netdev - Re: [PATCH v9 net-next 07/15] tcp: accecn: retransmit downgraded SYN in AccECN negotiation

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Message-ID: <CANn89iKKQH=moYMied14AHrsDTOKK0pM4kVQHdh1FS4WcnU7ww@mail.gmail.com>
Date: Tue, 20 Jan 2026 11:22:20 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: chia-yu.chang@...ia-bell-labs.com
Cc: pabeni@...hat.com, parav@...dia.com, linux-doc@...r.kernel.org, 
	corbet@....net, horms@...nel.org, dsahern@...nel.org, kuniyu@...gle.com, 
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	Jason_Livingood@...cast.com, vidhi_goel@...le.com
Subject: Re: [PATCH v9 net-next 07/15] tcp: accecn: retransmit downgraded SYN
 in AccECN negotiation

On Mon, Jan 19, 2026 at 7:59 PM <chia-yu.chang@...ia-bell-labs.com> wrote:
>
> From: Chia-Yu Chang <chia-yu.chang@...ia-bell-labs.com>
>
> 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 <chia-yu.chang@...ia-bell-labs.com>
> Acked-by: Paolo Abeni <pabeni@...hat.com>
>

Please amend the changelog to give the RFC precise relevant chapter
(3.1.4.1 if I am not mistaken)

Reviewed-by: Eric Dumazet <edumazet@...gle.com>