Hello Daniel,

this looks fishy. I tried a trivial config like this on my laptop as follows and it works. Could you please disclose the full table? There are some details in the recursive nexthop resolution algorithm (preventing infinite resolution loops) which may apply to your case. BTW, is there really no message in the log?

The config:

protocol device {}
protocol kernel {
  ipv6 { import all; export none; };
  learn;
}

protocol static {
  ipv6;
  route fdca:db8::/32 recursive ::;
}

The table:

Table master6:
::/0                 unicast [kernel1 21:42:38.893] * (10)
    via fe80::feed:dee4:fe00:23d3 on wlo1
    Type: inherit univ
    Kernel.source: 9
    Kernel.metric: 600
2a00:1028:dead:beef::/64 unicast [kernel1 21:42:38.893] * (10)
    dev wlo1
    Type: inherit univ
    Kernel.source: 9
    Kernel.metric: 600
fdca:db8::/32        unicast [static1 21:42:38.891] * (200)
    via fe80::feed:dee4:fe00:23d3 on wlo1
    Type: static univ

Have a nice evening or any other part of the day!
Maria

Hi Alexander,

On Tue, Jun 27, 2023 at 04:48:46PM +0200, Alexander Zubkov wrote:

Not sure, but I would guess it can be related to the local address. It
might try to pick the first interface with such network.

Could you try your setup with some route that has the nexthop from a
unique subnet configured on the interface? At least to check if it will
become reachable or not.

Ok, if I add a route like `2000::/64 dev enp1s0 via
fe80::fc00:3ff:fec7:cd05` to the kernel and recurse through that it does
work.

    protocol static static_export_kernel2 {
        ipv6;
        igp table master6;
        route 2001:db8::/64 recursive 2000::1234;
    }

    $ ip -6 route add 2000::/64 dev enp1s0 via fe80::fc00:3ff:fec7:cd05
    $ birdc show route protocol static_export_kernel2 all
    2001:db8::/64        unicast [static_export_kernel2 16:01:20.131] * (200)
            via fe80::fc00:3ff:fec7:cd05 on enp1s0
            Type: static univ

Or it might be that routes imported from the kernel are marked as
recursive, so it does not resolve because Bird does not allow double
recursion.

If I remove the 2000::/64 route the recursive route goes back to
unreachable. So something seems to be preventing recursion through the
default route specifically, but it evidently doesn't have anything to do
with the route coming from the kernel.

    $ ip -6 route del 2000::/64 dev enp1s0 via fe80::fc00:3ff:fec7:cd05
    $ birdc show route protocol static_export_kernel2 all
    2001:db8::/64        unreachable [static_export_kernel2 16:01:20.131] * (200)
            Type: static univ

Weird.

Thanks for your suggestions,
--Daniel

-- 
Maria Matejka (she/her) | BIRD Team Leader | CZ.NIC, z.s.p.o.