5.5 Static and Default Routing
5.5.4 Setting route redistribution
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.

Lab Activity 
  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.