Bird OSPF bug? (Mutliple areas, rfc1583compat off, cost ignored)

[Ondrej Zajicek]

On Sat, Jan 26, 2019 at 02:07:52PM +0700, Igor Podlesny wrote:
> I have test lab -- two OSPF routers, Bird 1.6.4: A, B.
> 
> 2 areas defined: 0.0.0.0, 0.0.0.1. Export "all".
> 
> When rfc1583compat is Off I observe default route gets propagated via
> area 0.0.0.1 in despite its interfaces have higher costs than area
> 0.0.0.0's have.
> 
> Turning rfc1583compat On changes it to expected behaviour: interfaces
> costs are respected again.
> 
> Bug or am I missing some piece of OSPF knowledge here?

Hi

I think it is correct. In OSPF, intra-area paths using non-backbone areas
are preferred over shorter backbone or inter-area paths. See RFC 2328,
section 16.4.1.

Option rfc1583compat disables this behavior and changes it to simpler,
older RFC 1583 behavior, but that behavior may lead to routing loops in
some border cases.

-- 
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."