Re: [PATCH net-next 3/6] bridge: Add selective forwarding of gratuitous neighbor announcements

[Nikolay Aleksandrov <razor@blackwall.org>]

On 03/05/2026 10:35, Danielle Ratson wrote:
> The existing neighbor suppression unconditionally suppresses gratuitous
> ARPs and unsolicited Neighbor Advertisements, which prevents fast
> mobility of hosts between VTEPs.
> 
> Add the neigh_forward_grat option to allow selective control of gratuitous
> neighbor announcements. When neigh_suppress is enabled but
> neigh_forward_grat is disabled (default), gratuitous announcements are
> suppressed. When neigh_forward_grat is enabled, gratuitous announcements
> are forwarded while regular neighbor discovery remains suppressed.
> 
> The implementation provides per-output-port control by:
> 1. Adding a 'grat_arp' flag to BR_INPUT_SKB_CB to mark gratuitous ARPs and
>     unsolicited NAs.
> 2. Setting both grat_arp and proxyarp_replied flags in
>     br_do_proxy_suppress_arp() and br_do_suppress_nd() when gratuitous
>     packets are detected.
> 3. Checking neigh_forward_grat per output port during flooding:
>     - For gratuitous ARPs/NAs: suppress unless the output port has
>       neigh_forward_grat enabled.
>     - For regular ARPs/NDs: maintain existing behavior.
> 
> This allows gratuitous announcements from any input port to be selectively
> forwarded based on each output port's individual neigh_forward_grat
> setting, enabling gratuitous neighbor announcements to be flooded to the
> VXLAN fabric.
> 
> Regular neighbor discovery (ARP requests, NS queries, solicited replies)
> remains controlled by neigh_suppress and is unaffected.
> 
> Signed-off-by: Danielle Ratson <danieller@nvidia.com>
> Reviewed-by: Ido Schimmel <idosch@nvidia.com>
> Reviewed-by: Petr Machata <petrm@nvidia.com>
> ---
>   net/bridge/br_arp_nd_proxy.c | 22 ++++++++++++++++++++++
>   net/bridge/br_forward.c      | 15 +++++++++++----
>   net/bridge/br_private.h      |  2 ++
>   3 files changed, 35 insertions(+), 4 deletions(-)
> 

Acked-by: Nikolay Aleksandrov <razor@blackwall.org>