Configuration planning is essential to organize routers, backbone, non-backbone, stub, NSSA areas, and transit links. OSPF provides essential defaults for basic protocol operability. You can configure or modify commands and parameters. OSPF is not enabled by default.
The minimal OSPF parameters which should be configured to deploy OSPF are described below.
Router ID
Each router running OSPF must be configured with a unique router ID. The router ID is used by both OSPF and BGP routing protocols in the routing table manager.
When configuring a new router ID, protocols are not automatically restarted with the new router ID. Shut down and restart the protocol to initialize the new router ID.
OSPF instance
OSPF instances must be defined when configuring multiple instances and the instance being configured is not the base instance.
An area
At least one OSPF area must be created. An interface must be assigned to each OSPF area.
Interfaces
An interface is the connection between a router and one of its attached networks. An interface has state information associated with it, which is obtained from the underlying lower level protocols and the routing protocol itself. An interface to a network has associated with it a single IP address and mask (unless the network is an unnumbered point-to-point network). An interface is sometimes also referred to as a link.