Free Windows Help Tutorials sponsored by inkjet printer cartridges dot org /title> <META HTTP-EQUIV="imagetoolbar" CONTENT="no"> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; CHARSET=ISO 8859-1"> <META name="description" Content="Hundreds of downloadable Windows help tutorials, articles and how-to guides sponsored by inkjet printer cartridges dot org."><style type="text/css">  </style> </head> <body bgcolor=#999999 vlink=blue link=blue> <span name = "INTRA" class="pg" style="top:0px; left:5px; width:714px; height:1010px"></span> <span name = "INTRA" style='top:0px; left:5px; height:1010px; width:714px' class='img'> <img src="pg0001im.png" height = "1010 width = "714" border="0"> </span> <span name = "INTRA" style='top:51px; left:568px' class="ft5"><pre><font face='Helvetica'>Connectivity:Overview</font></pre></span> <span name = "INTRA" style='top:107px; left:100px' class="ft4"><pre><font face='Arial'><b>Understanding</b> <b>TCP/IP</b></font></pre></span> <span name = "INTRA" style='top:213px; left:104px' class="ft2"><pre><font face='Arial'><i><b>TCP/IP,</b></i> <i><b>the</b></i> <i><b>ubiquitous</b></i> <i><b>network</b></i> <i><b>protocol,</b></i> <i><b>is</b></i> <i><b>actually</b></i> <i><b>a</b></i> <i><b>four layer</b></i> <i><b>suite</b></i> <i><b>of</b></i> <i><b>protocols</b></i> <i><b>and</b></i> <i><b>is</b></i></font></pre></span> <span name = "INTRA" style='top:234px; left:109px' class="ft2"><pre><font face='Arial'><i><b>well</b></i> <i><b>worth</b></i> <i><b>gaining</b></i> <i><b>an</b></i> <i><b>understanding</b></i> <i><b>of,</b></i> <i><b>if</b></i> <i><b>only</b></i> <i><b>to</b></i> <i><b>ensure</b></i> <i><b>that</b></i> <i><b>you</b></i> <i><b>set</b></i> <i><b>it</b></i> <i><b>up</b></i> <i><b>in</b></i> <i><b>the</b></i> <i><b>most</b></i></font></pre></span> <span name = "INTRA" style='top:255px; left:274px' class="ft2"><pre><font face='Arial'><i><b>efficient</b></i> <i><b>way</b></i> <i><b>on</b></i> <i><b>your</b></i> <i><b>network.</b></i></font></pre></span> <span name = "INTRA" style='top:287px; left:576px' class="ft1"><pre><font face='Arial'>By Julian Moss</font></pre></span> <span name = "INTRA" style='top:348px; left:77px' class="ft0"><pre><font face='Arial'><b>E</b></font></pre></span> <span name = "INTRA" style='top:352px; left:107px' class="ft1"><pre><font face='Arial'>veryone knows that TCP/IP is a</font></pre></span> <span name = "INTRA" style='top:352px; left:272px' class="ft1"><pre><font face='Arial'>things like routing and reliability.</font></pre></span> <span name = "INTRA" style='top:352px; left:466px' class="ft1"><pre><font face='Arial'>some control fields. There follows the</font></pre></span> <span name = "INTRA" style='top:364px; left:107px' class="ft1"><pre><font face='Arial'>network</font></pre></span> <span name = "INTRA" style='top:364px; left:159px' class="ft1"><pre><font face='Arial'>protocol</font></pre></span> <span name = "INTRA" style='top:364px; left:211px' class="ft1"><pre><font face='Arial'>used</font></pre></span> <span name = "INTRA" style='top:364px; left:246px' class="ft1"><pre><font face='Arial'>on</font></pre></span> <span name = "INTRA" style='top:364px; left:286px' class="ft1"><pre><font face='Arial'>The benefit that the layered proto </font></pre></span> <span name = "INTRA" style='top:364px; left:466px' class="ft1"><pre><font face='Arial'>data, and then a trailer which is simply</font></pre></span> <span name = "INTRA" style='top:376px; left:107px' class="ft1"><pre><font face='Arial'>LANs, WANs and the Internet,</font></pre></span> <span name = "INTRA" style='top:376px; left:272px' class="ft1"><pre><font face='Arial'>col stack