On Tue, Feb 17, 2026 at 07:16:03PM +0100, Mariusz Gronczewski wrote:
> > Hi
> >
> > Isn't that just mismatched ptp/broadcast mode? BIRD defaults to ptp
> > mode for /30 and similar networks, but i thought that in mismatch
> > mode it would not even make an adjacency. But perhaps it makes
> > adjacency, just not work correctly.
> >
> > Try setting explicitly broadcast mode (or ptp mode on the other side).
> >
>
> First, thanks for help, I didn't thought about trying to change stuff
> on the router/switch side ("it was working fine before") and forcing
> Juniper/Brocade side to PtP was enough.
>
> I tried every option on Bird side, didn't help, setting
> it to p2p on the router/switch side worked, but I'm more confused than
> before because:
Setting 'type broadcast' for the interface on BIRD side (when
router/switch side was not set to ptp) with /30 did not work?
(i am not sure about /31)
You can also use 'show ospf interface' to see which mode (type) is used
on the interface.
> * the other devices talked between them just fine (in similar /31 vlans
> without PtP being explicitly set)
> * the same setup in FRR worked just fine (not needing to set PtP there
> too)
> * the same setup with 2 Bird instances (albeit thru wireguard tunnels)
> also works fine (PtP mode is enabled automatically)
I think other devices always defaults to broadcast mode on ethernet,
while BIRD defaults to ptp mode when an opposite address is known (i.e.
/30, /31, /32 with peer address).
--
Elen sila lumenn' omentielvo
Ondrej 'Santiago' Zajicek (email: [email protected])
"To err is human -- to blame it on a computer is even more so."
