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<html> <head> <meta content="en-us" http-equiv="Content-Language"> <meta content="text/html; charset=UTF-8" http-equiv="Content-Type"> <link type="text/css" rel="stylesheet" href="../../../../../css/ccna.css"> <script src="../../../../../js/framesetHelper.js" language="JavaScript"></script><script language="JavaScript"> window.scrollTo(0,0); function newPage(pageID) { alert("COMMING SOON!!\nThis feature is currently in development."); } function launchMoreInfo(oid) { dash = oid.indexOf('-'); sub1 = oid.substring(0,dash); sub2 = oid.substring(dash+1); // this is an URL base on the // system that generated the static // download of the curriculum. httpref = "http://nomar.sdf.cisco.com/servlet/org.cli.delivery.rendering.servlet.MIServlet/Static=true,LMSID=DTUI,Engine=dynamic,Theme=cnamstheme,Style=ccna,Language=en,Version=2,RootID=knet-v214aCV47051/CHAPID=null/RLOID=null/RIOID=null/"; newref = httpref + sub1 +"/"+ sub2 +"/moreinfoframeset.html"; //alert("new newref :\n" + newref); window.open(newref,'MoreInfo','toolbar=no,status=yes,menubar=no,location=no,scrollbars=yes,height=442,width=756,left=20,top=20,resizable=yes') } function launchContentResource(contentID) { top.currentSupport = 0; 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eval('top.frames.main_frame.location.href="'+ContentRef+'referencecontroller_crf.html"'); chapter = "knet-v214aCH47505"; ch_dash = chapter.indexOf('-'); ch_sub1 = chapter.substring(0,ch_dash); ch_sub2 = chapter.substring(ch_dash+1); params = "CHAPID=" + chapter + "/RLOID=" + "knet-v214aRLO47653" + "/RIOID=" + "knet-v214aRIO121176"; returnRef = "../../../../../"+ params + "/"+ ch_sub1 +"/"+ ch_sub2 +"/pageframeset.html"; top.prevPage = returnRef; } function launchFile(filepath) { newWindow = window.open(filepath,"","top=70,left=120,width="+(screen.width*.50)+",height="+(screen.height*.50)+",resizable=yes,scrollbars=yes,toolbar=yes,menubar=yes,status=yes"); /* if (is.ie && filepath.lastIndexOf(".pdf") != -1) { pageTimer = setInterval("winLoadCheck()", 1000); } */ } function winLoadCheck() { if (newWindow.document.readyState == 'complete') { clearInterval(pageTimer); newWindow.location.reload(); } } // BrowserCheck Object // provides most commonly needed browser checking variables // 19990326 // Copyright (C) 1999 Dan Steinman // Distributed under the terms of the GNU Library General Public License // Available at http://www.dansteinman.com/dynapi/ function BrowserCheck() { var b = navigator.appName if (b=="Netscape") this.b = "ns" else if (b=="Microsoft Internet Explorer") this.b = "ie" else this.b = b this.v = parseInt(navigator.appVersion) this.ns = (this.b=="ns" && this.v>=4) this.ns4 = (this.b=="ns" && this.v==4) this.ns5 = (this.b=="ns" && this.v==5) this.ie = (this.b=="ie" && this.v>=4) this.ie4 = (navigator.userAgent.indexOf('MSIE 4')>0) this.ie5 = (navigator.appVersion.indexOf('MSIE 5.0')>0) this.ie55 = (navigator.appVersion.indexOf('MSIE 5.5')>0) if (this.ie5) this.v = 5 this.min = (this.ns||this.ie) } // automatically create the "is" object is = new BrowserCheck()</script> </head> <body onLoad="window.focus();" alink="#000000" vlink="#000000" link="#000000" bgcolor="#E7E7E7" background="../../../../../images/ccna/common/bg.gif"> <table width="100%" cellspacing="0" cellpadding="2" border="0"><tr> <td bgcolor="#000000"><img height="1" width="2" border="0" src="../../../../../images/ccna/common/transdot.gif"></td><td class="rlohdr"><img height="1" width="2" border="0" src="../../../../../images/ccna/common/transdot.gif"></td><td valign="top" class="rlohdr">5.2</td><td width="100%" class="rlohdr"> <table width="90%" cellpadding="0" cellspacing="0" border="0"> <tr> <td class="rlohdr">Cable Specification and Termination</td> </tr> </table> </td> </tr> <tr> <td bgcolor="#000000"><img height="1" width="2" border="0" src="../../../../../images/ccna/common/transdot.gif"></td><td class="riohdr"><img height="1" width="2" border="0" src="../../../../../images/ccna/common/transdot.gif"></td><td valign="top" class="riohdr">5.2.3</td><td width="100%" class="riohdr"> <table width="90%" cellpadding="0" cellspacing="0" border="0"> <tr> <td class="riohdr">Explain the details of TIA/EIA-568-A</td> </tr> </table> </td> </tr> <tr> <td colspan="4"> <table width="90%" cellspacing="0" cellpadding="0" border="0"> <tr> <td class="smtext"> <p> </p><table cellpadding="0" cellspacing="0" width="100%" border="0" xmlns:java="http://xml.apache.org/xslt/java"> <tr> <td width="100%"><img height="10" width="1" border="0" src="../../../../../images/ccna/common/transdot.gif"></td> </tr> <tr> <td width="100%"> <table bgcolor="#000000" bordercolor="#000000" cellspacing="0" bordercolorlight="#000000" width="100%" border="0"> <tr> <td width="100%"> <table bgcolor="#FFFFFF" cellspacing="0" cellpadding="2" width="100%" border="0"> <tr> <td valign="middle"><img height="22" width="22" border="0" src="../../../../../images/ccna/common/inotes.gif"></td><td valign="middle"><span class="cstitle">Instructor Note</span></td> </tr> <tr> <td valign="top"> </td><td valign="top"><span class="cstext"> <p>The purpose of this target indicator is to introduce a common (in the US) wiring standard.