gives you is that, if you invent</font></pre></span> <span name = "INTRA" style='top:376px; left:466px' class="ft1"><pre><font face='Arial'>a 32 bit cyclic redundancy check</font></pre></span> <span name = "INTRA" style='top:388px; left:77px' class="ft1"><pre><font face='Arial'>but not everyone who uses it under </font></pre></span> <span name = "INTRA" style='top:388px; left:272px' class="ft1"><pre><font face='Arial'>a new network application or a new</font></pre></span> <span name = "INTRA" style='top:388px; left:466px' class="ft1"><pre><font face='Arial'>(CRC) field. The data portion of an</font></pre></span> <span name = "INTRA" style='top:400px; left:77px' class="ft1"><pre><font face='Arial'>stands how it works. It's possible to use</font></pre></span> <span name = "INTRA" style='top:400px; left:272px' class="ft1"><pre><font face='Arial'>type of hardware, you only need to</font></pre></span> <span name = "INTRA" style='top:400px; left:466px' class="ft1"><pre><font face='Arial'>Ethernet frame must be at least 38</font></pre></span> <span name = "INTRA" style='top:412px; left:77px' class="ft1"><pre><font face='Arial'>TCP/IP with little more than a knowl </font></pre></span> <span name = "INTRA" style='top:412px; left:272px' class="ft1"><pre><font face='Arial'>create a protocol for that application or</font></pre></span> <span name = "INTRA" style='top:412px; left:466px' class="ft1"><pre><font face='Arial'>bytes long, so filler bytes are inserted if</font></pre></span> <span name = "INTRA" style='top:424px; left:77px' class="ft1"><pre><font face='Arial'>edge of how to configure the protocol</font></pre></span> <span name = "INTRA" style='top:424px; left:272px' class="ft1"><pre><font face='Arial'>that hardware: you don't have to re </font></pre></span> <span name = "INTRA" style='top:424px; left:466px' class="ft1"><pre><font face='Arial'>necessary.</font></pre></span> <span name = "INTRA" style='top:436px; left:77px' class="ft1"><pre><font face='Arial'>stack, but a better understanding will</font></pre></span> <span name = "INTRA" style='top:436px; left:272px' class="ft1"><pre><font face='Arial'>write the whole stack.</font></pre></span> <span name = "INTRA" style='top:436px; left:480px' class="ft1"><pre><font face='Arial'>All this means that frames are at</font></pre></span> <span name = "INTRA" style='top:448px; left:77px' class="ft1"><pre><font face='Arial'>give you a clearer picture of what is</font></pre></span> <span name = "INTRA" style='top:448px; left:466px' class="ft1"><pre><font face='Arial'>least 64 bytes long, even if they carry</font></pre></span> <span name = "INTRA" style='top:460px; left:77px' class="ft1"><pre><font face='Arial'>going on in your network and why the</font></pre></span> <span name = "INTRA" style='top:462px; left:272px' class="ft2"><pre><font face='Arial'><i><b>Link</b></i> <i><b>Layer</b></i></font></pre></span> <span name = "INTRA" style='top:460px; left:466px' class="ft1"><pre><font face='Arial'>only one byte of user data: a significant</font></pre></span> <span name = "INTRA" style='top:472px; left:77px' class="ft1"><pre><font face='Arial'>protocol needs to be set up in a particu </font></pre></span> <span name = "INTRA" style='top:472px; left:466px' class="ft1"><pre><font face='Arial'>overhead in some types of application.</font></pre></span> <span name = "INTRA" style='top:484px; left:77px' class="ft1"><pre><font face='Arial'>lar way.</font></pre></span> <span name = "INTRA" style='top:484px; left:286px' class="ft1"><pre><font face='Arial'>TCP/IP is a four layer protocol, as</font></pre></span> <span name = "INTRA" style='top:484px; left:480px' class="ft1"><pre><font face='Arial'>Frames also have a maximum size.