The default route is widely applied on the OSPF network to reduce routing entries in the routing table and filter specific routing information.
If the default route is imported to the OSPF routing domain and an OSPF router within it is configured with a static default route, you need to set the precedence of static default route lower than that of the imported default route. Otherwise, the default route may not be assigned the highest priority in the routing table.
ospf [ process-id ]
default-route-advertise [ [ always | permit-calculate-other ] | cost cost | type type | route-policy route-policy-name [ match-any ] ] *
When always is selected, you can import a default route to OSPF forcibly; otherwise, the routes can be imported only when local default routes exist.
To advertise Type-3 summary LSA of the specified default route, run the default-route-advertise summary cost cost command.
When summary is selected, you must first enable VPN; otherwise, the route cannot be aggregated.