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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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Hubs do not amplify. They regenerate and retime signals. This is because technically amplification refers to increasing the amplitude of an analog signal. The hub does not amplify incoming bits (which may have distortions and noise on them), but rather it detects (hopefully correctly) incoming ones and zeros and regenerates without any noise or distortion for the next leg in the journey across the network. Hubs are active Layer 1 devices because they involve the transfer of energy to the signal (they require energy to perform their function).</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>Multiport repeaters combine connectivity with the amplifying and retiming properties of repeaters. It is typical to see four, eight, 12, and up to 24, ports on multiport repeaters. This allows many devices to be cheaply and easily interconnected. Multiport repeaters are often called hubs, instead of repeaters, when referring to the devices that serve as the center of a star topology network. Hubs are very common internetworking devices. Since the typical unmanaged hub only requires power and plugged in RJ-45 jacks, they are great for setting up a network quickly. Like the repeaters on which they are based, they only deal with bits, and are Layer 1 devices.</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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