diff options
Diffstat (limited to 'Bachelor/CCNA4/en_CCNA4_v30/ch4/4_1_1/content.html')
| -rw-r--r-- | Bachelor/CCNA4/en_CCNA4_v30/ch4/4_1_1/content.html | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/Bachelor/CCNA4/en_CCNA4_v30/ch4/4_1_1/content.html b/Bachelor/CCNA4/en_CCNA4_v30/ch4/4_1_1/content.html new file mode 100644 index 0000000..473e327 --- /dev/null +++ b/Bachelor/CCNA4/en_CCNA4_v30/ch4/4_1_1/content.html @@ -0,0 +1,188 @@ +<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>4.1</b></font></td>
+ <td bgcolor="#336666"><img border="0" src="../../images/transdot.gif" width="10" height="1"></td>
+ <td bgcolor="#336666" width="100%"><strong>
+ <font face="Arial" size="2" color="#FFFFFF">ISDN Concepts</font></strong></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">4.1.1</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">Introducing ISDN</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" COLOR="#000000">
+ There are several WAN technologies used to provide network access from
+ remote locations. One of these technologies is ISDN. </font>
+ <font face="Arial" size="2">ISDN can be used as a solution to the low
+ bandwidth problems that small offices or dial-in users have with
+ traditional telephone dial-in services.</font><p>
+
+ <font FACE="Arial" SIZE="2" COLOR="#000000">
+ <font face="Arial" size="2">
+ The traditional PSTN was based on an analog connection between the
+ customer premises and the local
+ exchange, also called the local loop. </font>
+ <img border="0" src="../../images/1.gif" align="absmiddle" width="12" height="12"><font face="Arial" size="2">
+ The analog circuits introduce limitations on the bandwidth that can be
+ obtained on the local loop. Circuit restrictions do not permit analog
+ bandwidths greater than approximately 3000 Hz. ISDN technology
+ permits the use of digital data on the local loop, providing better
+ access speeds for the remote users.
+ <img border="0" src="../../images/2.gif" align="absmiddle" width="12" height="12"></font></font></p>
+ <p>
+
+ <font FACE="Arial" SIZE="2" COLOR="#000000">
+ <font face="Arial" size="2">
+ Telephone companies developed ISDN with the intention of creating a
+ totally digital network. ISDN allows digital signals to be transmitted
+ over existing telephone wiring. This became possible when the
+ telephone company switches were upgraded to handle digital signals.
+ ISDN is generally used for telecommuting and networking small and
+ remote offices into the corporate LAN.</font></font></p>
+ <p>
+ <font face="Arial" size="2" COLOR="#000000">
+ Telephone companies developed ISDN as part of an effort to standardize
+ subscriber services. This included the User-Network Interface (UNI),
+ better known as the local loop.
+ <font face="Arial" size="2">
+ The ISDN standards define the hardware and call setup schemes for
+ end-to-end digital connectivity. These standards help achieve the goal
+ of worldwide connectivity by ensuring that ISDN networks easily
+ communicate with one another. In an ISDN network, the digitizing
+ function is done at the user site rather than the telephone company.</font></font></p>
+ <p>
+ <font face="Arial" size="2" COLOR="#000000">
+ ISDN brings digital connectivity to local sites. The following list
+ provides some of the benefits of ISDN:
+ <img border="0" src="../../images/3.gif" align="absmiddle" width="12" height="12"></font></p>
+ <ul>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000">
+ Carries a variety of user traffic signals, including data, voice,
+ and video </font></li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000">
+ Offers much faster call setup than modem connections </font></li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000">
+ B channels provide a faster data transfer rate
+ than modems </font></li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000">
+ B channels are suitable for negotiated Point-to-Point Protocol (PPP)
+ links </font></li>
+ </ul>
+ <p>
+
+ <font FACE="Arial" SIZE="2" COLOR="#000000">
+ <font face="Arial" size="2">
+ ISDN is a versatile service able to carry voice, video, and data
+ traffic. It is possible to use multiple channels to carry different
+ types of traffic over a single connection.</font></font></p>
+ <p>
+
+ <font face="Arial" size="2" COLOR="#000000">
+ ISDN uses out-of-band signaling, the delta (D channel), for call setup
+ and signaling. To make a normal telephone call, the user dials the
+ number one digit at a time. Once all the numbers are received, the
+ call can be placed to the remote user. ISDN delivers the numbers to
+ the switch at D-channel rates, thus reducing the time it takes to set
+ up the call.</font></p>
+ <p>
+
+ <font face="Arial" size="2" COLOR="#000000">
+ ISDN also provides more bandwidth than a traditional 56 kbps dialup
+ connection. ISDN uses bearer channels, also called B channels, as
+ clear data paths. Each B channel provides 64 kbps of bandwidth. With
+ multiple B channels, ISDN offers more bandwidth for WAN connections
+ than some leased services. An ISDN connection with two B channels
+ would provide a total usable bandwidth of 128 kbps.</font></p>
+ <p>
+ <font face="Arial" size="2" COLOR="#000000">
+ Each ISDN B channel can make a separate serial connection to any other
+ site in the ISDN network. Since PPP operates over both synchronous and
+ asynchronous serial links, ISDN lines can be used in conjunction with
+ PPP encapsulation.</font></p>
+ <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">
+ <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>Integrated Services Digital Network (ISDN)<p>
+ <a target="_blank" href="http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/isdn.htm">
+ http://www.cisco.com/univercd/cc/
+ td/doc/cisintwk/ ito_doc/ isdn.htm</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>
+
+
+ <font face="Arial" size="2"> </font>
+
+ </td>
+ </tr>
+ <tr>
+ <td width="15"> </td>
+ <td>
+
+ </td>
+ </tr>
+ </table>
+
+</body>
+
+</html>
\ No newline at end of file |