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IP Routing Commands
4-275
4
Command Usage
• All routers in a stub must be configured with the same area ID.
• Routing table space is saved in a stub by blocking Type-4 AS summary LSAs
and Type 5 external LSAs. The default setting for this command completely
isolates the stub by blocking Type-3 summary LSAs that advertise the default
route for destinations external to the local area or the autonomous system.
•Use the area default-cost command to specify the cost of a default summary
route sent into a stub by an ABR.
• This router supports up to 16 total areas (either normal transit areas, stubs, or
NSSAs).
Example
This example creates a stub area 10.2.0.0, and assigns all interfaces with class B
addresses 10.2.x.x to the stub.
Related Commands
area default-cost (4-271)
area nssa
This command defines a not-so-stubby area (NSSA). To remove an NSSA, use the
no form without any optional keywords. To remove an optional attribute, use the no
form without the relevant keyword.
Syntax
[no] area area-id nssa [no-redistribution] [default-information-originate]
• area-id - Identifies the NSSA.
(The area ID must be in the form of an IP address.)
• no-redistribution - Use this keyword when the router is an NSSA Area
Border Router (ABR) and you want the redistribute command to import
routes only into normal areas, and not into the NSSA. In other words, this
keyword prevents the NSSA ABR from advertising external routing
information (learned via routers in other areas) into the NSSA.
• default-information-originate - When the router is an NSSA Area Border
Router (ABR) or an NSSA Autonomous System Boundary Router (ASBR),
this parameter causes it to generate Type-7 default LSA into the NSSA.
This default provides a route to other areas within the AS for an NSSA ABR,
or to areas outside the AS for an NSSA ASBR.
Command Mode
Router Configuration
Default Setting
No NSSA is configured.
Console(config-router)#area 10.2.0.0 stub
Console(config-router)#network 10.2.0.0 0.255.255.255 area 10.2.0.0
Console(config-router)#