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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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For example, use five students: one student in the middle playing the role of a switch, two students on the left portraying hosts on one subnet, and two students on the right portraying host on a different subnet. Label the hosts with MAC addresses A, B, C, D. Have the switch create a switching table, which shows each switch interface and the MAC addresses of the hosts that are accessible through that interface. Have the hosts send frames to each other and have the switch person explain their filtering and forwarding decisions.</p> <p>Switching is an extremely important topic on the CCNA Certification Exam. This TI relates to CCNA Certification Exam Objectives #46 through #60.</p> </span></td> </tr> </table> </td> </tr> </table> </td> </tr> </table><p>LAN switches are considered multiport bridges with no collision domain. You can think of each switch port as a micro bridge. This process is called microsegmentation.<img border="0" src="../../../../../CHAPID=knet-v214aCH47507/RLOID=knet-v214aRLO47675/RIOID=knet-v214aRIO121646/knet/v214adataimage1/1.gif" width="12" height="12"> Data is exchanged at high speeds by switching the frame to its destination. By reading the destination MAC address Layer 2 information, switches can achieve high speed data transfers, much like a bridge does. The frame is sent to the port of the receiving station prior to the entire frame entering the switch. This leads to low latency levels and a high rate of speed for frame forwarding.<img border="0" src="../../../../../CHAPID=knet-v214aCH47507/RLOID=knet-v214aRLO47675/RIOID=knet-v214aRIO121646/knet/v214adataimage2/2.gif" width="12" height="12"><img border="0" src="../../../../../CHAPID=knet-v214aCH47507/RLOID=knet-v214aRLO47675/RIOID=knet-v214aRIO121646/knet/v214adataimage3/3.gif" width="12" height="12"></p><p>Ethernet switching increases the bandwidth available on a network. It does this by creating dedicated network segments, or point-to-point connections, and connecting these segments in a virtual network within the switch. This virtual network circuit exists only when two nodes need to communicate. This is called a <i>virtual circuit</i> because it exists only when needed, and is established within the switch.</p><p>Even though the LAN switch reduces the size of collision domains, all hosts connected to the switch are still in the same broadcast domain. Therefore, a broadcast from one node will still be seen by all other nodes connected through the LAN switch.<img border="0" src="../../../../../CHAPID=knet-v214aCH47507/RLOID=knet-v214aRLO47675/RIOID=knet-v214aRIO121646/knet/v214adataimage4/4.gif" width="12" height="12"></p><p>Switches are data link layer devices that, like bridges, enable multiple physical LAN segments to be interconnected into single larger network. Similar to bridges, switches forward and flood traffic based on MAC addresses. Because switching is performed in hardware instead of in software, it is significantly faster. You can think of each switch port as a micro bridge. This process is called <i>microsegmentation</i>.<img border="0" src="../../../../../CHAPID=knet-v214aCH47507/RLOID=knet-v214aRLO47675/RIOID=knet-v214aRIO121646/knet/v214adataimage1/1.gif" width="12" height="12"> Thus each switch port acts as a separate bridge and gives the full bandwidth of the medium to each host.</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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