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OSPF Overview 449
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OSPF interfaces — An OSPF interface is an IP interface that you
configure to send and receive OSPF traffic. When you configure an
OSPF interface, you define the behavior and role of the interface
within the OSPF routing domain. For example, router priority
determines designated router selection, cost determines the expense
associated with using the interface, and the Hello interval directly
affects how fast topological changes are detected. For more
information, see “OSPF Interfaces” later in this chapter.
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Link state databases — OSPF routers advertise routes using link
state advertisements. The link state database contains the link state
advertisements from throughout the area to which an OSPF interface
is attached. For more information, see “Link State Databases” later in
this chapter.
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Neighbors — OSPF interfaces attached to a common network are
called neighbors; adjacent neighbors exchange link state database
information. On broadcast networks, neighbors are discovered
dynamically using the Hello protocol. On nonbroadcast multiaccess
networks, you must statically configure neighbors. Your system allows
you to display all neighbors in the locality of the router, as well
configure them when needed. For more information, see “Neighbors”
later in this chapter.
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Router IDs — A router ID identifies the router to other routers within
the autonomous system. In addition, it serves as a tie-breaker in the
designated router election. You systems gives you three methods by
which you can configure a router ID for an OSPF interface. For more
information, see “Router IDs” later in this chapter.
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OSPF memory partition — You can display how much memory your
system allocates for OSPF data processing and adjust this memory
allocation if needed. For more information, see “OSPF Memory
Partition” later in this chapter.
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Stub default metrics — External link state advertisements are not
propagated into stub areas. Instead, the area border router for a stub
area injects a single external default route into the area. Your system
allows you to configure an area border router to advertise a single
external default route into the stub area while specifying the cost of
the default route. For more information, see “Stub Default Metrics”
later in this chapter.