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Configuring an NSSA area
A stub area cannot import external routes, but an NSSA area can import external routes into the OSPF
routing domain while retaining other stub area characteristics.
Do not configure the backbone area as an NSSA area or totally NSSA area.
To configure an NSSA area, configure the
nssa
command on all the routers attached to the area.
To configure a totally NSSA area, configure the
nssa
command on all the routers attached to the area
and configure the
nssa
no-summary
command on the ABR. The ABR of a totally NSSA area does not
advertise inter-area routes into the area.
To configure an NSSA area:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf
[
process-id
|
router-id
router-id
|
vpn-instance
vpn-instance-name
] *
N/A
3.
Enter area view.
area
area-id
N/A
4.
Configure the area as an
NSSA area.
nssa
[
default-route-advertise
[
cost
cost
|
nssa-only
|
route-policy
route-policy-name
|
type
type
] * |
no-import-route
|
no-summary
|
suppress-fa
|
[
translate-always
|
translate-never
] |
translator-stability-interval
value
]
*
By default, no area is configured as
an NSSA area.
5.
(Optional.) Specify a cost for
the default route advertised
to the NSSA area.
default-cost
cost
The default setting is 1.
This command takes effect only on
the ABR/ASBR of an NSSA or totally
NSSA area.
Configuring a virtual link
Virtual links are configured for connecting backbone area routers that have no direct physical links.
To configure a virtual link:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter OSPF view.
ospf
[
process-id
|
router-id
router-id
|
vpn-instance
vpn-instance-name
] *
N/A
3.
Enter area view.
area
area-id
N/A