diff options
Diffstat (limited to 'Bachelor/CCNA4/en_CCNA4_v30/ch1/1_1_3/content.html')
| -rw-r--r-- | Bachelor/CCNA4/en_CCNA4_v30/ch1/1_1_3/content.html | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/Bachelor/CCNA4/en_CCNA4_v30/ch1/1_1_3/content.html b/Bachelor/CCNA4/en_CCNA4_v30/ch1/1_1_3/content.html new file mode 100644 index 0000000..8eb1c1c --- /dev/null +++ b/Bachelor/CCNA4/en_CCNA4_v30/ch1/1_1_3/content.html @@ -0,0 +1,178 @@ +<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"><font face="Arial" size="2" color="#FFFFFF"><b>1.1</b></font></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">Scaling Networks with NAT and
+ PAT</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">
+ 1.1.3</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%"><b>
+ <font face="Arial" size="2" color="#FFFFFF">Major NAT and PAT features</font></b></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">
+ NAT translations can be used for a variety of purposes and can be
+ either dynamically or statically assigned. Static NAT is designed to
+ allow one-to-one mapping of local and global addresses. This is
+ particularly useful for hosts which must have a consistent address
+ that is accessible from the Internet. Such hosts may be enterprise
+ servers or networking devices.<p>Dynamic NAT is designed to map a
+ private IP address to a public address. Any IP address from a pool of
+ public IP addresses is assigned to a network host. Overloading, or
+ Port Address Translation (PAT), maps multiple private IP addresses to
+ a single public IP address. Multiple addresses can be mapped to a
+ single address because each private address is tracked by a port
+ number.
+ <font face="Arial" size="2" COLOR="#000000">
+ <img border="0" src="../../images/1.gif" align="absmiddle" width="12" height="12"></font><p>PAT uses
+ unique source port numbers on the inside global IP address to
+ distinguish between translations.
+ <font face="Arial" size="2" COLOR="#000000">
+ <img border="0" src="../../images/2.gif" align="absmiddle" width="12" height="12"> </font>The port
+ number is encoded in 16 bits. The total number of internal addresses
+ that can be translated to one external address could theoretically be
+ as high as 65,536 per IP address. Realistically, the number of ports
+ that can be assigned a single IP address is around 4000. PAT will attempt to
+ preserve the original source port. If this source port is already
+ used, PAT will assign the first available port number starting from
+ the beginning of the appropriate port group 0-511, 512-1023, or
+ 1024-65535. When there are no more ports available and there is more
+ than one external IP address configured, PAT moves to the next IP
+ address to try to allocate the original source port again. This
+ process continues until it runs out of available ports and external IP
+ addresses.<p>NAT offers the following benefits:<ul>
+ <li>Eliminates reassigning each host a new IP address when
+ changing to a new ISP. NAT eliminates the need to readdress all
+ hosts that require external access, saving time and money.</li>
+ <li>Conserves addresses through application port-level
+ multiplexing. With PAT, internal hosts can share a single public
+ IP address for all external communications. In this
+ type of configuration, very few external addresses are required to
+ support many internal hosts, thereby conserving IP addresses.</li>
+ <li>Protects network security. Because private networks do not
+ advertise their addresses or internal topology, they remain
+ reasonably secure when used in conjunction with NAT to gain
+ controlled external access.</li>
+ </ul></font></p>
+ <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">
+ <a href="javascript:void(0)" onClick="window.open('../../activities/ch01/activity_1_1_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/media_icon.gif" width="25" height="25"></a> <b>
+ <a onClick="window.open('../../activities/ch01/activity_1_1_3.html','Interactivity','width=740,height=390,toolbar=0,resizable=yes,scrollbars=0,screenX=26,screenY=38,left=26,top=38');" href="javascript:void(0)">Interactive Media Activity</a></b></font></p>
+ </font><font FACE="Arial" SIZE="2" COLOR="#808080">
+ <p>Drag and Drop: Network Address Translation with Overload
+ (NAT)</p>
+ <p>When the student has completed this activity, the student
+ will be able to identify the IP address and port translations
+ that occur when using PAT.</p>
+ </font><font FACE="Arial" SIZE="2" COLOR="#000000">
+ <p><IMG alt="" height="2" width="1" src="../../images/s.gif"></p></TD>
+ </TR>
+ </TABLE>
+ </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>About NAT<p>
+ <a target="_blank" href="http://www.homenethelp.com/web/explain/about-NAT.asp">
+ http://www.homenethelp.com/web/explain/ about-NAT.asp</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>
+
+ </td>
+ </tr>
+ </table>
+
+</body>
+
+</html>
\ No newline at end of file |