From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.net.t-labs.tu-berlin.de (mail.net.t-labs.tu-berlin.de [IPv6:2001:470:96b9:4:130:149:220:252]) by huchra.bufferbloat.net (Postfix) with ESMTP id E721421F1E9 for ; Thu, 21 Mar 2013 12:08:57 -0700 (PDT) Received: from [IPv6:2001:470:96b9:1:14cb:af2e:2e24:2838] (ibis.net.t-labs.tu-berlin.de [IPv6:2001:470:96b9:1:14cb:af2e:2e24:2838]) by mail.net.t-labs.tu-berlin.de (Postfix) with ESMTPSA id 074004C4DF1; Thu, 21 Mar 2013 20:08:57 +0100 (CET) Message-ID: <514B5AC8.8000502@net.t-labs.tu-berlin.de> Date: Thu, 21 Mar 2013 20:08:56 +0100 From: Oliver Hohlfeld User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130106 Thunderbird/17.0.2 MIME-Version: 1.0 To: tsvwg@ietf.org, bloat References: <51408BF4.7090304@cisco.com> In-Reply-To: <51408BF4.7090304@cisco.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Bloat] [tsvwg] how much of a problem is buffer bloat today? X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 21 Mar 2013 19:08:58 -0000 On 03/13/2013 03:23 PM, Eliot Lear wrote: > I don't have an answer to that question, but Mark Allman from ICIR did > attempt to characterize buffer bloat on the Internet through an > empirical study that appeared in the January edition of CCR. You can > find a reference to that paper at the following URL: > > http://www.sigcomm.org/ccr/papers/2013/January/2427036.2427041 The full extend of the answer is still unclear to me. We have recently attempt to complement the rather technical and QoS centric view on the buffer bloat problem by estimating the user experience impact: BufferBloat: How Relevant? A QoE Perspective on Buffer Sizing. Oliver Hohlfeld, Enric Pujol, Florin Ciucu, Anja Feldmann, Paul Barford http://downloads.ohohlfeld.com/paper/bufferbloat-qoe-tr.pdf The paper studies the impact of buffer sizes on VoIP, IPTV, and web browsing Quality of Experience (QoE). We find that: - oversized buffers indeed degrade QoE when they are sustainable filled. - however, large buffers do not always degrade user experience. - the level of congestion significantly degrades QoE, oftentimes more than buffer sizes. One example discussed in the paper is web browsing. When the level of congestion is low, HTTP transactions benefit from "large" buffers as they reduce losses by absorbing transient bursts. When the level of congestion is high, transfer times become RTT dominated and the queuing delays start to kick in. Note that objective QoE metrics used in our paper also do not provide the full picture: (i) objective QoE metrics and subjective user experience are not always correlated. (ii) the influence memory effects is still unclear (e.g., for how long will a user be influenced by a single degradation and how does it alter his behavior?). Psychological insights are only available for short-time scales. (ii) even if service degradations exist that would degrade the user experience, the user might not always notice them. In summary, the question on how much of a problem buffer bloat currently is cannot be fully answered and still requires further research. Oliver