From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-x22d.google.com (mail-oi0-x22d.google.com [IPv6:2607:f8b0:4003:c06::22d]) (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 67E7B3B2C7 for ; Wed, 21 Sep 2016 15:45:59 -0400 (EDT) Received: by mail-oi0-x22d.google.com with SMTP id r126so72814735oib.0 for ; Wed, 21 Sep 2016 12:45:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=oN8oUJzJ4r4CtZAPkt1XOrvGzTWlYsvDmH4FApdLsnU=; b=YH7UOS75OUW+Fsxyp/dt/2L2J2pisY9nZOoFs0P94qjY0wEkPoYJbEU3T4X3T7lwLT Y6Kd/x5sPkp0IMvYD9e7XvfRfv2QttH2wPyxVAky/DvAaIVfTGAqz0a3J4SLK5ZOaGWe nNVkIv7VhWMBH02r6IPMK7vCIYD0ghZWxKslg73UocO0QBpz+90bA1zuhn61as+Uyw5J NWM5t+Cq1zwRo9KYqkPCAvUx9oqFXpenNBdi3hxVgiQJRRLgPTP3OD8NWM/jxWCPqzrp P+n6Ckw56NeVuLtpYn0ZVYXhuewanHZ70n26kLAX/B71/UgETMsY3iuE58ic57rJw9Mg ck7w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=oN8oUJzJ4r4CtZAPkt1XOrvGzTWlYsvDmH4FApdLsnU=; b=O4Wsog51sUQQX861aBEfDOxM0/g5/X78E1Rm3sr9T0kVXOnvRBJEBlodQ1hVh0zCMZ Sk1KZJR+yRcUwLsGAs24v7Dy4vYs7sRSW2O/LqqCrdwoA+ShecZHRcycER3qTzZkVRPG VAP9dBl93DDK6FSMIV/MKG3/ISTysKXn4YbWEnnTPysNUvPXCJfVqPaTcZvyhyL7QN09 +zY9kgBsK9CfnQfp7gek12AcljrK0iiYNcTnZRSFz4FlSWf+GSqiGyDmaywkGdQmpO+T YHKZmhPCI1NFQEFS91+JN0DaZiMsHc35b75qVheBqQAcm0cJcR3N5y0ZeC9KdpFT6ppP d5Jw== X-Gm-Message-State: AE9vXwNQjUCgzKTbdo6WyK7GIzRSc4G+FS+JzEwE6jYC8X9tDOC0eTo+5Kti2oAuArdpWTG79JkykoLU8G/DajYq X-Received: by 10.202.228.136 with SMTP id b130mr42988485oih.109.1474487158627; Wed, 21 Sep 2016 12:45:58 -0700 (PDT) MIME-Version: 1.0 Received: by 10.202.182.65 with HTTP; Wed, 21 Sep 2016 12:45:28 -0700 (PDT) In-Reply-To: References: From: Neal Cardwell Date: Wed, 21 Sep 2016 15:45:28 -0400 Message-ID: To: Dave Taht Cc: Mikael Abrahamsson , bloat , "cerowrt-devel@lists.bufferbloat.net" , BBR Development Content-Type: text/plain; charset=UTF-8 Subject: Re: [Cerowrt-devel] [bbr-dev] taking apart BBR's behaviors in flent X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Sep 2016 19:45:59 -0000 On Wed, Sep 21, 2016 at 3:25 PM, Dave Taht wrote: > > So it seems my intuition was wrong, at least for these scenarios. It wasn't > > CUBIC that would kill BBR, it's the other way around. > > My intuition was that "delay based TCPs can't work on the internet!" - > and was wrong, also. Keep in mind that BBR is not really "delay-based", at least in the traditional sense. BBR is not based on backing off in response to a single signal like loss or RTT increases. If BBR could be said to be "based" on any one thing, it's "model-based": it has a model of the network with two parameters: bottleneck bandwidth and round-trip propagation time. So delay increases do not always lead to a slower sending rate or lower volume of data in flight. For example, if the round-trip propagation delay increases but the bandwidth stays constant, BBR can actually increase the amount of data in flight in order to achieve its fair share of the bandwidth available in the longer pipe. Thanks for all this testing! neal