Importing (and then exporting) stubnet routes

[Ondrej Zajicek]

On Mon, Jun 21, 2021 at 12:49:38PM +0100, George Ross wrote:
> I'm sure I've seen something like this discussed recently, but I can't find 
> it in the mailing list archives, so apologies if I'm duplicating something.
> 
> Router A defines some OSPF stubnets.  Those are happily propagated to our 
> other OSPF routers.  What I can't get to work, though, is to import them 
> from OSPF into BIRD, so that I can then export them to BGP, even using 
> "all" as the import filter.
> 
> I can add them as direct routes and then export those, but that somehow
> doesn't feel right.  And on router B I can import them from OSPF and then
> export from there, but then we would end up with asymmetric paths which 
> would break connection-tracking.
> 
> Suggestions, pointers, explanations gratefully received!
> 
> Thanks.  2.0.8, in case it matters.

Hello

I think that this is missing behavior in BIRD, it would make sense that
both configured stubnets and configured aggregated area networks for ABRs
would be imported on local router (who defines them) as an OSPF
'unreachable' route, but BIRD does not do that.

In the absence of that, simple way is to just define such stubnets also
as static unreachable routes (to export to BGP and perhaps kernel).

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
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"To err is human -- to blame it on a computer is even more so."