</font></pre></span> <span name = "INTRA" style='top:496px; left:91px' class="ft1"><pre><font face='Arial'>The aim of this multi part article is</font></pre></span> <span name = "INTRA" style='top:496px; left:272px' class="ft1"><pre><font face='Arial'>illustrated in Figure 1. The lowest level,</font></pre></span> <span name = "INTRA" style='top:496px; left:466px' class="ft1"><pre><font face='Arial'>Less headers, the maximum size for an</font></pre></span> <span name = "INTRA" style='top:508px; left:77px' class="ft1"><pre><font face='Arial'>to explain the key concepts behind</font></pre></span> <span name = "INTRA" style='top:508px; left:272px' class="ft1"><pre><font face='Arial'>the link layer, is implemented within</font></pre></span> <span name = "INTRA" style='top:508px; left:466px' class="ft1"><pre><font face='Arial'>Ethernet frame is 1492 bytes, which is</font></pre></span> <span name = "INTRA" style='top:520px; left:77px' class="ft1"><pre><font face='Arial'>TCP/IP.</font></pre></span> <span name = "INTRA" style='top:520px; left:272px' class="ft1"><pre><font face='Arial'>the network adapter and its device</font></pre></span> <span name = "INTRA" style='top:520px; left:466px' class="ft1"><pre><font face='Arial'>the</font></pre></span> <span name = "INTRA" style='top:520px; left:493px' class="ft1"><pre><font face='Arial'>maximum</font></pre></span> <span name = "INTRA" style='top:520px; left:555px' class="ft1"><pre><font face='Arial'>transmission</font></pre></span> <span name = "INTRA" style='top:520px; left:628px' class="ft1"><pre><font face='Arial'>unit</font></pre></span> <span name = "INTRA" style='top:532px; left:91px' class="ft1"><pre><font face='Arial'>TCP/IP stands for Transmission</font></pre></span> <span name = "INTRA" style='top:532px; left:272px' class="ft1"><pre><font face='Arial'>driver. Like all the TCP/IP protocols,</font></pre></span> <span name = "INTRA" style='top:532px; left:466px' class="ft1"><pre><font face='Arial'>(MTU) for Ethernet. All link layer pro </font></pre></span> <span name = "INTRA" style='top:544px; left:77px' class="ft1"><pre><font face='Arial'>Control Protocol/Internet Protocol. If</font></pre></span> <span name = "INTRA" style='top:544px; left:272px' class="ft1"><pre><font face='Arial'>it is defined by standards. The stand </font></pre></span> <span name = "INTRA" style='top:544px; left:466px' class="ft1"><pre><font face='Arial'>tocols have an MTU. It is one hardware</font></pre></span> <span name = "INTRA" style='top:556px; left:77px' class="ft1"><pre><font face='Arial'>this leads you to think that it is not just</font></pre></span> <span name = "INTRA" style='top:556px; left:272px' class="ft1"><pre><font face='Arial'>ards for generic Ethernet type net </font></pre></span> <span name = "INTRA" style='top:556px; left:466px' class="ft1"><pre><font face='Arial'>characteristic that the higher level pro </font></pre></span> <span name = "INTRA" style='top:568px; left:77px' class="ft1"><pre><font face='Arial'>one protocol, you're right. In fact, it is</font></pre></span> <span name = "INTRA" style='top:568px; left:272px' class="ft1"><pre><font face='Arial'>works are defined by the IEEE 802</font></pre></span> <span name = "INTRA" style='top:568px; left:466px' class="ft1"><pre><font face='Arial'>tocol needs to be aware of, because</font></pre></span> <span name = "INTRA" style='top:580px; left:77px' class="ft1"><pre><font face='Arial'>not just two protocols, either. TCP/IP</font></pre></span> <span name = "INTRA" style='top:580px; left:272px' class="ft1"><pre><font face='Arial'>Committee: for example, IEEE 802.3</font></pre></span> <span