Black Box LGB6026A, Management Manual

Page: 1150 / 1289

– 1148 –
C
HAPTER
47 | IP Routing Commands
Open Shortest Path First (OSPFv2)
metric-value - Metric assigned to Type-7 default LSAs.
(Range: 1-16777214: Default: 1)
type-value
1 - Type 1 external route
2 - Type 2 external route (default) - Routers do not add internal
cost to the external route metric.
C
OMMAND
M
ODE
Router Configuration
D
EFAULT
S
ETTING
No NSSA is configured.
C
OMMAND
U
SAGE
◆
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).
E
XAMPLE
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)#