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| author | Sven Eisenhauer <sven@sven-eisenhauer.net> | 2023-11-10 15:11:48 +0100 |
|---|---|---|
| committer | Sven Eisenhauer <sven@sven-eisenhauer.net> | 2023-11-10 15:11:48 +0100 |
| commit | 33613a85afc4b1481367fbe92a17ee59c240250b (patch) | |
| tree | 670b842326116b376b505ec2263878912fca97e2 /Bachelor/CCNA4/en_CCNA4_v30/ch5/5_2_3/content.html | |
| download | Studium-master.tar.gz Studium-master.tar.bz2 | |
Diffstat (limited to 'Bachelor/CCNA4/en_CCNA4_v30/ch5/5_2_3/content.html')
| -rw-r--r-- | Bachelor/CCNA4/en_CCNA4_v30/ch5/5_2_3/content.html | 171 |
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diff --git a/Bachelor/CCNA4/en_CCNA4_v30/ch5/5_2_3/content.html b/Bachelor/CCNA4/en_CCNA4_v30/ch5/5_2_3/content.html new file mode 100644 index 0000000..3b8a71a --- /dev/null +++ b/Bachelor/CCNA4/en_CCNA4_v30/ch5/5_2_3/content.html @@ -0,0 +1,171 @@ +<html>
+
+<head>
+<meta http-equiv="Content-Language" content="en-us">
+<meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
+<title>Content</title>
+<base target="_self">
+</head>
+
+<body background="../../images/bg.gif" topmargin="0" leftmargin="0" marginheight="0" marginwidth="0" onLoad="window.focus();" link="#808080" vlink="#808080" alink="#808080">
+
+<table border="0" cellpadding="0" cellspacing="0" width="100%">
+ <tr>
+ <td bgcolor="#336666" width="18" valign="top">
+ <img border="0" src="../../images/content_lines.gif" width="16" height="25">
+ <img border="0" src="../../images/transdot.gif" width="2" height="1"></td>
+ <td bgcolor="#336666"><b><font face="Arial" size="2" color="#FFFFFF">5</font></b><font face="Arial" size="2" color="#FFFFFF"><b>.</b></font><b><font face="Arial" size="2" color="#FFFFFF">2</font></b></td>
+ <td bgcolor="#336666"><img border="0" src="../../images/transdot.gif" width="10" height="1"></td>
+ <td bgcolor="#336666" width="100%"><b>
+ <font face="Arial" size="2" color="#FFFFFF">Configuring Frame Relay</font></b></td>
+ <td width="9" bgcolor="#336666"> </td>
+ </tr>
+ <tr>
+ <td bgcolor="#669999" height="25" width="18"> </td>
+ <td bgcolor="#669999" height="25"><b>
+ <font face="Arial" size="2" color="#FFFFFF">5.2.3</font></b></td>
+ <td bgcolor="#669999"><img border="0" src="../../images/transdot.gif" width="10" height="1"></td>
+ <td bgcolor="#669999" height="25" width="100%"><strong>
+ <font face="Arial" size="2" color="#FFFFFF">Reachability issues with routing
+ updates in NBMA</font></strong></td>
+ <td bgcolor="#669999" height="25" width="9"> </td>
+ </tr></table>
+
+<table border="0" cellpadding="0" cellspacing="0" width="95%" bordercolor="#111111">
+ <tr>
+ <td width="15"></td>
+ <td>
+
+ <font FACE="Arial" SIZE="2">By default, a Frame Relay network provides non-broadcast multi-access (NBMA)
+ connectivity between remote sites. An NBMA environment is viewed like other
+ multiaccess media environments, such as Ethernet, where all the routers are
+ on the same subnet. However, to reduce cost, NBMA clouds are usually built
+ in a hub-and-spoke topology. With a hub-and-spoke topology, the physical
+ topology does not provide the multi-access capabilities that Ethernet does.
+ <img border="0" src="../../images/1.gif" align="absmiddle" width="12" height="12"> The physical
+ topology consists of multiple PVCs.
+ <p>A Frame Relay NBMA topology may cause two problems:</p>
+ <ul>
+ <li>Reachability issues regarding routing updates </li>
+ <li>The need to replicate broadcasts on each PVC when a physical
+ interface contains more than one PVC</li>
+ </ul>
+ <p>Split-horizon updates reduce routing loops by not allowing a routing
+ update received on one interface to be forwarded out the same interface. If
+ Router B, a spoke router, sends a broadcast routing update to Router A, the
+ hub router, and Router A has multiple PVCs over a single physical interface,
+ then Router A cannot forward that routing update through the same physical
+ interface to other remote spoke routers. If split-horizon is disabled, then the
+ routing update can be forwarded out the same physical interface from which
+ it came. Split-horizon is not a problem when there is a single PVC on a
+ physical interface. This would be a point-to-point Frame Relay connection.
