advertise OSPF default route into a specific area?

[Maria Matejka]

Hello Lexi,

On Sat, Feb 22, 2025 at 01:34:51PM +0000, Lexi Winter wrote:

> i have an OSPF ABR in area 0 and area 1.  this router has a default
> route via a non-OSPF interface (kernel route, imported into BIRD using
> the 'kernel' protocol).  i'd like to advertise this route into area 1,
> but *not* into area 0.
> 
> how would i go about doing that?

I would filter out the default route on all the area 0 routers.

> please feel free to let me know if this is a bad idea or if i'm using
> OSPF wrong :-)

Well, OSPF isn't intended for filtering routes between areas this way.
Guessing from what you have written, it may make sense e.g. to run one
OSPF instance per area, assign each area a BGP private ASN and run BGP
between them.

Have a nice weekend! 
Maria

-- 
Maria Matejka (she/her) | BIRD Team Leader | CZ.NIC, z.s.p.o.
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