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                                                                        <p>The first step in locating a wiring closet is to obtain, or create, to-scale floor-plans of the area the network will service. You may use the diagram given in the curriculum. However, you may want to decide the wiring closet location for the actual area of your structured cabling installation project. If floor plan documents are not readily available, it is a worthwhile exercise to have students measure and draw such documents. Many students may show reluctance to drawing. Coach them along, show them some drawing tips, and remind them that sketches and drawings are an important part of the networking professional's skill set. Note the standards for Cat 5 horizontal cable run (shown in the graphic) are 3m maximum for workstation cable, 90m maximum for the horizontal cable, and 6m maximum for the patch cord/jumpers -- this gives us the 100m rule.</p>
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<p>TIA/EIA-568-A specifies that when using an Ethernet star topology, every device that is part of the network must be connected to the hub by a run of horizontal cabling.<img border="0" src="../../../../../CHAPID=knet-v214aCH47508/RLOID=knet-v214aRLO47686/RIOID=knet-v214aRIO121717/knet/v214adataimage1/1.gif" width="12" height="12"> The central point of the star topology, where the hub is located, is called the wiring closet. It helps to think of the hub as the center point of a circle that has lines of horizontal cabling radiating from it, like spokes from the center of a wheel.<img border="0" src="../../../../../CHAPID=knet-v214aCH47508/RLOID=knet-v214aRLO47686/RIOID=knet-v214aRIO121717/knet/v214adataimage2/2.gif" width="12" height="12"></p>
<p>In order to determine the location of a wiring closet, begin by drawing a floor plan of the building (approximately to scale), and adding to it all of the devices that will be connected to the network. Remember that computers are not the only devices that will be connected to the network. There are also printers and file servers to consider.</p>
<p>When this process is complete, the floor plan will be similar to the one shown in Figure <img border="0" src="../../../../../CHAPID=knet-v214aCH47508/RLOID=knet-v214aRLO47686/RIOID=knet-v214aRIO121717/knet/v214adataimage3/3.gif" width="12" height="12">.</p>
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                                    <b>Horizontal Cabling System Structure</b>
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<p>The horizontal cabling system extends from the telecommunications outlet in the work area to the horizontal cross-connect in the telecommunications closet. It includes the telecommunications outlet, the horizontal cable, the mechanical terminations and patch cords or jumpers that comprise the horizontal cross-connect.<img border="0" src="../../../../../CHAPID=knet-v214aCH47508/RLOID=knet-v214aRLO47686/RIOID=knet-v214aRIO121717/knet/v214adataimage4/4.gif" width="12" height="12"></p>
<p>Some points specified for the horizontal cabling subsystem include:</p>
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<li>Recognized Horizontal Cables:<img border="0" src="../../../../../CHAPID=knet-v214aCH47508/RLOID=knet-v214aRLO47686/RIOID=knet-v214aRIO121717/knet/v214adataimage5/5.gif" width="12" height="12">
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<li>4-pair100 Ohm UTP</li>
<li>2 fiber (duplex) 62.5/125 碌m or multimode optical fiber 
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                                                                                <td><span class="note"><b>NOTE:</b>
<p>50/125 碌m multimode fiber will be allowed in ANSI/TIA/EIA-568-B</p>
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                                                                                <td><span class="note"><b>NOTE:</b>
<p>ISO/IEC 11801are 120 惟 UTP and 50/125 碌m multimode optical fiber.</p>
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<li>Multipair and multi-unit cables are allowed, provided that they satisfy the hybrid bundled cable requirements of TIA/EIA-568-A-3.</li>
<li>Grounding must conform to applicable building codes, as well as ANSI/TIA/EIA-697.</li>
<li>A minimum of two telecommunication outlets are required for each individual work area.
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<li>First outlet: 100 惟 UTP (Cat 5e recommended).<img border="0" src="../../../../../CHAPID=knet-v214aCH47508/RLOID=knet-v214aRLO47686/RIOID=knet-v214aRIO121717/knet/v214adataimage5/5.gif" width="12" height="12"></li>
<li>Second outlet: 100 惟 UTP (Cat 5e recommended).</li>
<li>Two-fiber multimode optical fiber either 62.5/125 碌m or 50/ 125 碌m.</li>
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<li>One transition point (TP) is allowed between different forms of the same cable type (for example, where undercarpet cable connects to round cable).
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                                                                        <td><span class="note"><b>NOTE:</b>
<p>The definition provided for a "transition point" on ISO/IEC 11801 is broader than 568-A. It includes transitions to under carpet cabling as well as consolidations point connections.</p>
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<li>50 惟 coax and 150 惟 STP-A cabling is not recommended for new installations.</li>
<li>Additional outlets may be provided. These outlets are in addition to and may not replace the minimum requirements of the standard.</li>
<li>Bridged taps and splices are not allowed for copper-based horizontal cabling. (Splices are allowed for fiber.)
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                                                                        <td><span class="note"><b>NOTE:</b>
<p>In ISO/IEC 11801, the equivalent cabling element to the horizontal cross-connect (HCC) is called the floor distributor (FD).</p>
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<li>Application specific components shall not be installed as part of the horizontal cabling. When needed, they must be placed external to the telecommunications outlet or horizontal cross-connect (for example, splitters and baluns).</li>
<li>The proximity of horizontal cabling to sources of electromagnetic interference (EMI) shall be taken into account.<img border="0" src="../../../../../CHAPID=knet-v214aCH47508/RLOID=knet-v214aRLO47686/RIOID=knet-v214aRIO121717/knet/v214adataimage6/6.gif" width="12" height="12"></li>
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                                        <td valign="middle" width="8%"><img height="23" width="23" src="../../../../../images/ccna/common/icon2.gif"></td><td valign="middle" width="92%"><span class="cstitle">Web Links</span></td>
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                                        <td valign="middle" width="8%">&nbsp;</td><td valign="middle" width="92%"><span class="smtext"><a target="_blank" href="http://www.siemon.com/glossary/definitions.html">Cabling Glossary</a></span></td>
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