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Thu, 06 Nov 2025 03:47:51 -0800 (PST) Received: from [192.168.88.32] ([212.105.155.83]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-429eb49c2fdsm4632849f8f.39.2025.11.06.03.47.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 06 Nov 2025 03:47:50 -0800 (PST) Message-ID: <981dbc10-0833-418e-b389-93e0daee8acf@redhat.com> Date: Thu, 6 Nov 2025 12:47:48 +0100 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 net-next 08/14] tcp: accecn: retransmit downgraded SYN in AccECN negotiation To: chia-yu.chang@nokia-bell-labs.com, edumazet@google.com, parav@nvidia.com, linux-doc@vger.kernel.org, corbet@lwn.net, horms@kernel.org, dsahern@kernel.org, kuniyu@google.com, bpf@vger.kernel.org, netdev@vger.kernel.org, dave.taht@gmail.com, jhs@mojatatu.com, kuba@kernel.org, stephen@networkplumber.org, xiyou.wangcong@gmail.com, jiri@resnulli.us, davem@davemloft.net, andrew+netdev@lunn.ch, donald.hunter@gmail.com, ast@fiberby.net, liuhangbin@gmail.com, shuah@kernel.org, linux-kselftest@vger.kernel.org, ij@kernel.org, ncardwell@google.com, koen.de_schepper@nokia-bell-labs.com, g.white@cablelabs.com, ingemar.s.johansson@ericsson.com, mirja.kuehlewind@ericsson.com, cheshire@apple.com, rs.ietf@gmx.at, Jason_Livingood@comcast.com, vidhi_goel@apple.com References: <20251030143435.13003-1-chia-yu.chang@nokia-bell-labs.com> <20251030143435.13003-9-chia-yu.chang@nokia-bell-labs.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20251030143435.13003-9-chia-yu.chang@nokia-bell-labs.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/30/25 3:34 PM, chia-yu.chang@nokia-bell-labs.com wrote: > From: Chia-Yu Chang > > Based on AccECN spec (RFC9768), if the sender of an AccECN SYN > (the TCP Client) times out before receiving the SYN/ACK, it SHOULD > attempt to negotiate the use of AccECN at least one more time by > continuing to set all three TCP ECN flags (AE,CWR,ECE) = (1,1,1) on > the first retransmitted SYN (using the usual retransmission time-outs). > > If this first retransmission also fails to be acknowledged, in > deployment scenarios where AccECN path traversal might be problematic, > the TCP Client SHOULD send subsequent retransmissions of the SYN with > the three TCP-ECN flags cleared (AE,CWR,ECE) = (0,0,0). > > Signed-off-by: Chia-Yu Chang Acked-by: Paolo Abeni