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Configuring the Open Shortest Path First Protocol (Version 2)
CLI R
EFERENCES
◆
"router ospf" on page 1751
"network area" on page 1768
◆
C
U
OMMAND
SAGE
Specify an Area ID and the corresponding network address range for
◆
each OSPF broadcast area. Each area identifies a logical group of OSPF
routers that actively exchange Link State Advertisements (LSAs) to
ensure that they share an identical view of the network topology.
Each area must be connected to a backbone area. This area passes
◆
routing information between other areas in the autonomous system. All
routers must be connected to the backbone, either directly, or through
a virtual link if a direct physical connection is not possible.
All areas are created as normal transit areas using the Network Area
◆
(Add) page. A normal area (or transit area) can send and receive
external LSAs. If necessary, an area can be configured as a not-so-
stubby area (NSSA) that can import external route information into its
area, or as a stubby area that cannot send or receive external LSAs.
An area must be assigned a range of subnetwork addresses. This area
◆
and the corresponding address range forms a routing interface, and can
be configured to aggregate LSAs from all of its subnetwork addresses
and exchange this information with other routers in the network as
described under
"Configuring Area Ranges (Route Summarization
for ABRs)" on page
◆
If an address range overlaps other network areas, 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.
P
ARAMETERS
These parameters are displayed:
Process ID – Protocol identifier used to distinguish between multiple
◆
routing instances. (Range: 1-65535)
IP Address – Address of the interfaces to add to the area.
◆
Netmask – Network mask of the address range to add to the area.
◆
◆
Area ID – Area to which the specified address or range is assigned. An
OSPF area identifies a group of routers that share common routing
information. The area ID can be in the form of an IPv4 address, or as a
four octet unsigned integer ranging from 0-4294967295.
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.
– 791 –
C
805.
| Unicast Routing
20
HAPTER
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