Information Technology Reference
In-Depth Information
remote site because the hub is the only route used to reach all other sites. Static routes are
also used at network boundaries (Internet or partners) where routing information is not
exchanged. These static routes are then redistributed into the internal dynamic routing
protocol used.
Figure 10-1 shows a hub-and-spoke WAN where static routes are defined in the remote
WA N r o u t e r s b e c a u s e n o r o u t i n g p r o t o c o l s a r e c o n f i g u r e d . T h i s s e t u p e l i m i n a t e s r o u t i n g
protocol traffic on the low-bandwidth WAN circuits.
Static Routes Configured on
Slow Speed WAN Links
Dynamic Routing
64 k
128 k
56 k
Figure 10-1
Static Routes in a Hub-and-Spoke Network
Routing protocols dynamically determine the best route to a destination. When the net-
work topology changes, the routing protocol adjusts the routes without administrative in-
tervention. Routing protocols use a metric to determine the best path toward a destination
network. Some use a single measured value such as hop count. Others compute a metric
value using one or more parameters. Routing metrics are discussed later in this chapter.
The following is a list of dynamic routing protocols:
RIPv1
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RIPv2
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IGRP
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EIGRP
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OSPF
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IS-IS
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RIPng
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OSPFv3
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