From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.17.20]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 1B0193B2A4; Mon, 7 Aug 2023 06:18:19 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.de; s=s31663417; t=1691403495; x=1692008295; i=moeller0@gmx.de; bh=IE5xYZTuR9Rp6Lrl7weFcZDHSYMWfrzGXbkGnQ7nT9k=; h=X-UI-Sender-Class:Subject:From:In-Reply-To:Date:Cc:References:To; b=uTTvu+915cQ8Nr1rCNacXsq+NaPiqsVBQs8JUdPUEiIn5GYEbRp1P1ajMtRZ64/0wlxzqqR IfGWaVPVbALB14ueTOKE+JsJZFj+ANQbOpX3mKantghw1IQGsVqwLsDXSg83nldCPtGriBGeO JVNDRth1Bq6SSUggIpzlKF5HjlrM0HSodFsLJpQ9Wpn8NwAMoRfo52MobYl8LKCkJ2lSvhvd6 L831RB6yvn/LQ97Ox/sGGB/c8ZaTjxU4R48ICFvUW0k3gI8EnkwoTCORj9/B0GV/DpAoSX/J+ CniI69Ive8imuO5cgpGJ94JaLu6QhWCOvNHIcHVb/Ok7aICOkZiw== X-UI-Sender-Class: 724b4f7f-cbec-4199-ad4e-598c01a50d3a Received: from smtpclient.apple ([134.76.241.253]) by mail.gmx.net (mrgmx105 [212.227.17.168]) with ESMTPSA (Nemesis) id 1MwQTF-1pdK8A3833-00sJSM; Mon, 07 Aug 2023 12:18:15 +0200 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.4\)) From: Sebastian Moeller In-Reply-To: <6392cb1d-92e5-f289-c684-5850bf87df4a@kit.edu> Date: Mon, 7 Aug 2023 12:18:14 +0200 Cc: =?utf-8?Q?Dave_T=C3=A4ht?= , bloat , codel@lists.bufferbloat.net Content-Transfer-Encoding: quoted-printable Message-Id: <61DEDE16-34C9-430E-BEED-0D52E1F92132@gmx.de> References: <6392cb1d-92e5-f289-c684-5850bf87df4a@kit.edu> To: "Bless, Roland (TM)" X-Mailer: Apple Mail (2.3696.120.41.1.4) X-Provags-ID: V03:K1:lZrIQ2NYHx8ijB+uaCmxiT7U8ZSWg2VEt6HWHO4xmaHD73HUUOd 6EERMologPALKYtpmtWbWONB8+i/dRr0YeQftzB4xeXPxqDN7liTpTuwl1LxV5cL8um1HKv vquZTtZ8Kg30HMrct7Mm5JdO5z8qKjzBO7vU8d5wB88rJKh1LJ2+4VJD4/W6Hv+yXdPDNei RgVrzAWbBq77bisvzHhFg== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:Z2GTyNxt430=;Jw5Yid+8YcJurquy4uJ6xm9YHch /ygDvn3iP5UQQ1s5kEWpXOJoqmZVAiKn8uviSNtDCgSOpQ1Ca11+VOqmCFMzHnN5oexoQBy0T 8/Yz8CpZkaZQI8yxJweI5BP8Y1TQBFplS/HX/1W0popc6KCNMDmVyCzFaoS6d40+/9wylHF3u nTk1JYW8kiIDzmM4iwVfuY39j4xSZ1vgGzMJ9vy7Bp4T6QLmrmFixAp7PaVODdkGwq2jwupW+ 61PoR8S7Hw2QG6zjKSdpt42o0zJ0cn5L0gBzuZfQJ8/CSvC4axLw1jU0/0f8Jg/SqxJgjHf0D p091C7kSSOLNMHJ/IOWwmft0nXk0N5p3CQ2rB38utswVL8HSSUYhD3E+d+Cj0mCgPWn4THJpt sQeprddFzo04WGp4xyxvCH3xyU6TTFWYbnAocc4dWzUA7qzpzAw9UpE5geR7h/ux1xou2Uw4Q pT+mPlXtPXU3AX71EjcGBGScdJM1tb3rBCbWb+sfMO7nYQqRd48pa1PVq9IAukDBySCSN0kj1 fuvtM6HmKzaiv4eyNPkzX+ls7gSg7mSmd/5Upm0wQHOVzl+Y9M24TYMSuHb56GKLxPQzFsdzN 0NNVQCsl+8Z2mTGnkyYzI2044tin7Z6uAv5A5+IEmzKDHiNApyqPP2P5k3cRENDbZYggwsOQL /UwXnNJwJXuJiS3fh28Z4M5m2spN0k3hoIVpkCuc0z0cdNJCoSxeA0Qg2JBgVWjtAZkkZVKHC 3p5ra+jiNNzJeknDc3s+uNx1gGzv0s18KGOzzXBEGkF0HHznpAaNZs2OPf5++KkwAjDyneFBJ yYq5l0EJ233zaGDuWEeINWDTnKUd968RiGa81u/2XXwxLKLs2IuodmtijH4LWVBTV3PTIjkgo VBK576bwxnxjuuuTdTA+Osxod47n0k2qiu7QKNS1ZAcxdti2ETKDjG8dl2jTuwDUDyDx5UDGa xewcQda+8Mu4oN47p9liYhEzUrM= Subject: Re: [Bloat] slow start: small chunks can talk 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: Mon, 07 Aug 2023 10:18:20 -0000 Hi Roland. > On Aug 7, 2023, at 10:48, Bless, Roland (TM) via Bloat = wrote: >=20 > Hi Dave, >=20 > On 01.08.23 at 00:36 Dave Taht via Bloat wrote: >> Promising approach: >> https://ieeexplore.ieee.org/document/10188775 >=20 > It's a pity that neither the authors nor the reviewers were aware of = earlier related work that you also sent here to the list: >=20 > L. Guo and J. Y. B. Lee, "TCP-FLASH - A Fast Reacting TCP for Modern = Networks," in IEEE Access, vol. 9, pp. 68861-68879, 2021, doi: = 10.1109/ACCESS.2021.3077612. Interesting link. This still uses essentially a packet-pair = measuring method (send packet back2back, look at time difference in = resulting ACK packets to estimate bottleneck bandwidth in the forward = direction). These are still not robust or reliable... (parallel path, = reordering, or simply congestion on the reverse path, ACK filtering, ACK = compression by GRO on the receiver end, ...). Now, well possible that = packet-pair data, while not perfect, might still be good enough for the = intended purpose... And even for a traditional slow-start having an = educated guess when to leave the exponential growth phase could be = helpful... More over, let's assume any of these (let's short circuit the = probing phase) will actually be deployed at scale; how will the network = cope with the much more aggressive ramp-up of such flows (essentially = initial-window as one batch the switch to estimated capacity once the = bottleneck rate is estimated). It is fun to see a single/few of such = flows do the right thing, but what about having the majority of flows = use such methods? (Which will likely invalidate the bottleneck rate = estimate quickly). I guess I might be too cautious here, but I personally see the = exponential ramp-up in more traditional slow-start already as pretty = aggressive and yet more adaptive to changing capacity than jumping to = the estimated capacity essentially cold (I have similar hesitation with = the careful resume internet draft). Regards Sebastian P.S.: "To tackle this problem, FLASH is designed to suppress the AWnd constraint unless it is zero. This opportunistic transmission technique, first proposed by Liu and Lee [6], allows FLASH to send data beyond the AWnd limit up to CWnd amount of packets inflight. " This is quite an euphemism "opportunistic transmission technique" for = simply ignoring parts of the protocol... P.P.S.: Dave's link is behind a pay-wall, so I have no idea about that = paper beyond the abstract... but if they also relay on packet-pair = bandwidth estimates and an faster-than-slow-start ramp-up, I would = expect similar issues. >=20 > The fast launch phase and especially the CWnd-Compensated Bandwidth = Estimator (CCBE) are quite similar and a comparison of both approaches > would have been interesting... >=20 > Regards, > Roland >=20 > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat