From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from millet.cc.columbia.edu (millet.cc.columbia.edu [128.59.72.250]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 0E0EC2007D0 for ; Fri, 6 Mar 2015 11:46:23 -0800 (PST) Received: from hazelnut (hazelnut.cc.columbia.edu [128.59.213.250]) by millet.cc.columbia.edu (8.13.8/8.13.8) with ESMTP id t26Jh5V8018851 for ; Fri, 6 Mar 2015 14:46:21 -0500 Received: from hazelnut (localhost.localdomain [127.0.0.1]) by hazelnut (Postfix) with ESMTP id 08A626D for ; Fri, 6 Mar 2015 14:46:21 -0500 (EST) Received: from paneer.cc.columbia.edu (paneer.cc.columbia.edu [128.59.29.4]) by hazelnut (Postfix) with ESMTP id E5E166D for ; Fri, 6 Mar 2015 14:46:20 -0500 (EST) Received: from mail-qc0-f182.google.com (mail-qc0-f182.google.com [209.85.216.182]) by paneer.cc.columbia.edu (8.14.4/8.14.3) with ESMTP id t26JkKNF000051 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for ; Fri, 6 Mar 2015 14:46:20 -0500 (EST) Received: by qcxr5 with SMTP id r5so53239291qcx.10 for ; Fri, 06 Mar 2015 11:46:20 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:content-type:mime-version:subject:from :in-reply-to:date:cc:message-id:references:to; bh=w0F5gE+PGgps4151GZUDBLXXSYJeEP69vmSdtbWCktk=; b=KSL8V/dLiE3Lz6fwbW7bGGNVRsAPlseszaj+cO8QuQCErfO1rNooHuXpwhn79r1+H8 GZaVBA1A6EA7xOFB4k9vYPTQl4tMDtUSYlMHzaCe7YqKUEVhMAm1WWGTP7NcntwyB+Km kt6zx7JtrbnZ3pxhiMqsXpPK7Wjv12ipmq/Ssz5ZdvlK1lYGY6+N8yO9JdlPpMpEeUNm /OPxSlahPuynJc9shKLlwEPLw7l1Jo4pkyFZx8tvz47udQldkjaUZZ76vBbL1fL8At9Z 8aHsm1m/aBpl9pcVe7M4ZsKdoGU2hjRC6siSRycfSQjIYFAfSOtgrC9WnghjVEymo1/D 2aEg== X-Gm-Message-State: ALoCoQkslfx24QKkONJkfPXyRpgQ4iEV2t62luN4aA+ugZFm5d0Syfa7m1fSjWCtisQiQIblqTp/G9f60P/nLAQqi4unYDKoPf/baVS2iZWtEjShxHBV5f0PdLV/AL9hTVhqeYcyaArnC94Ujt0chwbcgrKOs47n9A== X-Received: by 10.229.80.3 with SMTP id r3mr21867384qck.23.1425671180311; Fri, 06 Mar 2015 11:46:20 -0800 (PST) X-Received: by 10.229.80.3 with SMTP id r3mr21867369qck.23.1425671180126; Fri, 06 Mar 2015 11:46:20 -0800 (PST) Received: from ?IPv6:2001:18d8:ffff:16:c878:1c08:7c77:6b10? ([2001:18d8:ffff:16:c878:1c08:7c77:6b10]) by mx.google.com with ESMTPSA id l37sm4911963qkh.9.2015.03.06.11.46.17 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 06 Mar 2015 11:46:18 -0800 (PST) Content-Type: multipart/alternative; boundary="Apple-Mail=_E3255D03-82D0-4BF7-82E4-907E93507E79" Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2087\)) From: Vishal Misra In-Reply-To: Date: Fri, 6 Mar 2015 14:46:14 -0500 Message-Id: References: <473265656416337848@unknownmsgid> To: Dave Taht X-Mailer: Apple Mail (2.2087) X-No-Spam-Score: Local X-Scanned-By: MIMEDefang 2.68 on 128.59.29.4 X-Mailman-Approved-At: Thu, 12 Mar 2015 07:41:04 -0700 Cc: "aqm@ietf.org" , bloat Subject: Re: [Bloat] the cisco pie patent and IETF IPR filing 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: Fri, 06 Mar 2015 19:46:52 -0000 --Apple-Mail=_E3255D03-82D0-4BF7-82E4-907E93507E79 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Hi Dave, > On Mar 5, 2015, at 8:58 AM, Dave Taht wrote: >=20 > I let the data take me where it may. I (not) always have, but reformed > about 15 years ago. [1] I hope that you and your students also, do > some experiments on the successors to PI and RED and DRR - and also > follow the data where-ever it leads you. In 2003 we had published a paper on STPI (Self-Tuning PI). The = self-tuning design accounted for variations in link capacity, presence = of cross traffic (i.e. unregulated UDP flows) and variations in the = number of flows being controlled. We also proved the (local, = exponential) stability of our self-tuning mechanism. The paper is available at = http://dna-pubs.cs.columbia.edu/citation/paperfile/79/GLOBECOM_2003_STAQM.= pdf This was an evolution over our first PI design where we introduced the = concept of linear controllers for AQM. BTW STPI is not PIE, the differences as I see them are (1) STPI explicitly accounts for cross traffic. (2) STPI tunes the parameters continuously, over the entire range of = loss (marking) rates unlike PIE which seems to be doing it for 3 = specific values chosen ahead of time. (3) The stability of the adaptive mechanism of STPI was rigorously = proven in a linearized setting.=20 (4) The tradeoff between stability and responsiveness for the time = constant of adaptation was made explicit. (5) STPI does not, as the author of PIE stated recently "control the = offset to the reference level and second moment of the latency = independently=E2=80=9D. STPI simply controls the latency, I don=E2=80=99t = know of any way to control the second moment of any reference signal by = a linear controller like PI(E), but then I do not know the details of = PIE. It was a very deliberate design choice by us to introduce a linear = controller like PI for AQM because of ease of implementation. We = could=E2=80=99ve gone the route of optimal and/or non-linear controllers = but we didn=E2=80=99t. As a side note, we also designed a self-tuning version of RED that we = called STRED (different from ARED) but RED suffers from some fundamental = limitations so exploring that won=E2=80=99t be of interest. So I am getting STPI and PI implemented as part of cerowrt and will = release the code for anyone to play with/evaluate. More than anything, it is the increased deployment of ECN that has = revived an interest in AQM for me. -Vishal -- http://www.cs.columbia.edu/~misra/ --Apple-Mail=_E3255D03-82D0-4BF7-82E4-907E93507E79 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 Hi Dave,

