On Tue, 17 Feb 2026 20:13:02 +0100 Ondrej Zajicek <santiago@crfreenet.org> wrote:
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)
I've checked it now and it worked when forcing broadcast on Bird (I think I forgot to check broadcast before). So in short when Bird auto-defaulted to PtP and other router did broadcast I had Full/PtP state on Bird side and Full state on the Juniper (but no routes put into Bird routing table) But in reverse situation, when I forced Juniper to run PtP and forced Bird to run brodcast, the connection did not establish at all. So I'm confused why it even established in the first place
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).
Yeah I just kinda assumed the other devices did the logical thing here Cheers Mariusz -- Mariusz Gronczewski (XANi) <xani+bird@devrandom.pl> GnuPG: 0xEA8ACE64 https://devrandom.eu