Route Redistribution Between OSPF and EIGRP

As discussed in the previous post, Router Redistribution is a technique that allows you to redistribute routes learned by one routing protocol or algorithm into another routing protocol or algorithm. We have also explained the detailed steps how to redistribute RIP routes into EIGRP. In this article, we are going to explain how to perform route redistribution between OSPF and EIGRP routing protocols. We would recommend you to visit the following articles before proceed to next.

We are going to use the following topology to demonstrate how to redistribute EIGRP routes into OSPF and OSPF routes into EIGRP. Use your favorite simulator (Cisco Packet Tracer or GNS3) to create the following topology and configure the appropriate IP addresses.Route Redistribution between OSPF and EIGRP

Perform OSPF and EIGRP Routings

Once you have configured the appropriate IP address on all the routers, the next step is to prepare your topology to perform route redistribution. For this, following steps are needed:

  1. First of all, configure EIGRP routing on Router1.
Router1(config)#router eigrp 100
Router1(config-router)#network 10.0.0.0
Router1(config-router)#network 192.168.0.0
Router1(config-router)#exit
  1. Next, move on to Router2 and configure EIGRP routing.
Router2(config)#router eigrp 100
Router2(config-router)#network 192.168.0.0
Router2(config-router)#exit
  1. On the same router (Router2), you also need to configure OSPF routing. We assume that our OSPF routers (Router1 and Router2) belong to area 0.
Router2(config)#router ospf 100
Router2(config-router)#network 192.168.1.0 0.0.0.255 area 0
Router2(config-router)#exit
  • The following figure shows the routing configuration of Router2.OSPF and EIGRP Redistribution
  1. Next, move on to Router3 and configure OSPF routing.
Router3(config)#router ospf 100
Router3(config-router)#network 192.168.1.0 0.0.0.255 area 0
Router3(config-router)#network 20.0.0.0 0.255.255.255 area 0
Router3(config-router)#exit
  1. Next, move on to Router1 and execute the following command to examine the routing table.
Router1#show ip route

Route Redistribution on Cisco Router

  1. In the preceding figure, you can see that Router1 has only the directly connected networks. The routes of Router3 cannot be added (advertized) until you perform the route redistribution.

Perform Route Redistribution Between OSPF and EIGRP

Now, you have prepared your network topology. Let’s see how to redistribute EIGRP routes into OSPF.

  1. To redistribute EIGRP routes into OSPF, you need to execute the following commands on Router2.
    Router2(config)#router eigrp 100 
    Router2(config-router)#redistribute ospf 100 metric 1000 100 255 1 1500
  2. The following figure shows how to redistribute EIGRP routes into OSPF. Redistribute EIGRP routes into OSPF on Cisco RouterNote: Take a close look up at the preceding figure to understand the syntax and values used to inject EIGRP routes into OSPF.
  3. Now, let’s see how to redistribute OSPF routes into EIGRP. To do so, execute the following commands on Router2.
    Router2(config)#router ospf 100 
    Router2(config-router)#redistribute eigrp 100 metric 1 subnets
  4. The following figure shows how to redistribute OSPF routes into EIGRP.Injecting ospf routes into eigrp
  5. Once you have performed route redistribution between OSPF and EIGRP, move on to Router1 and view the routing table.
    Router1#show ip route

    Injecting routes between ospf and eigrp

  6. What changes you have noticed?. In the above-mentioned figure, you can see that 20.0.0.0/8 and 192.168.1.0/24 networks are added through the External EIGRP routing algorithm. Now, view the routing table on Router3.
Router3#show ip route

External OSPF Routing Protocl

In the preceding figure, you can see that 10.0.0.0/8 and 192.168.0.0/24 networks are added through the external OSPF protocol. Now, Router1 and Router3 can communicate to each other.

Hope, it helped you. If you get stuck anywhere during the process of route redistribution between OSPF and EIGRP. Please drop your queries in the comment box. It would be highly appreciable if you like and share this article.

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