OSPF loopback

tonydotigr

Does each OSPF area need to be configured with a loopback interface?

EdTheLad

tonydotigr wrote:

Does each OSPF area need to be configured with a loopback interface?

Nope!
Each router in an ospf network needs a router id in order to identify its LSAS.
The system can assign this router id automatically or you can configure it yourself.If automatically assigned the router will pick the highest ip address from configured loopback interfaces or if no loopback interfaces are configured it will choose the highest ip address from a physical interface.
It is good practice to configure the router id as a loopback address for stability in your network.If you create virtual links in your network these are referenced with the router id, if you experience a router problem and the router reboots and chooses a different router id all your virtual links are now invalid.So best practice is to create a loopback interface and assign it as your
router id.