Open Shortest Path First (OSPF)
42-29
42
•
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 a 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.
Command Usage
• There are no external routes in an OSPF stub area, so routes cannot be
redistributed from another protocol into a stub area. On the other hand, an
NSSA allows external routes from another protocol to be redistributed into its
own area, and then leaked to adjacent areas.
• This command can be used to simplify administration when connecting a
central site using OSPF to a remote site that is using a different routing
protocol. You can extend OSPF to cover the remote connection by defining
the area between the central router and the remote router as an NSSA.
• All routers in a NSSA must be configured with the same area ID.
• An NSSA is similar to a stub, because when the router is an ABR, it can
send a default route for other areas in the AS into the NSSA using the
default-
information-originate
keyword. However, an NSSA is different from a stub,
because when the router is an ASBR, it can import a default external AS route
(for routing protocol domains adjacent to the NSSA but not within the OSPF
AS) into the NSSA using the
default-information-originate
keyword.
• External routes advertised into an NSSA can include network destinations
outside the AS learned via OSPF, the default route, static routes, routes
imported from other routing protocols such as RIP, and networks directly
connected to the router that are not running OSPF.
• NSSA external LSAs (Type 7) are converted by any ABR adjacent to the NSSA
into external LSAs (Type-5), and propagated into other areas within the AS.
• Also, note that unlike stub areas, all Type-3 summary LSAs are always
imported into NSSAs to ensure that internal routes are always chosen over
Type-7 NSSA external routes.
• This router supports up to 16 total areas (either normal transit areas, stubs, or
NSSAs).
Example
This example creates a stub area 10.3.0.0, and assigns all interfaces with class B
addresses 10.3.x.x to the NSSA. It also instructs the router to generate external
LSAs into the NSSA when it is an NSSA ABR or NSSA ASBR.
Console(config-router)#area 10.3.0.0 nssa default-information-originate
Console(config-router)#network 10.3.0.0 255.255.0.0 area 10.2.0.0
Console(config-router)#
Summary of Contents for 8926EM
Page 6: ...ii ...
Page 34: ...Getting Started ...
Page 44: ...Introduction 1 10 1 ...
Page 62: ...Initial Configuration 2 18 2 ...
Page 64: ...Switch Management ...
Page 76: ...Configuring the Switch 3 12 3 ...
Page 118: ...Basic Management Tasks 4 42 4 ...
Page 164: ...User Authentication 6 28 6 ...
Page 176: ...Access Control Lists 7 12 7 ...
Page 284: ...Quality of Service 14 8 14 ...
Page 294: ...Multicast Filtering 15 10 15 ...
Page 300: ...Domain Name Service 16 6 16 ...
Page 310: ...Dynamic Host Configuration Protocol 17 10 17 ...
Page 320: ...Configuring Router Redundancy 18 10 18 ...
Page 344: ...IP Routing 19 24 19 ...
Page 356: ...Unicast Routing 20 12 20 Web Click Routing Protocol RIP Statistics Figure 20 5 RIP Statistics ...
Page 386: ...Unicast Routing 20 42 20 ...
Page 388: ...Command Line Interface ...
Page 400: ...Overview of the Command Line Interface 21 12 21 ...
Page 466: ...SNMP Commands 24 16 24 ...
Page 520: ...Access Control List Commands 26 18 26 ...
Page 546: ...Rate Limit Commands 30 2 30 ...
Page 612: ...VLAN Commands 34 24 34 ...
Page 626: ...Class of Service Commands 35 14 35 ...
Page 670: ...DHCP Commands 39 16 39 ...
Page 716: ...IP Interface Commands 41 36 41 ...
Page 768: ...IP Routing Commands 42 52 42 ...
Page 770: ...Appendices ...
Page 791: ......