</p> <p>This TI relates to the Layer 1 part of CCNA Certification Exam Objective #1.</p> </span></td> </tr> </table> </td> </tr> </table> </td> </tr> </table><p>The TIA/EIA standards address six elements of the LAN cabling process. These are:</p><ul type="disc"><li>Horizontal cabling</li><li>Telecommunications closets</li><li>Backbone cabling</li><li>Equipment rooms</li><li>Work areas</li><li>Entrance facilities</li></ul><p>This lesson will focus on TIA/EIA-568-A standards for horizontal cabling, which defines horizontal cabling as cabling that runs from a telecommunications outlet to a horizontal cross-connect. It includes the networking medium that runs along a horizontal pathway, the telecommunications outlet or connector, the mechanical terminations in the wiring closet, and the patch cords or jumpers in the wiring closet. In short, horizontal cabling includes the networking media that is used in the area that extends from the wiring closet to a workstation.</p><p>TIA/EIA-568-A contains specifications governing cable performance. It calls for running two cables, one for voice and one for data, to each outlet. Of the two cables, the one for voice must be four-pair UTP. The TIA/EIA-568-A standard specifies five categories in the specifications. These are category 1 (CAT 1), category 2 (CAT 2), category 3 (CAT 3), category 4 (CAT 4), and category 5 (CAT 5) cabling. Of these, only CAT 3, CAT 4, and CAT 5 are recognized for use in LANs. Of these three categories, CAT 5 is the one most frequently recommended and implemented in installations today.</p><p>Students have studied the networking media that are recognized for these categories:</p><ul type="disc"><li>Shielded twisted-pair</li><li>Unshielded twisted-pair</li><li>Fiber-optic cable</li><li>Coaxial cable</li></ul><p>For shielded twisted-pair cable, the TIA/EIA-568-A standard calls for two pair 150 ohm cable. For unshielded-twisted pair, the standard calls for four pair 100 ohm cable. For fiber-optic, the standard calls for two fibers of 62.5/125 multimode cable. Although 50 ohm coaxial cable is a recognized type of networking media in TIA/EIA-568-A, it is not recommended for new installations. This type of coaxial cable is expected to be removed from the list of recognized networking media the next time this standard is revised.</p><p>For the horizontal cabling component, TIA/EIA-568A requires a minimum of two telecommunications outlets or connectors at each work area. This telecommunications outlet/connector is supported by two cables. The first is a four-pair 100 ohm CAT 3 or higher UTP cable along with its appropriate connector. The second can be any one of the following:</p><ul type="disc"><li>Four-pair 100 ohm unshielded twisted-pair cable and its appropriate connector</li><li>150 ohm shielded twisted-pair cable and its appropriate connector</li><li>Coaxial cable and its appropriate connector</li><li>Two-fiber 62.5/125 脗碌 optical fiber cable and its appropriate connector</li></ul><p>According to TIA/EIA-568-A, the maximum distance for cable runs in horizontal cabling is 90 meters (m). This is true for all types of CAT 5 UTP recognized networking media. The standard also specifies that patch cords or cross-connect jumpers located at the horizontal cross-connect cannot exceed 6 m in length. TIA/EIA-568-A also allows 3 m for patch cords that are used to connect equipment at the work area. The total length of the patch cords and cross-connect jumpers used in the horizontal cabling cannot exceed 10 m. A final specification for horizontal cabling contained in TIA/EIA-568-A requires that all grounding and bonding must conform to TIA/EIA-607. It must also conform to any other applicable codes.</p><p>The latest industry standards being developed are for Cat 5e, Cat 6, and Cat 7 cabling, all of which offer improvements over Cat 5.</p><p> <a href="#" onClick="window.open('../../../../../static/cabling/index.html','CablingStandards','width=742,height=390,toolbar=0,scrollbars=0,left=26,top=38');void(null);">Upcoming Changes in Cabling Standards</a> </p></td> </tr> </table> </td> </tr></table> <p> </p> <table width="100%" cellspacing="0" cellpadding="2" border="0" valign="bottom"> <tr> <td></td> </tr> </table> </body></html>⌨️ 快捷键说明
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