What is an OSPF area?

OSPF can divide a large routing domain into areas. The backbone is Area 0. Other normal areas should connect to the backbone.

  • Internal Router — all OSPF interfaces belong to one area.
  • ABR — connects multiple areas and keeps their link-state databases separated.
  • ASBR — injects routes from another routing domain into OSPF.

Configuration example

router ospf 1
 router-id 1.1.1.1
 network 10.0.0.0 0.0.0.255 area 0
 network 10.1.0.0 0.0.255.255 area 10

Match network statements and area design to the actual topology and subnets. Verify with show ip ospf interface brief, show ip ospf neighbor and show ip route ospf.