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. |