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			Home &gt; Graph Theory: Networking
					&gt; The Internet
					&gt; Overview</div>
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        <a class="toc_link" href="">Routing</a>
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        <a class="toc_link" href="page21.xml">Designing A Routing Protocol</a>
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        <a class="toc_link" href="page30.xml">Distance-Vector Routing</a>
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    <div id="content"><h1>Overview</h1>
				<h2>Internet Routing: An Overview</h2>
				<p>
				We have seen that telephone networks are notable for the
				predictability of their traffic flows and their relatively small
				cores.
				</p>
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				The environment of the Internet is very different:
				</p>
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					Links and routers are unreliable.
					</li><li>
					Alternative paths are scarce
					</li><li>
					Traffic patterns change unpredictably within minutes.
					</li></ol>
				<p>
				Routing strategies in such an environment therefore have to be much
				more tolerant of changes in the network than are the strategies for
				telephone networks.  The two fundamental routing algorithms in
				packet-switched networks (the Internet and ATM networks) are:
				</p>
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					Distance-Vector (based on the <a href="bellman_theory.html">Bellman-Ford
					Algorithm</a>).
					</li><li>
					Link-State (based on <a href="dijkstra_theory.html">Dijkstra's
					Algorithm</a>).
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				<p>
				We will examine each of these routing strategies in turn.
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