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<td bgcolor="#336666"><b><font face="Arial" size="2" color="#FFFFFF">2.2</font></b></td>
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<strong><font face="Arial" size="2" color="#FFFFFF">WAN Technologies</font></strong></td>
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<td bgcolor="#669999" height="25"><b><font face="Arial" size="2" color="#FFFFFF">
2.2.3</font></b></td>
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<td bgcolor="#669999" height="25" width="100%"><strong>
<font face="Arial" size="2" color="#FFFFFF">Leased line</font></strong></td>
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<font face="Arial" size="2">When permanent dedicated connections are
required, leased lines are used with capacities ranging up to 2.5 Gbps.</font><p>
<font face="Arial" size="2">A point-to-point link provides a
pre-established WAN communications path from the customer premises
through the provider network to a remote destination. Point-to-point
lines are usually leased from a carrier and are called leased lines.
Leased lines are available in different capacities.
<img border="0" src="../../images/1.gif" align="absmiddle" width="12" height="12"> These
dedicated circuits are generally priced based on bandwidth required
and distance between the two connected points. Point-to-point links
are generally more expensive than shared services such as Frame Relay.
The cost of leased-line solutions can become significant when they are
used to connect many sites. There are times when cost of the leased
line is outweighed by the benefits. The dedicated capacity gives no
latency or jitter between the endpoints. Constant availability is
essential for some applications such as electronic commerce.</font></p>
<p><font face="Arial" size="2">A router serial port is required for
each leased-line connection. A CSU/DSU and the actual circuit from the service provider are also
required.</font></p>
<p><font face="Arial" size="2">Leased lines are used extensively for
building WANs and give permanent dedicated capacity.
<img border="0" src="../../images/2.gif" align="absmiddle" width="12" height="12"> They have
been the traditional connection of choice but have a number of
disadvantages. WAN traffic is often variable and leased lines have a
fixed capacity. This results in the bandwidth of the line seldom being
exactly what is needed. In addition, each end point would need an
interface on the router which would increase equipment costs. Any changes to the leased line
generally require a site visit by the carrier to change capacity.</font></p>
<p><font face="Arial" size="2">Leased lines
provide direct point-to-point connections between enterprise LANs and connect individual branches to a
packet-switched network. Several connections can be multiplexed over
a leased line, resulting in shorter links and fewer required
interfaces. </font></p>
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<p><font color="#808080">
<a href="javascript:void(0)" onClick="window.open('../../activities/ch02/activity_2_2_3.html','Interactivity','width=740,height=390,toolbar=0,resizable=yes,scrollbars=0,screenX=26,screenY=38,left=26,top=38');">
<img border="0" src="../../images/media_icon.gif" width="25" height="25"></a> <b>
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</font><font FACE="Arial" SIZE="2" COLOR="#808080">
<p>Checkbox: WAN Technologies Leased Lines</p>
<p>Upon completing this activity, the student
will be able to identify the characteristics associated with a
leased line connection.</p>
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