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Configuring OSPFv3 OSPFv3 Overview
OmniSwitch 6800/6850/9000 Advanced Routing Configuration Guide December 2007 page 2-11
Stub Areas
OSPFv3 allows certain areas to be configured as stub areas. A stub area is an area with routers that have
no AS external Link State Advertisements (LSAs).
In order to take advantage of the OSPFv3 stub area support, default routing must be used in the stub area.
This is accomplished by configuring one or more of the stub area’s border routers to advertise a default
route into the stub area. The default routes will match any destination that is not explicitly reachable by an
intra-area or inter-area path (i.e., AS external destinations).
OSPFv3 Stub Area
Area 1 and Area 3 could be configured as stub areas. Stub areas are configured using the OSPFv3 ipv6 ospf
area command, described in “Creating an Area” on page 2-15. For more overview information on areas, see
“OSPFv3 Areas” on page 2-9.
The OSPFv3 protocol ensures that all routers belonging to an area agree on whether the area has been
configured as a stub. This guarantees that no confusion will arise in the flooding of AS external advertise-
ments.
Two restrictions on the use of stub areas are:
• Virtual links cannot be configured through stub areas.
• AS boundary routers cannot be placed internal to stub areas.
Virtual Link
Area 3
(stub)
Area 2
Area 1
(stub)
Backbone
Backbone