Injecting Default routes

Injecting default route...
The purpose of injecting default route into an Eigrp process is to make the routers under the routing protocol to point to the router on which default route is configure.
There are different ways to do this.
1)Default-information originate:-
This command is used to inject the default route into the rip process, so as to make the routers to point towards the router on which command is set or we can say that this command enables router under the protocol (rip etc) to point towards the router on which default-information originate is set
2)Redistribution.
3)IP Summary-address.
Injecting default route using redistribution.

Scenario
3 routers A,B and C running Eigrp protocol and router A is an edge router pointing towards ISP and default route is configured on router A

Configuration.

RouterA>enable
RouterA#conf t
RouterA(config)#router eigrp 10
RouterA(config-router)#redistribute static
RouterA(config-router)#CTRL+Z
RouterA#



Configuration for Default information originate for same scenario

RouterA>enable
RouterA#conf t
RouterA(config)#router rip
RouterA(config-router)#version 2
RouterA(config-router)#default-information originate
RouterA(config-router)#CTRL+Z
RouterA#

Configuration for Summary Address



RouterA>enable
RouterA#conf t
RouterA(config)#int s0/1
RouterA(config-if)#ip summary-address eigrp 10 0.0.0.0 0.0.0.0
RouterA(config-if)#CTRL+Z
RouterA#