From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf1-x12d.google.com (mail-lf1-x12d.google.com [IPv6:2a00:1450:4864:20::12d]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id B9A7F3B29E for ; Tue, 6 Apr 2021 17:36:26 -0400 (EDT) Received: by mail-lf1-x12d.google.com with SMTP id 12so24887451lfq.13 for ; Tue, 06 Apr 2021 14:36:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=djCcQ6pAmTyFHSINX0kUZxgmnDiFBsRYylLz9f5fSpE=; b=Jjb6r64VJaYuhPFZeB5tGY6cTIPHLyWvgsimmaxFkS3tlZEPdDACKHDBwdDyojcUcd s/EO1GSOoPxcB18Q7ynUhfmqlVmBsf4l3tkCK8Bru2j+HydCMglwZtfgkwJPYrbdu4ML wvMg6B4OS4z/3L2STV1vqJG2MVgwdu0pvgE2qZ5qon30URYAS9IuCiCURHLEJYb6WPBX GzMzKpIT7FZ6C9wdjKT2zejP/Kgcl3YnqqwPME3ojzhEeD6Ew5Cnn0BLF0DBCc0oGx3E C4wpNaYuHFUu+pYfaTuYlU4aH6e5qnneiNwf+ozE2ME//eFHOgg+bejmN8+NrIkTXemF HBKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=djCcQ6pAmTyFHSINX0kUZxgmnDiFBsRYylLz9f5fSpE=; b=RRx11pS08Tn1UvQ65+PpRvN3FPgUHg/HXCj+vYCV/6YKULi6ofGEhsUppk0ylCXYt6 NcSDCM8/1JgOhuZqgVI+L+yIx4YYKOC+EzUL0pBeJC3m2ImLOHmFQ7xoNdEvaY5U/Xgy BBsk1NjpB0YIoFIz7jG2JHOSDCP1LI7nPL6RoRW9ey3yenC0vuzvrO1y5cmps95axKI/ Pwmls6CMiSbT3a3kZJacHRYx1zFwtpuF6g6HPatQ1axugl5KzUGuLUN1jnN7hCGpn587 Gco7THfv8RTnJJmfH0Hl89FFMhQ1y+52liXiy+e5X4k5hftgTBK5KDt9j7sFagJaaAze qEfg== X-Gm-Message-State: AOAM532+Pq0lc6p+JKrWqTcP5H71DzRkOdAbhH2H6xiYA5iyROIyRied MXOdiZod/yfrjaGaoie2QiE= X-Google-Smtp-Source: ABdhPJx76YVSLXmgutBI7DNhCXqmiQ8FDrp8Ch8Sf8BQuA79hKx1M07vpcc/0DP6M9mMeWaTjjlOew== X-Received: by 2002:ac2:46d9:: with SMTP id p25mr105919lfo.601.1617744985705; Tue, 06 Apr 2021 14:36:25 -0700 (PDT) Received: from jonathartonsmbp.lan (178-55-25-11.bb.dnainternet.fi. [178.55.25.11]) by smtp.gmail.com with ESMTPSA id t5sm2325965ljc.78.2021.04.06.14.36.24 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 06 Apr 2021 14:36:25 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.7\)) From: Jonathan Morton In-Reply-To: <2C969F6A-660D-4806-8D46-5049A2E96F74@gmx.de> Date: Wed, 7 Apr 2021 00:36:23 +0300 Cc: "Bless, Roland (TM)" , bloat@lists.bufferbloat.net Content-Transfer-Encoding: quoted-printable Message-Id: <02488D80-24C0-42E6-A4C6-81F7402DC58E@gmail.com> References: <9A233C8C-5C48-4483-A087-AA5FE1011388@gmail.com> <320ECDF6-8B03-4995-944B-4726B866B2D3@gmx.de> <20210406004735.GA16266@unix-ag.uni-kl.de> <31F4A461-F3D6-42FF-B6A5-33F4824F97BC@gmx.de> <033d63b1-8c7e-751a-5768-96ffcd825fce@kit.edu> <2C969F6A-660D-4806-8D46-5049A2E96F74@gmx.de> To: Sebastian Moeller X-Mailer: Apple Mail (2.3445.9.7) Subject: Re: [Bloat] Questions for Bufferbloat Wikipedia article X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 06 Apr 2021 21:36:27 -0000 > On 7 Apr, 2021, at 12:30 am, Sebastian Moeller = wrote: >=20 > I still think that it is not completely wrong to abstractly say BBR = evaluates RTT changes as function of the current sending rate to probe = the bottlenecks capacity (and adjust its sending rate based on that = estimated capacity), but that might either indicate I am looking at the = whole thing at too abstract a level, or, as I fear, that I am simply = misunderstanding BBR's principle of operation... It might be more accurate to say that it estimates the delivery rate at = the receiver by observing the ack stream, and aims to match that with = the send rate. There is some periodic probing upwards to see if a = higher delivery rate is possible, followed by a downwards drain cycle = which, I think, pays some attention to the observed RTT. And there is = also a cwnd mechanism overlaid as a safety valve. Overall, it's very much a hybrid approach. - Jonathan Morton=