Configuring OSPFv3 NSSAs

Derived from a stub area, an NSSA allows AS external routes to be imported; an ASBR advertises Type 7 NSSA LSAs in the local NSSA.

Context

NSSAs are introduced because stub areas cannot import external routes. An NSSA allows the transmission of Type 7 LSAs, which are generated by ASBRs in an NSSA. When reaching the ABR that is responsible for converting Type 7 LSAs into Type 5 LSAs in the NSSA, Type 7 LSAs with the P-bit being set and the forwarding address being a non-zero address are converted to AS-external LSAs and advertised to other areas.

Procedure

Access the system view.
system-view
Access the OSPFv3 process view.
ospfv3 [ process-id ]
(Optical) Run:
```
lsa-forwarding-address { standard | zero-translate }
```
The OSPFv3 forwarding address (FA) function is enabled.
Access the OSPFv3 area view.
area area-id
Configure the area as an NSSA.
nssa [ default-route-advertise [ cost cost | type type | tag tag ] ^* | no-import-route | no-summary | translator-always | translator-interval translator-interval | set-n-bit ] ^*

To connect routers to an NSSA, you need to run the nssa command to configure NSSA attributes for the area to which the routers belong.

The area may be updated after NSSA attributes are configured or deleted. Thus, the NSSA attributes can be re-configured or deleted only after the last update of NSSA attributes is complete.