IPv6 prefix is not stored to kernel when multipath is enabled in 1.6.8

[Jimmy Lim]

Hi Maria,

It looks like it doesn't like the configuration of directing IPv6 prefix
that we receive from gw (we have 3 sessions) to ifname. The multipath is
working fine for IPv6 after I removed that configuration, and it works for
both bird v1 and v2:

fdaa::/16 proto bird src fdaa:dc60:20:1::a3e:a00b metric 1024
> nexthop via fdaa:dc00:20::644d:3b01 dev wg1 weight 1
> nexthop via fdaa:dc00:20::644d:3c01 dev wg2 weight 1
> nexthop via fdaa:dc00:20:a000::101 dev wg3 weight 1


Thanks guys for taking a look into my case.

Cheers,
Jimmy

On Tue, Feb 18, 2025 at 2:46 PM Maria Matejka <maria.matejka at nic.cz> wrote:

> Hello Jimmy,
>
> what is your kernel version? (notable critical points are 4.11 and 5.10)
> How do the routes look like? (they may just be unmergeable)
>
> Maria
>
>
> On 18 February 2025 04:28:19 CET, Jimmy Lim <jhalim10 at gmail.com> wrote:
>
>> Hi Maria,
>>
>> Thanks for your update. I have just run the test in another box
>> running BIRD 2.0.12. I encountered the same issue. The IPv6 prefix is not
>> installed in the kernel if there is more than 1 equal path available. This
>> is what I see in the log:
>>
>>> Feb 17 19:01:05 n002-002 bird[174542]: kernel2: fdaa::/16: installing
>>> Feb 17 19:02:05 n002-002 bird[174542]: kernel2: fdaa::/16: installing
>>> Feb 17 19:03:05 n002-002 bird[174542]: kernel2: fdaa::/16: installing
>>> Feb 17 19:04:05 n002-002 bird[174542]: kernel2: fdaa::/16: installing
>>> Feb 17 19:05:05 n002-002 bird[174542]: kernel2: fdaa::/16: installing
>>> Feb 17 19:06:05 n002-002 bird[174542]: kernel2: fdaa::/16: installing
>>> Feb 17 19:07:05 n002-002 bird[174542]: kernel2: fdaa::/16: installing
>>> Feb 17 19:08:05 n002-002 bird[174542]: kernel2: fdaa::/16: installing
>>> Feb 17 19:09:05 n002-002 bird[174542]: kernel2: fdaa::/16: installing
>>
>>
>> Do you have the sample working configuration for multipath? Basically I
>> have just configured inside protocol kernel. Thanks.
>>
>>> merge paths on;
>>
>>
>> Thanks,
>> Jimmy
>>
>> On Fri, Feb 14, 2025 at 6:40 PM Maria Matejka <maria.matejka at nic.cz>
>> wrote:
>>
>>> On Fri, Feb 14, 2025 at 05:52:18PM +0800, Jimmy Lim wrote:
>>>
>>> I thought the issue might be related to configuration instead of bird
>>> version 😕
>>>
>>> There is quite some code difference between BIRD 1 and 2, and I do
>>> remember that the IPv6 multipath implementation was unstable for some time
>>> in the Netlink API.
>>>
>>> And that is the reason why we stopped supporting BIRD 1. We ourselves
>>> can’t keep track about everything here and there, and even though Santiago
>>> has superhuman powers and remembers which part worked how even in 1.3.0 …
>>> no, please. We actually do not know how much we have fixed in BIRD 2 and
>>> ignored in BIRD 1. There is a lot of development passed by.
>>>
>>> Let me try to use another box that run bird 2 for testing as well.
>>>
>>> Seriously. Do. Upgrade. Now. We announced the EOL for a reason. Tell
>>> your manager that BIRD 1 is EOL. It is not OK to run it in production now.
>>> You won’t even get packages for new distros for BIRD 1.
>>>
>>> Thank you for your understanding
>>> Maria
>>>
>>> –
>>> Maria Matejka (she/her) | BIRD Team Leader | CZ.NIC, z.s.p.o.
>>>
>> --
> Maria Matejka (she/her) | BIRD Team Leader | CZ.NIC, z.s.p.o.
>
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