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Command Usage
• An area ID uniquely defines an OSPF broadcast area. The area ID 0.0.0.0
indicates the OSPF backbone for an autonomous system. Each router (which
is not already part of the backbone) must be connected to the backbone via a
direct connection or a virtual link.
• Set the area ID to the same value for all routers on a network segment using
the network mask to add one or more interfaces to an area.
• Be sure to include the primary address for an interface in the network area,
otherwise, OSPF will not operate for any secondary addresses covered by the
command.
• An interface can only be assigned to a single area. If an address range is
overlapped in subsequent network area commands, the router will implement
the address range for the area specified in the last command, and ignore the
overlapping ranges in subsequent commands. However, note that if a more
specific address range is removed from an area, the interface belonging to
that range may still remain active if a less specific address range covering that
area has been specified.
• If an address range is overlapped in subsequent network area commands, the
router will use the network area with the address range that most closely
matches the interface address. Also, note that if a more specific address
range is removed from an area, the interface belonging to that range may still
remain active if a less specific address range covering that area has been
specified.
• This router supports up to 64 OSPF router interfaces, and up to 16 total areas
(either normal transit areas, stubs, or NSSAs).
Example
This example creates the backbone 0.0.0.0 covering class B addresses 10.1.x.x,
and a normal transit area 10.2.9.0 covering the class C addresses 10.2.9.x.
Console(config-router)#network 10.1.0.0 255.255.0.0 area 0.0.0.0
Console(config-router)#network 10.2.9.0 255.255.255.0 area 10.1.0.0
Console(config-router)#
area stub
This command defines a stub area. To remove a stub, use the no form without the
optional keyword. To alter the summary attribute, use the no form with the summary
or no-summary keyword.
Syntax
[no] area area-id stub [summary | no-summary]
• area-id - Identifies the stub area.
(The area ID must be in the form of an IPv4 address.)
• summary - Makes an Area Border Router (ABR) send a summary link
advertisement into the stub area.
• no-summary - Stops an Area Border Router (ABR) from sending a
summary link advertisement into the stub area.
Open Shortest Path First (OSPF)
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