+ <img border="0" src="../../images/2.gif" align="absmiddle" width="12" height="12"></p>
+ <p>Routers that support multiple connections over a single physical
+ interface have many PVCs that terminate in a single router. This router must
+ replicate broadcast packets such as routing update broadcasts, on each PVC,
+ to the remote routers. The replicated broadcast packets can consume
+ bandwidth and cause significant latency to user traffic. It might seem
+ logical to turn off split-horizon to resolve the reachability issues caused
+ by split-horizon. However, not all network layer protocols allow
+ split-horizon to be disabled and disabling split-horizon increases the
+ chances of routing loops in any network.</p>
+ <p>One way to solve the split-horizon problem is to use a fully meshed
+ topology. However, this will increase the cost because more PVCs are
+ required. The preferred solution is to use subinterfaces. </p>
+ <p>
+
+
+ <TABLE bgcolor="#669999" width="95%" cellspacing="0" cellpadding="0" border="0">
+ <TR>
+ <TD width="5">
+ <img border="0" src="../../images/lab_toplft.gif" width="116" height="23"></TD>
+ <TD>
+ <IMG alt="" height="1" width="3" src="../../images/s.gif"></TD><TD align="right" valign="top">
+ <IMG alt="" src="../../images/corner_ur_7.gif" width="7" height="7"></TD>
+ </TR>
+ </TABLE>
+
+ <TABLE bgcolor="#B0AFAF" width="95%" cellspacing="0" cellpadding="0" border="0">
+ <TR>
+ <TD>
+ <TABLE width="100%" cellpadding="2" cellspacing="0" border="0" bordercolor="#111111">
+ <TR>
+ <TD bgcolor="#ffffff" width="15"> </TD>
+ <TD bgcolor="#ffffff"><font FACE="Arial" SIZE="2" COLOR="#000000">
+ <p><font color="#808080">
+
+ <a href="javascript:void(0)" onClick="window.open('../../elabs/mod05/elab_5_2_3/elab5_2_3.html','Interactivity','width=740,height=390,toolbar=0,resizable=yes,scrollbars=0,screenX=26,screenY=38,left=26,top=38');">
+ <img border="0" src="../../images/lab_icon.gif" width="25" height="25"><b></a>
+ <a href="javascript:void(0)" onClick="window.open('../../elabs/mod05/elab_5_2_3/elab5_2_3.html','Interactivity','width=740,height=390,toolbar=0,resizable=yes,scrollbars=0,screenX=26,screenY=38,left=26,top=38');">Lab Activity</a></b></font></p>
+ </font><font FACE="Arial" SIZE="2" COLOR="#808080">
+ <p>e-Lab Activity:
+ </font>
+ <font FACE="Arial" SIZE="2" COLOR="#808080">
+ Configuring Frame Relay Subinterfaces</font></p>
+
+ <font FACE="Arial" SIZE="2">
+ <font FACE="Arial" SIZE="2" COLOR="#808080">
+ <p>In this activity, the student will configure three routers in
+ a full-mesh Frame Relay network.</p>
+
+ <p>
+ <IMG alt="" height="2" width="1" src="../../images/s.gif"></p>
+ </TD>
+ </TR>
+ </TABLE>
+ </TD>
+ </TR>
+ </TABLE>
+
+
+ <TABLE bgcolor="#B0AFAF" width="95%" border="0" cellspacing="0" cellpadding="0">
+ <TR>
+ <TD valign="top">
+ <TABLE bgcolor="#669999" width="100%" cellspacing="0" cellpadding="0" border="0">
+ <TR>
+ <TD width="5">
+ <img border="0" src="../../images/lab_toplft.gif" width="116" height="23"></TD>
+ <TD><IMG alt="" height="1" width="3" src="../../images/s.gif"></TD><TD align="right" valign="top">
+ <IMG alt="" src="../../images/corner_ur_7.gif" width="7" height="7"></TD>
+ </TR>
+ </TABLE>
+
+ <TABLE bgcolor="#B0AFAF" width="100%" cellspacing="0" cellpadding="0" border="0">
+ <TR>
+ <TD>
+ <TABLE width="100%" cellpadding="2" cellspacing="0" border="0" bordercolor="#111111">
+ <TR>
+ <TD bgcolor="#ffffff" width="15"> </TD>
+ <TD bgcolor="#ffffff"><font FACE="Arial" SIZE="2" COLOR="#000000">
+ <p><font color="#808080">
+ <img border="0" src="../../images/links_icon.gif" width="25" height="25">
+ <b>Web Links</b></font></p>
+ </font><font FACE="Arial" SIZE="2" COLOR="#808080">
+
+ <p>Problems with Running OSPF in NBMA Mode over Frame Relay<p>
+ <a target="_blank" href="http://www.cisco.com/en/US/tech/tk826/tk365/technologies_tech_note09186a0080094051.shtml">
+ http://www.cisco.com/en/US/tech/
+ tk826/tk365/technologies_tech_
+ note09186a0080094051.shtml</a></font></p>
+
+ <p>
+ <IMG alt="" height="2" width="1" src="../../images/s.gif"></p>
+ </TD>
+ </TR>
+ </TABLE>
+ </TD>
+ </TR>
+ </TABLE>
+ </TD>
+ </TR>
+ </TABLE><p>
+
+ </p>
+ </font>
+ </td>
+ </tr>
+ </table>
+
+</body>
+
+</html>
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