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[78.154.15.182]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-48a7c30f856sm13683255e9.21.2026.04.29.02.04.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 29 Apr 2026 02:04:07 -0700 (PDT) Message-ID: Date: Wed, 29 Apr 2026 12:04:04 +0300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next 1/2] bridge: Do not suppress ARP probes and DAD NS unconditionally Content-Language: en-US, bg To: Danielle Ratson , netdev@vger.kernel.org Cc: idosch@nvidia.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, shuah@kernel.org, bridge@lists.linux.dev, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20260429062405.1386417-1-danieller@nvidia.com> <20260429062405.1386417-2-danieller@nvidia.com> From: Nikolay Aleksandrov In-Reply-To: <20260429062405.1386417-2-danieller@nvidia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 29/04/2026 09:24, Danielle Ratson wrote: > When neighbor suppression is enabled on a VXLAN port, the bridge is > expected to reply to ARP/NS messages on behalf of remote hosts when both > FDB and neighbor entries exist. This allows the bridge to suppress > flooding of these messages to the VXLAN overlay. > > According to RFC 9161 ("Operational Aspects of Proxy ARP/ND in Ethernet > Virtual Private Networks"): > "A PE SHOULD reply to broadcast/multicast address resolution messages, > i.e., ARP Requests, ARP probes, NS messages, as well as DAD NS messages. > An ARP probe is an ARP Request constructed with an all-zero sender IP > address that may be used by hosts for IPv4 Address Conflict Detection as > specified in [RFC5227]". > > However, the current implementation unconditionally suppresses ARP probes > and DAD Neighbor Solicitations, which breaks Duplicate Address Detection > (DAD) over EVPN. > > For DAD to work correctly over the VXLAN fabric: > - When the bridge does not know the answer: > flood the probe/DAD packet to allow remote VTEPs to respond. > - When the bridge knows the answer: > reply to indicate the address is in use. > > Fix by adjusting the early suppression checks to exclude ARP probes and > DAD NS from unconditional suppression. > > When replying to a DAD NS, br_nd_send() is adjusted to set the NA > destination to the all-nodes multicast address (ff02::1) and clear the > Solicited flag, in accordance with RFC 4861 section 7.2.4. > > Reviewed-by: Ido Schimmel > Signed-off-by: Danielle Ratson > --- > net/bridge/br_arp_nd_proxy.c | 16 +++++++++++----- > 1 file changed, 11 insertions(+), 5 deletions(-) > Acked-by: Nikolay Aleksandrov