From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-x231.google.com (mail-ob0-x231.google.com [IPv6:2607:f8b0:4003:c01::231]) (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 C78DD21F1F0 for ; Thu, 21 Mar 2013 13:05:58 -0700 (PDT) Received: by mail-ob0-f177.google.com with SMTP id eh20so3231819obb.8 for ; Thu, 21 Mar 2013 13:05:58 -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=jGmoyfkI3MbOGods205iQk3YI8u/jEZsd+uYAK0PuF8=; b=wXCwxFVslxSTjy1Y0lhw1n3TiJZbVGqSL5CxG5DK46aLqdEZeQZ+cgMsWVJFyRiMIf LBSg+2XoNkIS2RpBLApAqmhXvheX5lXx2sJAU3Wad9KXTpvYWrOrXzd7kuOKIVpJNp6s eJSGeKVG/gj47ff8C/H2j91OEtpFfLgoq+xFJujPn1U7gr4pqRng1+7Vul0o1owhBdwA Mdd7zD3E9x5zCbh+xnKC8bmzbmBB0JDKhP7dfJ7UAN1O+R9h8HhVFrHCJGP5ZyF2kn0Z ek9YekGZvNV7z1Rzzs4dMW8kNf9PAxbwqTCX5lSwi4rRA4X381TMy3hzrAs0eeud1HD9 vG3Q== MIME-Version: 1.0 X-Received: by 10.60.8.197 with SMTP id t5mr8042836oea.4.1363896357820; Thu, 21 Mar 2013 13:05:57 -0700 (PDT) Sender: gettysjim@gmail.com Received: by 10.76.22.193 with HTTP; Thu, 21 Mar 2013 13:05:57 -0700 (PDT) In-Reply-To: References: <51408BF4.7090304@cisco.com> <514B5AC8.8000502@net.t-labs.tu-berlin.de> Date: Thu, 21 Mar 2013 16:05:57 -0400 X-Google-Sender-Auth: 0GxwoNfDeDAObHFLinCVUe_nOVk Message-ID: From: Jim Gettys To: Mikael Abrahamsson Content-Type: multipart/alternative; boundary=e89a8fb1ef42eb2bc604d874ddf7 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 20:05:59 -0000 --e89a8fb1ef42eb2bc604d874ddf7 Content-Type: text/plain; charset=ISO-8859-1 Also, Windows XP is still significantly in use in the Internet (unfortunately). On Thu, Mar 21, 2013 at 3:25 PM, Mikael Abrahamsson wrote: > On Thu, 21 Mar 2013, Oliver Hohlfeld wrote: > > In summary, the question on how much of a problem buffer bloat currently >> is cannot be fully answered and still requires further research. >> > > Buffer bloat is a problem on basically all access forms apart from ETTH. > Usually ETTH is produced using L2 or L3 switches with very small buffers (5 > ms or so), and policing is used instead of buffering for limiting service > rate. This means high speed TCP flows will sawtooth their performance over > time because of large amount of consecutive drops, meaning low bw > interactive flows are less impacted. > > So it's my belief that your measurements means most people don't actually > put congestion pressure on their accesses, thus the large buffers are > seldom used and you're not seeing buffering. Due to the fact TCP window scaling is off by default in Windows XP, the most a single TCP connection will have in flight on Windows XP is 64K bytes. This both limits the ability of a Windows XP system to saturate a link in the first place (thereby sometimes avoiding filling buffers at the bottleneck at all), and limits the amount of latency a single TCP connection will inflict. Every more modern TCP can easily fill any sized buffer given time with a single TCP connection. - Jim > > > -- > Mikael Abrahamsson email: swmike@swm.pp.se > > ______________________________**_________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/**listinfo/bloat > --e89a8fb1ef42eb2bc604d874ddf7 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Als= o, Windows XP is still significantly in use in the Internet (unfortunately)= .



On Thu, Mar 21, 2013 at 3:25 PM, Mikael = Abrahamsson <swmike@swm.pp.se> wrote:
On Thu, 21 Mar 2013, Oliver Hohlfeld wrote:

In summary, the question on how much of a problem buffer bloat currently is= cannot be fully answered and still requires further research.

Buffer bloat is a problem on basically all access forms apart from ETTH. Us= ually ETTH is produced using L2 or L3 switches with very small buffers (5 m= s or so), and policing is used instead of buffering for limiting service ra= te. This means high speed TCP flows will sawtooth their performance over ti= me because of large amount of consecutive drops, meaning low bw interactive= flows are less impacted.

So it's my belief that your measurements means most people don't ac= tually put congestion pressure on their accesses, thus the large buffers ar= e seldom used and you're not seeing buffering.


Due to the fact TCP windo= w scaling is off by default in Windows XP, the most a single TCP connection= will have in flight on Windows XP is 64K bytes.

This both limits the ability of a Wi= ndows XP system to saturate a link in the first place (thereby sometimes av= oiding filling buffers at the bottleneck at all), and limits the amount of = latency a single TCP connection will inflict.

Every m= ore modern TCP can easily fill any sized buffer given time with a single TC= P connection.
= =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0- Ji= m


--
Mikael Abrahamsson =A0 =A0email: swmike@swm.pp.se

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