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...
Enter system view
Enter OSPF view
Enter area view
Configure the area as an NSSA
area
Specify a cost for the default
route advertised to the NSSA
area
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...
Enter system view
Use the command...
system-view
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
area area-id
nssa [ default-route-advertise |
no-import-route | no-summary |
translate-always |
translator-stability-interval value ]
*
default-cost cost
Use the command...
system-view
76
Remarks
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—
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Required
Not configured by default.
Optional
1 by default.
Remarks
—