Configuring OSPF (Open Shortest Path First) protocol to provide routing information between the routers is simple process. OSPF is link state protocol which provides partial update to routers instead of sending the entire routing table from one router to another. It uses cost based metric with administrative distance of 110. It sends the entire routing table when you configure first time and periodically sends the new updates only. It provides loop free topology, fast convergence, and supports classless routing (CIDR).
Unlike, RIPv2, when you configuring OSPF, you need to specify process ID, wildcard mask and area. Process ID is local router ID and does not have any significant meaning to the other routers. Wildcard mask is reversed subnet mask of the network, for example if the subnet mask is 255.255.255.0, the wild-card will be 0.0.0.255. Area is way of administratively grouping routers together.
To configure the OSPF route:
1. On the router privilege mode type conf t to enter the configuration mode.
2. Type router ospf process-id – process-id can be any number and 2 routers on the same network can have same or different process IDs. Example; router ospf 1
3. Type network ip wild-card mask area area-id, for example if your other routers IP address is class C with the ip 192.168.10.2 and you want identify area as 0 than type network 192.168.10.2 0.0.0.255 area 10 or net 192.168.10.2 0.0.0.255 area 0.
4. Type end
Note: area 0 is the OSPF backbone area and mutiple areas connect back to area 0.