name = "INTRA" style='top:580px; left:466px' class="ft1"><pre><font face='Arial'>larger blocks of data must be frag </font></pre></span> <span name = "INTRA" style='top:592px; left:77px' class="ft1"><pre><font face='Arial'>is a suite of protocols. We'll cover the</font></pre></span> <span name = "INTRA" style='top:592px; left:272px' class="ft1"><pre><font face='Arial'>for Ethernet networks, or IEEE 802.5</font></pre></span> <span name = "INTRA" style='top:592px; left:466px' class="ft1"><pre><font face='Arial'>mented into chunks that fit within the</font></pre></span> <span name = "INTRA" style='top:604px; left:77px' class="ft1"><pre><font face='Arial'>most important ones in the course of</font></pre></span> <span name = "INTRA" style='top:604px; left:272px' class="ft1"><pre><font face='Arial'>for Token Ring networks.</font></pre></span> <span name = "INTRA" style='top:604px; left:466px' class="ft1"><pre><font face='Arial'>MTU and then reassembled on arrival</font></pre></span> <span name = "INTRA" style='top:616px; left:77px' class="ft1"><pre><font face='Arial'>this article.</font></pre></span> <span name = "INTRA" style='top:616px; left:286px' class="ft1"><pre><font face='Arial'>Other link layer protocols that</font></pre></span> <span name = "INTRA" style='top:616px; left:466px' class="ft1"><pre><font face='Arial'>at their destination.</font></pre></span> <span name = "INTRA" style='top:628px; left:272px' class="ft1"><pre><font face='Arial'>could be used include Serial Line IP</font></pre></span> <span name = "INTRA" style='top:642px; left:77px' class="ft2"><pre><font face='Arial'><i><b>Layered</b></i> <i><b>Protocol</b></i></font></pre></span> <span name = "INTRA" style='top:640px; left:272px' class="ft1"><pre><font face='Arial'>(SLIP)</font></pre></span> <span name = "INTRA" style='top:640px; left:313px' class="ft1"><pre><font face='Arial'>or</font></pre></span> <span name = "INTRA" style='top:640px; left:334px' class="ft1"><pre><font face='Arial'>Point to Point</font></pre></span> <span name = "INTRA" style='top:640px; left:413px' class="ft1"><pre><font face='Arial'>Protocol</font></pre></span> <span name = "INTRA" style='top:642px; left:466px' class="ft2"><pre><font face='Arial'><i><b>Network</b></i> <i><b>Layer</b></i></font></pre></span> <span name = "INTRA" style='top:652px; left:272px' class="ft1"><pre><font face='Arial'>(PPP), which are used when connect </font></pre></span> <span name = "INTRA" style='top:664px; left:91px' class="ft1"><pre><font face='Arial'>Like</font></pre></span> <span name = "INTRA" style='top:664px; left:124px' class="ft1"><pre><font face='Arial'>most</font></pre></span> <span name = "INTRA" style='top:664px; left:159px' class="ft1"><pre><font face='Arial'>network</font></pre></span> <span name = "INTRA" style='top:664px; left:211px' class="ft1"><pre><font face='Arial'>protocols,</font></pre></span> <span name = "INTRA" style='top:664px; left:272px' class="ft1"><pre><font face='Arial'>ing to a network over an asynchronous</font></pre></span> <span name = "INTRA" style='top:664px; left:480px' class="ft1"><pre><font face='Arial'>The next layer up from the link layer</font></pre></span> <span name = "INTRA" style='top:676px; left:77px' class="ft1"><pre><font face='Arial'>TCP/IP is a layered protocol. Each</font></pre></span> <span name = "INTRA" style='top:676px; left:272px' class="ft1"><pre><font face='Arial'>dial up link.