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NOTE:
•
You must use the
stub
command on routers attached to a stub area.
•
Using the
default-cost
command only takes effect on the ABR of a stub area.
•
The backbone area cannot be a totally stub area.
•
A (totally) stub area cannot have an ASBR because AS external routes cannot be distributed into the stub
area.
•
Virtual links cannot transit totally stub areas.
Configuring an NSSA area
A stub area cannot redistribute routes. Configure the area as an NSSA area to allow for route
redistribution by keeping other stub area characteristics.
Follow these steps to configure an NSSA area:
To do…
Use the command…
Remarks
Enter system view
system-view
—
Enter OSPF view
ospf
[
process-id
|
router-id
router-id
|
vpn-instance
vpn-instance-name
] *
—
Enter area view
area
area-id
—
Configure the area as an NSSA
area
nssa
[
default-route-advertise
|
no-import-route
|
no-summary
|
translate-always
|
translator-stability-interval
value
]
*
Required
Not configured by default.
Specify a cost for the default
route advertised to the NSSA
area
default-cost
cost
Optional
1 by default.
NOTE:
•
You must use the
nssa
command on all the routers attached to an NSSA area.
•
The
default-cost
command is available only on the ABR/ASBR of an NSSA area.
Configuring a virtual link
Non-backbone areas exchange routing information via the backbone area. Connectivity between the
backbone and non-backbone areas and within the backbone must be maintained.
If the required physical links are not available for this connectivity maintenance, you can configure virtual
links to resolve it.
Follow these steps to configure a virtual link:
To do…
Use the command…
Remarks
Enter system view
system-view
—