Configuring OSPF

Cisco OSPF Router Commands:

-(config)#router ospf 1 (1 is a process ID between 1 – 65535.  It is locally significant)

-(config-router)#network 192.168.0.0 0.0.255.255 area 0 (This will add any interface with a 192.168.x.x IP address to Area 0)

-#show ip ospf neighbor

-(config-router)#network 192.168.1.1 0.0.0.0 area 0 (This will add the “network” associated with the 192.168.1.1 interface to Area 0)

-R1(config-router)#default-information originate (This command will propagate any default information on R1 (i.e. def. route) via OSPF)

Creating an ABR (Area Border Router)

–R3(config-router)#network 172.30.0.0 0.0.7.255 area 1 (This simple additional command makes R3 an ABR; this router will now be routing between two different Areas i.e. routes within Area 0 and the 172.30.0.0 networks in Area 1)

-R3#show ip protocols (will show the networks this router is routing for)

Since the whole point of creating different/separate Areas is to summarize routes between the areas the following command summarizes the routes:

-R3(config-router)#area 1 range 172.30.0.0 255.255.248.0 (This command will create a summary route for the172.30.x.x networks on R3 associated with Area 1)

Note: Now the Area 1 routes will be displayed as “IA” (Inter-Area) routes within the neighboring router’s routing tables