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Now, we have configured the static and
default routes (stub networks). It
is often necessary to configure redistribution of static routes
into the backbone dynamic routing protocol to ensure end-to-end
connectivity.
To redistribute those routes, you
need to configure the routes to be redistributed to a dynamic
routing protocol at the core side.
The Figure shows that we use IGRP as
the dynamic routing protocol and redistribute the static routes by
entering the redistribute static command. In this example, the
router advertises that it knows the way to 192.150.42.0.
Dynamic routing can also be used in DDR networks in a number of
ways. Dynamic routing can be used with snapshot routing (as
described in the "Snapshot Routing" section later in this
chapter) to cache routes learned by dynamic routing protocols, thus
allowing the automation of static routing maintenance. Dynamic
routing can also be used as a trigger for routing convergence in
large and complex DDR designs.
When the DDR link is connected,
routing updates will flow to the peer, allowing redundant designs to
converge on the physical connection by redistribution of trigger
routing updates.
The routing protocol selected for DDR
link is typical of a Distance Vector protocol such as RIP, RIP II,
EIGRP, IGRP, or RTMP. Selecting the simplest protocol that meets the
needs of the internetwork design and that is supported by the DDR
routers is generally recommended.
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Lab
Activity |
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You have just installed a new branch office that will use DDR to
dial into your central site. The next step is to configure routing
so the branch office can successfully communicate with the central
site using TCP/IP. You will need to install a default route at the
branch office pointing back at the central site. At the central site
you will need to add a static route for the branch office Ethernet
network pointing back at the branch office router. To ensure that
the branch office can communicate with the rest of the central site,
redistribute the static route to the core network running IGRP.
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