an extended star topology
  • The use of recognised and standard media
  • Cable runs meeting distance limitations

Additional Resources

Check the following links for more detailed information on Structured Cabling Standards:

1. Cabling Overview

2. TIA/EIA Standards

3. Siemons Cabling Standards – Very Comprehensive