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)?

Regards,
Dumitru

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