From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-x236.google.com (mail-lj1-x236.google.com [IPv6:2a00:1450:4864:20::236]) (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 6230F3CB35 for ; Thu, 19 Jul 2018 15:16:46 -0400 (EDT) Received: by mail-lj1-x236.google.com with SMTP id q5-v6so9017567ljh.12 for ; Thu, 19 Jul 2018 12:16:46 -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=KyXbmGJu6q1wdfi7nQWDqY1CTEV385ClCB/6e8dScVo=; b=k8LjoFzeS7w3+k/8ENSdftx77KifNWE5EU1WtYC/apM0oMRM8tsX6pktChZGw/wyQ7 ISjxaNLKQplg3zzYLvpC+IU+Q6EgImc/WFOA7IImMOUmczvu/OFtIfZWHcf55SZcap7J c13ibLB2NezT3aFUAuH05eQsx/V73wmmPY/Z2auKhA1/KhYFErDsMD3oU/AygrPBi8b8 8lO3Ekfh70u8TShL4soqnq+Os6fc4IeP7fauaPdYJEWRaSyE+VXqmyN4pnEYL0TJOJ2A M+8Hjv3BM+wqSfopfdUv/CXwItRSDJOGXtfp5BhczdzYj6siN/M7JMGUqzZMFN2tQ9kh qbeA== 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=KyXbmGJu6q1wdfi7nQWDqY1CTEV385ClCB/6e8dScVo=; b=RkeQZI/f3ATJhe5+RSpvGmqBDVxNFBu2mEyeJdo7RAHulXFXNwkvNzYIVhxUCuLdGD IMX4H0t+EIlj+lLQ+3XpfZLiKWBE4QEqLDr7KiyMmxr1k6UqxZQ7bi6+FRVNAWutkZbS eClZXVbVa5TNvVWWn1BFi5i0qgTilmvaYnqREzC1a4jWJJUeNIAiJfAEvF7XBt6M2fUa Cljw0zoOkeCxoets+52ynE07RSFz3oZthco2KzpjVBwxE9DQ//6tvAqv+9KOsDz+ijCT oeJCOt+O/8M2wU8JxLE/K87dLkdOOyFYbIASnd53G7foGGjQYR3HKXBw0pBuRpcKsUud XN/Q== X-Gm-Message-State: AOUpUlEDpSDLCfhBc8awRlMVkf1UwcF4YuEAuabbMlC5P/IIM74q+Y+Q N/BTO12CtPj76UiQ1O4JEJ2KE1pU X-Google-Smtp-Source: AAOMgpefePiJPXFu5dCcnwvNWPHD2GRu4SiDMnA1v40lWiLM53eOtlYE6s+qfYhPNScQzAhxgh1Mqw== X-Received: by 2002:a2e:3a0e:: with SMTP id h14-v6mr8402911lja.20.1532027805310; Thu, 19 Jul 2018 12:16:45 -0700 (PDT) Received: from [192.168.239.216] (83-245-233-124-nat-p.elisa-mobile.fi. [83.245.233.124]) by smtp.gmail.com with ESMTPSA id 13-v6sm1209878ljx.2.2018.07.19.12.16.44 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 19 Jul 2018 12:16:44 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) From: Jonathan Morton In-Reply-To: <42959aa5-a266-bd75-a49b-38a726695f11@pollere.com> Date: Thu, 19 Jul 2018 22:16:43 +0300 Cc: codel@lists.bufferbloat.net Content-Transfer-Encoding: quoted-printable Message-Id: <521F7AA2-5FE5-401F-964B-61F34C86A8FF@gmail.com> References: <42959aa5-a266-bd75-a49b-38a726695f11@pollere.com> To: Kathleen Nichols X-Mailer: Apple Mail (2.3445.9.1) Subject: Re: [Codel] self tuning codel X-BeenThere: codel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: CoDel AQM discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 19 Jul 2018 19:16:46 -0000 > On 19 Jul, 2018, at 10:04 pm, Kathleen Nichols = wrote: >=20 >> Thus, we let a specific AQM router serve >> as a centralized DR in the system. All routers send packet >> dropping probability updates to DR. DR then updates its list >> of packet dropping probabilities and sends it to all routers >=20 > Does this seem possible to anyone? There's an inherent assumption here > that "dropping probabilities" are constant over a period of time that = is > long compared to the time to do the above. In what I've seen of = traffic > and AQMs this seems unlikely but I'm certainly not as well-informed on > this as some people. Based on the above, the approach seems completely wrong-headed to me. = AQM should not be centralised, but must act according to local = conditions. Certainly such a system would be impossible to deploy in a = heterogeneous environment like the Internet. >> every AQM router >> needs to know all the packet dropping probabilities at the >> bottleneck links in order to compute the window sizes of the >> flows from (5). As a first approximation, you can assume that if you are the bottleneck, = nobody else on the same path is, and therefore their drop probabilities = are all zero. This assumes only that you're dealing with traffic that's = responsive to congestion signals, as TCP is. Transient conditions may = exist where the assumption isn't entirely correct, but these are *only* = transient. The situation for UDP may of course be different. - Jonathan Morton