Indicates whether this ASBR router originates the default route
into the OSPF normal area(s). If set to 'only', the default route
is advertised into the OSPF normal area, provided the ASBR has
a route to 0.0.0.0/0 in its routing table. Alternatively, if set
to 'always', a default route is advertised into the OSPF domain
regardless of whether the ASBR has a route to 0.0.0.0/0. A value of
'none' has the effect of not originating the default route.