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			Home &gt; Graph Theory: Networking
					&gt; Telephone Networks
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    <div id="content"><h1>Costs</h1>
				<p>
				The simplicity of the telephone exchange protocol comes at a price:
				</p>
				<ol><li>
					If a switch in the core crashes, the routing protocol 
					<b>doesn't know how to find an alternative path</b>. 
					Therefore, to make the system as a whole reliable,
					<b>every switch must be reliable</b>.
					</li><li>
					Requiring every pair of switches to be connected by a one-hop logical trunk makes for 
					a network that is expensive to create and to maintain.
					</li></ol>
				<p>
				An alternative would be to develop a network where sophisticated
				routing algorithms lower the requirements for connectivity by allowing
				the removal of some of the direct links.
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