On Mar 5, 2015, at 8:58 AM, Dave Taht <dave.taht@gmail.com>= wrote:

I let the data take me where it may. I (not) = always have, but reformed
about 15 years ago. [1] I = hope that you and your students also,  do
some experiments on the successors to PI and RED = and DRR - and also
follow the data where-ever = it leads you.


In = 2003 we had published a paper on STPI (Self-Tuning PI). The self-tuning = design accounted for variations in link capacity, presence of cross = traffic (i.e. unregulated UDP flows) and variations in the number of = flows being controlled. We also proved the (local, exponential) = stability of our self-tuning mechanism.

The paper is available at http://dna-pubs.cs.columbia.edu/citation/paperfile/79/GLOBECOM_= 2003_STAQM.pdf

This was an evolution over our first PI design where we = introduced the concept of linear controllers for AQM.

BTW STPI is not PIE, the = differences as I see them are

(1) STPI explicitly accounts for cross = traffic.
(2) STPI tunes the parameters = continuously, over the entire range of loss (marking) rates unlike PIE = which seems to be doing it for 3 specific values chosen ahead of = time.
(3) The stability of the adaptive mechanism = of STPI was rigorously proven in a linearized setting. 
(4) The tradeoff between stability and responsiveness for the = time constant of adaptation was made explicit.
(5) = STPI does not, as the author of PIE stated recently "control the offset = to the reference level and second moment of the = latency independently=E2=80=9D. STPI simply controls the latency, I = don=E2=80=99t know of any way to control the second moment of any = reference signal by a linear controller like PI(E), but then I do not = know the details of PIE. It was a very deliberate design choice by us to = introduce a linear controller like PI for AQM because of ease of = implementation. We could=E2=80=99ve gone the route of optimal and/or = non-linear controllers but we didn=E2=80=99t.

As a side note, we also designed a = self-tuning version of RED that we called STRED (different from ARED) = but RED suffers from some fundamental limitations so exploring that = won=E2=80=99t be of interest.

So I am getting STPI and PI implemented = as part of cerowrt and will release the code for anyone to play = with/evaluate.

More than anything, it is the increased deployment of ECN = that has revived an interest in AQM for me.

-Vishal
--
http://www.cs.columbia.edu/~misra/



= --Apple-Mail=_E3255D03-82D0-4BF7-82E4-907E93507E79--