</font></pre></span> <span name = "INTRA" style='top:676px; left:466px' class="ft1"><pre><font face='Arial'>is called the network layer. The most</font></pre></span> <span name = "INTRA" style='top:688px; left:77px' class="ft1"><pre><font face='Arial'>layer builds upon the layer below it,</font></pre></span> <span name = "INTRA" style='top:688px; left:286px' class="ft1"><pre><font face='Arial'>Since Ethernet is the most common</font></pre></span> <span name = "INTRA" style='top:688px; left:466px' class="ft1"><pre><font face='Arial'>important protocol at this level is IP,</font></pre></span> <span name = "INTRA" style='top:700px; left:77px' class="ft1"><pre><font face='Arial'>adding new functionality. The lowest </font></pre></span> <span name = "INTRA" style='top:700px; left:272px' class="ft1"><pre><font face='Arial'>type of network, we will look at it in a</font></pre></span> <span name = "INTRA" style='top:700px; left:466px' class="ft1"><pre><font face='Arial'>the Internet Protocol. Its job is to send</font></pre></span> <span name = "INTRA" style='top:712px; left:77px' class="ft1"><pre><font face='Arial'>level protocol is concerned purely with</font></pre></span> <span name = "INTRA" style='top:712px; left:272px' class="ft1"><pre><font face='Arial'>bit more detail. The Ethernet protocol</font></pre></span> <span name = "INTRA" style='top:712px; left:466px' class="ft1"><pre><font face='Arial'>packets or datagrams a term which</font></pre></span> <span name = "INTRA" style='top:725px; left:77px' class="ft1"><pre><font face='Arial'>the business of sending and receiving</font></pre></span> <span name = "INTRA" style='top:725px; left:272px' class="ft1"><pre><font face='Arial'>is designed for carrying blocks of data</font></pre></span> <span name = "INTRA" style='top:725px; left:466px' class="ft1"><pre><font face='Arial'>basically means blocks of data from</font></pre></span> <span name = "INTRA" style='top:737px; left:77px' class="ft1"><pre><font face='Arial'>data any data using specific network</font></pre></span> <span name = "INTRA" style='top:737px; left:272px' class="ft1"><pre><font face='Arial'>called frames. A frame consists of a</font></pre></span> <span name = "INTRA" style='top:737px; left:466px' class="ft1"><pre><font face='Arial'>one point to another. It uses the link</font></pre></span> <span name = "INTRA" style='top:749px; left:77px' class="ft1"><pre><font face='Arial'>hardware. At the top are protocols de </font></pre></span> <span name = "INTRA" style='top:749px; left:272px' class="ft1"><pre><font face='Arial'>header containing 48 bit hardware</font></pre></span> <span name = "INTRA" style='top:749px; left:466px' class="ft1"><pre><font face='Arial'>layer protocol to achieve this.</font></pre></span> <span name = "INTRA" style='top:761px; left:77px' class="ft1"><pre><font face='Arial'>signed specifically for tasks like trans </font></pre></span> <span name = "INTRA" style='top:761px; left:272px' class="ft1"><pre><font face='Arial'>destination and source addresses</font></pre></span> <span name = "INTRA" style='top:761px; left:480px' class="ft1"><pre><font face='Arial'>Both the network layer and the link</font></pre></span> <span name = "INTRA" style='top:773px; left:77px' class="ft1"><pre><font face='Arial'>ferring files or delivering email. In</font></pre></span> <span name = "INTRA" style='top:773px; left:272px' class="ft1"><pre><font face='Arial'>(which</font></pre></span> <span name = "INTRA" style='top:773px; left:316px' class="ft1"><pre><font face='Arial'>identify</font></pre></span> <span name = "INTRA" style='top:773px; left:365px' class="ft1"><pre><font face='Arial'>specific</font></pre></span> <span name = "INTRA" style='top:773px; left:413px' class="ft1"><pre><font face='Arial'>network</font></pre></span> <span name = "INTRA" style='top:773px; left:466px' class="ft1"><pre><font face='Arial'>layer are concerned with getting