Reducing AS-external-LSAs and inter-area-prefix-LSAs

An OSPFv3 ASBR uses AS-external-LSAs to originate advertisements of a route to another routing domain. These advertisements are:

• Flooded in the area in which the ASBR operates.

• Injected into the backbone area and then propagated to any other OSPFv3 areas (except stub and NSSA areas) within the local OSPFv3 AS. If the AS includes an NSSA, there are two additional options:

  • If the NSSA includes an ASBR, you can suppress advertising some or all of its summarized external routes into the backbone area.

  • Replace all inter-area-prefix-LSAs and all external routes from the backbone area with the default route (::/0).