diff options
| 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/ch4/4_1_3/content.html | |
| download | Studium-master.tar.gz Studium-master.tar.bz2 | |
Diffstat (limited to 'Bachelor/CCNA4/en_CCNA4_v30/ch4/4_1_3/content.html')
| -rw-r--r-- | Bachelor/CCNA4/en_CCNA4_v30/ch4/4_1_3/content.html | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/Bachelor/CCNA4/en_CCNA4_v30/ch4/4_1_3/content.html b/Bachelor/CCNA4/en_CCNA4_v30/ch4/4_1_3/content.html new file mode 100644 index 0000000..859f6ce --- /dev/null +++ b/Bachelor/CCNA4/en_CCNA4_v30/ch4/4_1_3/content.html @@ -0,0 +1,215 @@ +<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns="http://www.w3.org/TR/REC-html40">
+
+<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">4</font></b><font face="Arial" size="2" color="#FFFFFF"><b>.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">4.1.3</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">ISDN 3-layer model and
+ protocols</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"> ISDN utilizes a suite of
+ ITU-T standards spanning the physical, data link, and network layers
+ of the OSI reference model:
+ <img border="0" src="../../images/1.gif" align="absmiddle" width="12" height="12"></font><ul>
+ <li>
+
+ <font face="Arial" size="2" COLOR="#000000"> The ISDN BRI and PRI physical layer
+ specifications are defined in ITU-T I.430 and I.431, respectively. </font>
+ </li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> The ISDN data link
+ specification is based on LAPD and is formally specified in the
+ following:
+ <ul>
+ <li>ITU-T Q.920</li>
+ <li>ITU-T Q.921</li>
+ <li>ITU-T Q.922</li>
+ <li>ITU-T Q.923</li></font>
+ </li>
+ </ul></ul>
+
+ <font FACE="Arial" SIZE="2" COLOR="#000000">
+ <font face="Arial" size="2"> The ISDN network layer is defined in ITU-T
+ Q.930, also known as I.450 and ITU-T Q.931, also known as I.451. These
+ standards specify user-to-user, circuit-switched, and packet-switched
+ connections.</font></font></p>
+ <p>
+
+ <font FACE="Arial" SIZE="2" COLOR="#000000">
+ <font face="Arial" size="2"> BRI service is provided over a local
+ copper loop that traditionally carries analog phone service. While
+ there is only one physical path for a BRI, there are three separate
+ information paths, 2B+D. Information from the three channels is
+ multiplexed into the one physical path. </font>
+ </font>
+ </p>
+ <p>
+
+ <font face="Arial" size="2" COLOR="#000000"> ISDN physical layer, or Layer 1, frame
+ formats differ depending on whether the frame is outbound or inbound.
+ If the frame is outbound, it is sent from the terminal to the network.
+ Outbound frames use the TE frame format. If the frame is inbound, it
+ is sent from the network to the terminal. Inbound frames use the NT
+ frame format.
+ <img border="0" src="../../images/2.gif" align="absmiddle" width="12" height="12"></font></p>
+ <p>
+
+ <font face="Arial" size="2">Each frame contains two sample frames each
+ containing the following:</font></p>
+ <ul>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> 8 bits from the B1
+ channel </font>
+ </li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> 8 bits from the B2
+ channel</font></li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> 4 bits from the D channel </font>
+ </li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> 6 bits of overhead </font>
+ </li>
+ </ul>
+ <p>
+
+ <font face="Arial" size="2">ISDN BRI frames contain 48 bits. Four
+ thousand of
+ these frames are transmitted every second. Each B channel, B1and B2,
+ have a capacity of 8*4000 = 64 kbps, while channel D has a capacity of
+ 4*4000 = 16 kbps. This accounts for 144 kbps of the total ISDN BRI
+ physical interface bit rate of 192 kbps. The remainder of the data rate
+ are the overhead bits that are required for transmission.</font></p>
+ <p>
+
+ <font FACE="Arial" SIZE="2" COLOR="#000000">
+ <font face="Arial" size="2"> The overhead bits of an ISDN physical
+ layer frame are used as follows: </font>
+ </font>
+ </p>
+ <ul>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> <b>Framing bit </b>–
+ Provides synchronization</font></li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> <b>Load balancing bit </b>
+ – Adjusts the average bit value</font></li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> <b>Echo of previous D
+ channel bits</b> – Used for contention resolution when several
+ terminals on a passive bus contend for a channel</font></li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> <b>Activation bit</b> –
+ Activates devices</font></li>
+ <li>
+ <font face="Arial" size="2" COLOR="#000000"> <b>Spare bit</b> –
+ Unassigned</font></li>
+ </ul>
+ <p>
+
+ <font face="Arial" size="2">Note that the physical bit rate for the
+ BRI interface is 48*4000 = 192 kbps. The effective rate is 144 kbps = 64 kbps + 64 kbps + 16 kbps (2B+D).</font></p>
+ <p>
+
+ <font face="Arial" size="2">Layer 2 of the ISDN signaling channel is
+ LAPD.</font><font face="Arial" size="2" COLOR="#000000"> LAPD is similar to HDLC. LAPD is used across the D channel to
+ ensure that control and signaling information is received and flows
+ properly.</font></p>
+ <p>
+
+ <font face="Arial" size="2" COLOR="#000000"> The LAPD flag and control fields are
+ identical to those of HDLC.
+ <img border="0" src="../../images/3.gif" align="absmiddle" width="12" height="12"><font face="Arial" size="2"> The LAPD address field is 2 bytes long.
+ The first address field byte contains the service access point
+ identifier (SAPI), which identifies the portal at which LAPD services
+ are provided to Layer 3. The command/response bit (C/R), indicates
+ whether the frame contains a command or a response. The second byte
+ contains the terminal endpoint identifier (TEI). Each piece of
+ terminal equipment on the customer premises needs a unique
+ identifier. The TEI may be statically assigned at installation, or the
+ switch may dynamically assign it when the equipment is started up. If the TEI is statically assigned during installation, the TEI
+ is a number ranging from 0 to 63. Dynamically assigned TEIs range from
+ 64 to 126. A TEI of 127, or all 1s, indicates a broadcast.</font></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 Netowrk (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>
+ </table>
+
+</body>
+
+</html>
\ No newline at end of file |