2.15, ospf is broken

[Ondrej Zajicek]

On Tue, Mar 19, 2024 at 08:50:22AM +0400, Dmitry Melekhov wrote:
> Hello!
> 
> Just upgraded and got:
> ...
> Downgrade to 2.14 solved problem.
> 
> Is there fix for this or workaround?

Hello

There are two issues, both caused by commit
31aa62ae6d2e111e87c08b4b27a16ead968f0689:

1) BIRD could generate ECMP routes with multiple dev-only nexthops,
which Linux kernel accepts only in IPv4 but not in IPv6 case.

2) The commit breaks the way how next hops are inherited during next
hop calculations.

Both issues are restricted to physical PtP links (including L3
tunnels like GRE). The first issue is limited to ECMP IPv6 and can
be workarounded by disabling ECMP, the second one has wider impact.

Soha Jin sent patches for both of this issues [*], but i am leaning
towards making a quick bugfix release that reverts the original
commit, so we can take more time to evaluate the change.

[*] Patches:
https://bird.network.cz/pipermail/bird-users/2024-March/017475.html
https://bird.network.cz/pipermail/bird-users/2024-March/017504.html

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
"To err is human -- to blame it on a computer is even more so."