IPv4 route via IPv6 next hop: Netlink: Network unreachable

[Anton Danilov]

Hello.
Check output of 'ip route get 2a0a:e5c0:1:9::2` first.

On Wed, 1 Apr 2020 at 16:00, Nico Schottelius
<nico.schottelius at ungleich.ch> wrote:
>
>
> Hello,
>
> I'm running 2.0.7 on Linux 5.4.18-0-lts (Alpine)
> and I receive the route 193.228.143.0/24 from
> 2a0a:e5c0:1:9::2. However it is never set into the kernel, with the
> error message "Netlink: Network unreachable" in syslog.
>
> Has anyone seen this problem recently? I'm not sure if this is really a
> bird2 problem or not, to be honest:
>
> The kernel reports many messages like this in dmesg:
> [4541983.369058] netlink: 'bird': attribute type 5 has an invalid length.
>
> However, I am also puzzled that manually adding the route seems to fail:
>
> [14:44] router1.place6:/var/log# ip route add 193.228.143.0/24 via inet6 2a0a:e5c0:1:9::2
> RTNETLINK answers: Invalid argument
> [14:45] router1.place6:/var/log# ip route add 193.228.143.0/24 nexthop via inet6 2a0a:e5c0:1:9::2
> RTNETLINK answers: Invalid argument
> [14:45] router1.place6:/var/log# ip route add 193.228.143.0/24 nexthop via inet6 2a0a:e5c0:1:9::2 dev bond0.25
> RTNETLINK answers: Invalid argument
> [14:45] router1.place6:/var/log#
>
> bird status:
>
> bird> show route all protocol bluecmd_v6
> Table master4:
> 193.228.143.0/24     unicast [bluecmd_v6 14:31:15.880] ! (100) [AS206858i]
>         via 2a0a:e5c0:1:9::2 on bond0.25
>         Type: BGP univ
>         BGP.origin: IGP
>         BGP.as_path: 206858
>         BGP.next_hop: 2a0a:e5c0:1:9::2
>         BGP.local_pref: 100
>
> Table master6:
> 2a10:11c0:114::/48   unicast [bluecmd_v6 14:31:15.880] * (100) [AS206858?]
>         via 2a0a:e5c0:1:9::2 on bond0.25
>         Type: BGP univ
>         BGP.origin: Incomplete
>         BGP.as_path: 206858
>         BGP.next_hop: 2a0a:e5c0:1:9::2 fe80::21c:73ff:fe2c:6eca
>         BGP.local_pref: 100
> bird>
>
> bird2 config:
>
> protocol bgp bluecmd_v6 {
>         local as 209898;
>         neighbor 2a0a:e5c0:1:9::2 as 206858;
>         direct;
>
>         ipv4 {
>             extended next hop;
>
>             import filter from_inside_customer;
>             export filter only_default_route;
>         };
>
>         ipv6 {
>             import filter from_inside_customer;
>             export filter only_default_route;
>         };
>
>         default bgp_local_pref pref_normal;
> }
>
> syslog:
>
> Apr  1 14:31:15 router1 daemon.warn bird: Netlink: Network unreachable
> Apr  1 14:31:22 router1 daemon.warn bird: Netlink: Network unreachable
> Apr  1 14:31:42 router1 daemon.warn bird: Netlink: Network unreachable
> ...
>
>
> Bird / Kernel / etc.:
>
> [14:33] router1.place6:/var/log# bird --version
> BIRD version 2.0.7
> [14:35] router1.place6:/var/log# uname -a
> Linux router1 5.4.18-0-lts #1-Alpine SMP Thu, 06 Feb 2020 09:27:36 UTC x86_64 GNU/Linux
> [14:36] router1.place6:/var/log#
>
> For reference is also attached the configuration of the opposite side
> (Arista 7050):
>
> router bgp 206858
>    vrf PUBLIC
>       router-id 193.228.143.0
>       neighbor 2a0a:e5c0:1:9::5 remote-as 209898
>       neighbor 2a0a:e5c0:1:9::5 next-hop-self
>       neighbor 2a0a:e5c0:1:9::5 maximum-routes 0
>       !
>       address-family ipv4
>          bgp next-hop address-family ipv6
>          neighbor 2a0a:e5c0:1:9::5 activate
>          neighbor 2a0a:e5c0:1:9::5 next-hop address-family ipv6 originate
>          network 193.228.143.0/24
>       !
>       address-family ipv6
>          neighbor 2a0a:e5c0:1:9::5 activate
>          network 2a10:11c0:114::/48
>
> linthal-core(vrf:PUBLIC)(config-router-bgp-vrf-PUBLIC)#show ipv6 bgp neighbors 2a0a:e5c0:1:9::5 advertised-routes detail
>
> BGP routing table information for VRF PUBLIC
> Router identifier 193.228.143.0, local AS number 206858
> Update wait-install is disabled
> BGP routing table entry for 2a10:11c0:114::/48
>  Paths: 1 available
>   206858
>     2a0a:e5c0:1:9::2 from - (193.228.143.0)
>       Origin INCOMPLETE, metric -, localpref -, weight -, valid, local, best
>       Rx SAFI: Unicast
> BGP routing table entry for 193.228.143.0/24
>  Paths: 1 available
>   206858
>     - from - (193.228.143.0)
>       Origin IGP, metric -, localpref -, weight -, valid, local, best
>       Rx SAFI: Unicast
>
>
> Any pointer in the right direction would be appreciated!
>
> Cheers,
>
> Nico
>
>
> --
> Modern, affordable, Swiss Virtual Machines. Visit www.datacenterlight.ch



-- 
Anton Danilov.