From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-x22a.google.com (mail-ob0-x22a.google.com [IPv6:2607:f8b0:4003:c01::22a]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id BC37D21F1D2 for ; Thu, 21 Mar 2013 11:01:38 -0700 (PDT) Received: by mail-ob0-f170.google.com with SMTP id wc20so3198647obb.29 for ; Thu, 21 Mar 2013 11:01:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=KKrbD/yeGlRbVgDATGzD6sYgtZDq6Ng1ieElEubglno=; b=gjlmaztO7gUewlZE1YiflpdKpNd6ypeXmzOIYoW0rJ42HtmMt6za9H1V5vrbE/FIRm at87pQyW3XnRD7eaHhPI26ETVoZcTT9xSFH+O2fHF4BN89T8UKj89VGU9JK9s+X7YDHA nYV7l1xN19QAjB5vXM//qd666XHtRleypUL4qBwjE273dcj/5zQ1WlWEJT+OwYo+xOjG +14LpL9/3CmyKVZDOAnNZtOmxAFBf7dpMM7MAOOjGbzzw2lscSm/v6dvHJsvUXSmNb4m jZU7p6bYJcM5hq0+v6ei14oj9d/3fB48yoVP4KsrtITomj9eTrIPAxMh6dYAVPCa3PuY gEzg== MIME-Version: 1.0 X-Received: by 10.182.192.3 with SMTP id hc3mr7323049obc.41.1363888897515; Thu, 21 Mar 2013 11:01:37 -0700 (PDT) Sender: gettysjim@gmail.com Received: by 10.76.22.193 with HTTP; Thu, 21 Mar 2013 11:01:37 -0700 (PDT) In-Reply-To: <514B484F.2070902@net.t-labs.tu-berlin.de> References: <51408BF4.7090304@cisco.com> <8C48B86A895913448548E6D15DA7553B7D020F@xmb-rcd-x09.cisco.com> <514B484F.2070902@net.t-labs.tu-berlin.de> Date: Thu, 21 Mar 2013 14:01:37 -0400 X-Google-Sender-Auth: 6dykhrSvdCTxRRww4B-_11wcCR4 Message-ID: From: Jim Gettys To: Oliver Hohlfeld Content-Type: multipart/alternative; boundary=f46d041fa0c53fe5a304d87321ea Cc: "tsvwg@ietf.org" , bloat 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 18:01:39 -0000 --f46d041fa0c53fe5a304d87321ea Content-Type: text/plain; charset=ISO-8859-1 On Thu, Mar 21, 2013 at 1:50 PM, Oliver Hohlfeld < oliver@net.t-labs.tu-berlin.de> wrote: > (cross posting to bloat) > > On 03/13/2013 04:28 PM, Fred Baker (fred) wrote: > > On Mar 13, 2013, at 10:23 AM, 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 > >> > >> Eliot > > > > Well, yes, he says that in his gigabit FTTH network he doesn't see > megabit-scale problems. > > Marks paper is /not/ about measuring buffer bloat in an FTTH network. > While he uses the FTTH network as /vantage point/, the paper actually > measures buffer bloat in various remote networks. > > Marks paper is not the only study suggesting the extend of the problem > to be modest. The presented results are in line with recent findings by > Chirichella and Rossi [1]. Based on unpublished work, I can confirm the > low magnitude of the problem. I analyzed passive measurements of > residential users traffic from multiple continents (~60 million IPs > originating from 50\% of all ASes) and rarely find excessive RTTs that, > among other problems, can indicate the presence of buffer bloat. > I believe you are actually measuring the *fraction of the time* your measurements show bad latency, rather than the fraction of paths that may suffer from significant bufferbloat at various times due to excessive buffering. Buffers only fill when they are being used and that only happens when saturation occurs. The best data I've seen on how widespread the problem is is the ICSI Netalyzr scatter plots results, which (in color) are in my blog. http://gettys.wordpress.com/2010/12/06/whose-house-is-of-glasse-must-not-throw-stones-at-another/ These must be flavored by understanding that those tests top out at about 20Mbps, and that (to keep the time that netalzyr takes to run sane) stops at about 5 seconds of buffering. I encourage everyone to run netalyzr and/or the mlabs tests for bufferbloat on your own broadband connections, or do simple copy and ping tests inside your own house over wifi to your local file servers.... - Jim > In summary, bloated buffers exist and buffer bloat can be demonstrated, > but current findings suggest that it rarely occurs in practice. One > potential reason being that users do not often sustainably utilize > their uplink capacity and fill-up their potentially large queues. > > Oliver > > [1] To the Moon and back: are Internet bufferbloat delays really that > large? > http://perso.telecom-paristech.fr/~drossi/paper/rossi13tma-a.pdf > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat > --f46d041fa0c53fe5a304d87321ea Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable




On Thu, Mar 21, 2013 at 1:50 PM, Oliver = Hohlfeld <oliver@net.t-labs.tu-berlin.de> wrote= :
(cross posting to bloat)

On 03/13/2013 04:28 PM, Fred Baker (fred) wrote:
> On Mar 13, 2013, at 10:23 AM, Eliot Lear <lear@cisco.com> 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. =A0Yo= u can
>> find a reference to that paper at the following URL:
>>
>> http://www.sigcomm.org/ccr/papers/2013/January/2= 427036.2427041
>>
>> Eliot
>
> Well, yes, he says that in his gigabit FTTH network he doesn't see= megabit-scale problems.

Marks paper is /not/ about measuring buffer bloat in an FTTH network.
While he uses the FTTH network as /vantage point/, the paper actually
measures buffer bloat in various remote networks.

Marks paper is not the only study suggesting the extend of the problem
to be modest. The presented results are in line with recent findings by
Chirichella and Rossi [1]. Based on unpublished work, I can confirm the
low magnitude of the problem. I analyzed passive measurements of
residential users traffic from multiple continents (~60 million IPs
originating from 50\% of all ASes) and rarely find excessive RTTs that,
among other problems, can indicate the presence of buffer bloat.

I believe you are actuall= y measuring the *fraction of the time* your measurements show bad latency, = rather than the fraction of paths that may suffer from significant bufferbl= oat at various times due to excessive buffering.=A0

Buffers= only fill when they are being used and that only happens when saturation o= ccurs.

The best data I've seen on how widespread the problem is is the ICSI Ne= talyzr scatter plots results, which (in color) are in my blog. =A0http://gettys.wordpress.com/2010/12/06/whose-ho= use-is-of-glasse-must-not-throw-stones-at-another/=A0 These must be fla= vored by understanding that those tests top out at about 20Mbps, and that (= to keep the time that netalzyr takes to run sane) stops at about 5 seconds = of buffering.

I= encourage everyone to run netalyzr and/or the mlabs tests for bufferbloat = on your own broadband connections, or do simple copy and ping tests inside = your own house over wifi to your local file servers....
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 =A0- Jim


In summary, bloated buffers exist and buffer bloat can be demonstrated,
but current findings suggest that it rarely occurs in practice. One
potential reason being that users do not often sustainably utilize
their uplink capacity and fill-up their potentially large queues.

Oliver

[1] To the Moon and back: are Internet bufferbloat delays really that large= ?
http://perso.telecom-paristech.fr/~drossi/paper/rossi13= tma-a.pdf
_______________________________________________
Bloat mailing list
Bloat@lists.bufferbloat.net<= /a>
= https://lists.bufferbloat.net/listinfo/bloat

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