On Tue, Jul 28, 2026, 10:34 a.m. Ales Musil <[email protected]> wrote:

>
>
> On Tue, Jun 30, 2026 at 1:42 PM Dumitru Ceara <[email protected]> wrote:
>
>> Hi Ales,
>>
>> On 6/26/26 3:02 PM, Ales Musil wrote:
>> > On Fri, Jun 26, 2026 at 2:09 PM Dumitru Ceara via dev <
>> > [email protected]> wrote:
>> >
>> >> The flows in ls_in_l2_lkup, generated by
>> >> build_lswitch_rport_arp_req_flow(), matched ARP requests and
>> >> ND_NS for router-owned IPs without restricting eth.dst to
>> >> broadcast/multicast.  This caused unicast ARP requests
>> >> (eth.dst == router_MAC) to be intercepted and flooded into the
>> >> L2 domain.
>> >>
>> >> On switches with 200+ ports this flooding can exceed the OVS
>> >> 4096 resubmit limit, dropping the packet.
>> >>
>> >> Fix arp_nd_ns_match() to add "eth.dst == ff:ff:ff:ff:ff:ff"
>> >> for IPv4 ARP and "eth.mcast" for IPv6 ND_NS.  This follows
>> >> the precedent set by commit c05c565548 which added the same
>> >> eth.dst restriction to the priority 75 self-originated ARP
>> >> flood flow in the same pipeline stage.
>> >>
>> >> After this fix, unicast ARP and ND requests for router-owned
>> >> IPs fall through to the L2_LKUP stage flows for direct L2
>> >> delivery.
>> >>
>> >> Reported-at: https://issues.redhat.com/browse/FDP-3885
>> >> Assisted-by: Claude Opus 4.6, Claude Code
>> >> Signed-off-by: Dumitru Ceara <[email protected]>
>> >> ---
>> >> NOTE: this depends on 1872d61e34aa ("northd: Use MC_UNKNOWN for
>> >> broadcast ARP requests.") which is only present on the main branch.
>> >> For backporting this fix to 26.03 we'd have to backport its dependency
>> >> too.
>> >> ---
>> >>  northd/northd.c     |   7 +-
>> >>  tests/ovn-northd.at | 265
>> ++++++++++++++++++++++++--------------------
>> >>  tests/ovn.at        | 206 ++++++++++++++++++++++++++++++++++
>> >>  3 files changed, 358 insertions(+), 120 deletions(-)
>> >>
>>
>> ...
>>
>> >>
>> >>
>> > Looks good to me, thanks.
>> >
>> > Acked-by: Ales Musil <[email protected]>
>> >
>>
>> Thanks for the review!  Applied to main.
>>
>> As this is a bug fix, I'd like to backport it to 26.03 but in order for
>> it to function properly we'd also need to backport its dependency,
>> 1872d61e34aa ("northd: Use MC_UNKNOWN for broadcast ARP requests.").
>>
>> Are there any objections for me doing that (maintainers in CC)?
>>
>
> No objections.
>

No objections.

Numan


>
>>
>> Regards,
>> Dumitru
>>
>>
> Thanks,
> Ales
>
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