From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-x233.google.com (mail-wg0-x233.google.com [IPv6:2a00:1450:400c:c00::233]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 3CC1321F240 for ; Wed, 30 Apr 2014 01:19:53 -0700 (PDT) Received: by mail-wg0-f51.google.com with SMTP id z12so1341848wgg.22 for ; Wed, 30 Apr 2014 01:19:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=OE93zGoQxoTRBqdnWOoy/2bemxdorgjZ0J5sohyLHRo=; b=Ux0qNdx8USRDLRZdjKaMPSPSsFqwAiYDrS7rl69ruF8OTI7FOQxsgFMVuVNlRD4+EC AOQvJGSDX0iUVQma8UgnxlCi4DRbsDr3fMVr1TvoSma3Avm9Mp5gll+fm12GQOaQSANm 1EZmxX+phxc1nY6eHYIncqqEBH0BaC6215D/L5umjg/jZ3SgbEsqJ4wNymz09YFY1YxB vNfn1QAdRwuNGf0EsKq3i8OIKl+IXkGZHK+iP8/qVA0NkNJfdyDkkpFFdm7FtDH3IB3E RSaKk6MaQJHmgPF+o2fbeNg99aYd2bXYMCr1XiRQa++GEdkzWQsDyXOybtmKp+sLfpBw Vapg== MIME-Version: 1.0 X-Received: by 10.180.80.3 with SMTP id n3mr2406466wix.36.1398845991210; Wed, 30 Apr 2014 01:19:51 -0700 (PDT) Received: by 10.217.136.137 with HTTP; Wed, 30 Apr 2014 01:19:51 -0700 (PDT) In-Reply-To: <53609DFA.9040708@gmail.com> References: <4130D000-FE28-4A5E-B824-3371C1602472@cisco.com> <87bnvkkr2n.fsf@toke.dk> <53609DFA.9040708@gmail.com> Date: Wed, 30 Apr 2014 10:19:51 +0200 Message-ID: From: Pedro Tumusok To: Jan Ceuleers Content-Type: multipart/alternative; boundary=f46d0418253866d4ad04f83e36fb Cc: bloat Subject: Re: [Bloat] [aqm] the side effects of 330ms lag in the real world 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: Wed, 30 Apr 2014 08:19:53 -0000 --f46d0418253866d4ad04f83e36fb Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Wed, Apr 30, 2014 at 8:53 AM, Jan Ceuleers wrote= : > On 04/29/2014 07:01 PM, Toke H=C3=B8iland-J=C3=B8rgensen wrote: > > However, as that graph shows, it is quite possible to completely avoid > > bufferbloat by deploying the right shaping. And in that case fibre > > *does* have a significant latency advantage. The best latency I've seen > > to the upstream gateway on DSL has been ~12 ms. > > I am not an expert, but I believe that this is due to the use of > interleaving. This is a method to improve the strength of forward error > correction by spreading out the effects of impulse noise on DSL lines > across multiple reed-solomon-protected codewords at the expense of latenc= y. > > The topic is briefly discussed on the ADSL Wikipedia page. > Depending on the interleave depth you get extra latency. But there are also different schemes you can use Interleave, the one that basically came with ADSL. Phyr, Broadcom evolution on interleave, that has less latency, I believe, in most cases. G.INP, which I have been told is a standardized version of Phyr. All of these will affect the latency and by how much is also dependant on the configuration you have done on your DSLAM. To add to the mess, not all DSLAM's support phyr or g.inp and then up the complexity a bit with CPE that supports one, two or all three of the technologies. Ohh some ISPs might even not use interleave and just have the DSLAM setup to do Fastmode/Fastpath or what the vendor decided to name the feature. Pedro > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat > --=20 Best regards / Mvh Jan Pedro Tumusok --f46d0418253866d4ad04f83e36fb Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable



On Wed, Apr 30, 2014 at 8:53 AM, Jan Ceuleers <= ;jan.ceuleers@g= mail.com> wrote:
On 04/29/2014 07:01 PM, Toke= H=C3=B8iland-J=C3=B8rgensen wrote:
> However, as that graph shows, it is quite possible to completely avoid=
> bufferbloat by deploying the right shaping. And in that case fib= re
> *does* have a significant latency advantage. The best = latency I've seen
> to the upstream gateway on DSL has been ~12 ms.

I am not an expert, but I believe that this is due to the use of
interleaving. This is a method to improve the strength of forward error
correction by spreading out the effects of impulse noise on DSL lines
across multiple reed-solomon-protected codewords at the expense of latency.=

The topic is briefly discussed on the ADSL Wikipedia page.
=

Depending on the interleave depth you get extra latency= . But there are also different schemes you can use

Interleave, the one that basically came with ADSL.
Phyr, Bro= adcom evolution on interleave, that has less latency, I believe, in most ca= ses.
G.INP, which I have been told is a standardized version of P= hyr.

All of these will affect the latency and by how much is= also dependant on the configuration you have done on your DSLAM. To add to= the mess, not all DSLAM's support phyr or g.inp and then up the comple= xity a bit with CPE that supports one, two or all three of the technologies= .

Ohh some ISPs might even not use interleave and just ha= ve the DSLAM setup to do Fastmode/Fastpath or what the vendor decided to na= me the feature.

Pedro




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Bloat mailing list
Bloat@lists.bufferbloat.net<= /a>
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--
= Best regards / Mvh
Jan Pedro Tumusok

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