OSPF unexpectedly adds /128 interface route

[Lexi Winter]

Ondrej Zajicek wrote in <agG8FCXbKhBjqsvg at feanor>:
> On Sun, May 10, 2026 at 01:42:07PM +0100, Lexi Winter wrote:
> > i have an interface with a /64 address configured:
> >[...]
> > however, BIRD only adds a /128 route into the OSPF database
> 
> There are two reasons why it could generate /128 route instead of /64.
> Either BIRD thinks there is link down in the interface, or it is
> confused by its type and handles the interface as PtMP.

thanks.  setting 'check link no' fixed the problem, but i'm not sure
i understand why.

on the host, the interface is up:

	bridge0.500: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500

but BIRD considers it down (LinkDown):

	bridge0.500 up (index=28)
		MultiAccess Broadcast Multicast AdminUp LinkDown MTU=1500
		fe80::1/64 (Preferred, scope link)
		fd13:480d:2ffa:3::1/64 (Preferred, scope site)

looking at another interface that BIRD considers LinkUp:

	bridge0 up (index=27)
		MultiAccess Broadcast Multicast AdminUp LinkUp MTU=9000

i see it has the LOWER_UP flag in ifconfig:

	bridge0: flags=1008843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,LOWER_UP> metric 0 mtu 9000

so, it seems like the problem is that the host system isn't setting this
flag on the vlan interface, even though it probably should be set since
the underlying interface is up.

does that seem like a reasonable explanation for this behaviour?  if so,
i will go away and see if we can fix the host :-)
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 228 bytes
Desc: not available
URL: <http://trubka.network.cz/pipermail/bird-users/attachments/20260511/07fa6425/attachment.sig>