Cisco IOS Cookbook, 2nd Edition

Creating a Default Route in RIP

Problem

You want RIP to propagate a default route.

Solution

There are two ways to get RIP to propagate a default route. The preferred method is using the default-information originate command as follows:

Router1#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#ip route 0.0.0.0 0.0.0.0 172.25.1.1
Router1(config)#router rip
Router1(config-router)#default-information originate
Router1(config-router)#end
Router1#

In simple situations, you can accomplish the same thing by just redistributing a static route:

Router1#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#ip route 0.0.0.0 0.0.0.0 172.25.1.1
Router1(config)#access-list 7 permit 0.0.0.0
Router1(config)#router rip
Router1(config-router)#redistribute static
Router1(config-router)#distribute-list 7 out static
Router1(config-router)#end
Router1#

Discussion

There are two main advantages to using default originate instead of simply redistributing static routes. The first is that you may have other static routes on your router that you do not want to distribute, or that you want to distribute with a different default metric. In this case, if you just use redistribute static, you will need to filter out the unwanted routes using route maps, as shown in Recipe 6.4, or a distribute-list, as we use in this recipe.

The other important advantage is that the default-information originate option lets you create a conditional ...