data</font></pre></span> <span name = "INTRA" style='top:785px; left:77px' class="ft1"><pre><font face='Arial'>between are levels concerned with</font></pre></span> <span name = "INTRA" style='top:785px; left:272px' class="ft1"><pre><font face='Arial'>adapters), a 2 byte length field, and</font></pre></span> <span name = "INTRA" style='top:785px; left:466px' class="ft1"><pre><font face='Arial'>from point A to point B. However,</font></pre></span> <span name = "INTRA" style='top:797px; left:466px' class="ft1"><pre><font face='Arial'>whilst the network layer works in the</font></pre></span> <span name = "INTRA" style='top:809px; left:466px' class="ft1"><pre><font face='Arial'>world of TCP/IP, the link layer has to</font></pre></span> <span name = "INTRA" style='top:821px; left:466px' class="ft1"><pre><font face='Arial'>deal with the real world. Everything it</font></pre></span> <span name = "INTRA" style='top:826px; left:102px' class="ft3"><pre><font face='Arial'><i> A</i> <i>router</i> <i>examines</i> <i>every</i> <i>packet,</i> <i>and</i></font></pre></span> <span name = "INTRA" style='top:833px; left:466px' class="ft1"><pre><font face='Arial'>does is geared towards the network</font></pre></span> <span name = "INTRA" style='top:845px; left:466px' class="ft1"><pre><font face='Arial'>hardware it uses.</font></pre></span> <span name = "INTRA" style='top:850px; left:90px' class="ft3"><pre><font face='Arial'><i>compares</i> <i>the</i> <i>destination</i> <i>address</i> <i>with</i> <i>a</i></font></pre></span> <span name = "INTRA" style='top:857px; left:480px' class="ft1"><pre><font face='Arial'>An IP address is a soft address. It</font></pre></span> <span name = "INTRA" style='top:869px; left:466px' class="ft1"><pre><font face='Arial'>is a bit like calling your office block</font></pre></span> <span name = "INTRA" style='top:874px; left:78px' class="ft3"><pre><font face='Arial'><i>table</i> <i>of</i> <i>addresses</i> <i>that</i> <i>it</i> <i>holds</i> <i>in</i> <i>memory. </i></font></pre></span> <span name = "INTRA" style='top:881px; left:466px' class="ft1"><pre><font face='Arial'> Pan Galactic House instead of its</font></pre></span> <span name = "INTRA" style='top:893px; left:466px' class="ft1"><pre><font face='Arial'>real address, 2326 Western Boulevard.</font></pre></span> <span name = "INTRA" style='top:905px; left:466px' class="ft1"><pre><font face='Arial'>The former is no use to the postman</font></pre></span> <span name = "INTRA" style='top:946px; left:52px' class="ft1"><pre><font face='Arial'>Issue 87 (September 1997) page 3</font></pre></span> <span name = "INTRA" style='top:946px; left:610px' class="ft1"><pre><font face='Arial'>File: C04100.1</font></pre></span> <span name = "INTRA" style='top:944px; left:261px' class="ft3"><pre><font face='Arial'><i>PC</i> <i>Network</i> <i>Advisor</i></font></pre></span> <span name = "INTRA" class='nav' style='left: 357px; top: 1010px'><pre><< < GO <a href='page0002.htm'>></a> <a href='page0004.htm'>>></a></pre></span> <span name = "INTRA" style='top:1050px; left:50px' class="ft4"><pre><b><font color="#FF0000" size="3" face="Arial">New!</font><font color="#FF0000" size="3" face="Arial Narrow"> </font><font size="2" face="Arial">The best sites for quality <a href="http://www.inkjet-printer-cartridges.org">inkjet printer cartridges</a> and the best sites for <a href="http://www.cheap-inkjet-cartridges.com">cheap inkjet cartridges</a></font></b></pre></span></body> <span name = "INTRA" style='top:1100px; left:300px' class="ft4"><pre><b><font color="#FF0000" size="3" face="Arial"><a href="../index.html">Windows Help Desk Home</a> </font></b></pre></span></body></html>