Re: [aqm] Status of the GSP AQM?

Jonathan Morton <chromatix99@gmail.com> Fri, 15 December 2017 20:04 UTC

Return-Path: <chromatix99@gmail.com>
X-Original-To: aqm@ietfa.amsl.com
Delivered-To: aqm@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id BD118126C19 for <aqm@ietfa.amsl.com>; Fri, 15 Dec 2017 12:04:37 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.449
X-Spam-Level:
X-Spam-Status: No, score=-2.449 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=gmail.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 3r55G9OczGCi for <aqm@ietfa.amsl.com>; Fri, 15 Dec 2017 12:04:35 -0800 (PST)
Received: from mail-qk0-x231.google.com (mail-qk0-x231.google.com [IPv6:2607:f8b0:400d:c09::231]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id ED064124D6C for <aqm@ietf.org>; Fri, 15 Dec 2017 12:04:34 -0800 (PST)
Received: by mail-qk0-x231.google.com with SMTP id 8so11772644qkj.3 for <aqm@ietf.org>; Fri, 15 Dec 2017 12:04:34 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=mYL0WdXwpwv74rL6XhA78PHyyZF3DO1KcX+T3we5a94=; b=k0kxMbpdhqkGMSdue4VPMd/W+qGZgOvMv8fU4FAq+nIYH9NNSkYHTqjR/nILu5CxCX qHmu32CiiaWY7/TynZrCShEvQFR3yNtrEnuOLeagJmhRW4NhawCRgH+vhK6lQm0/o7FU wYTs/LS3Use7LZNwNTgcRalZMicccRmOvL17SxhTtApK7CJmujUadG395WyfPhlvOObO i/yCPKtZ2QBkLzz8ctjgLVef/spTukxNoQ9NTpVpl/okYXWU2bodLS/OBADbL2rCJvh4 1NMs539Q6Szjv4aJiHsztuxCrX4DaEGL/E/thys0+3w3sfxnUfgZSJFbzpmImcjKNRG+ uVdA==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=mYL0WdXwpwv74rL6XhA78PHyyZF3DO1KcX+T3we5a94=; b=OfkLoIKX3l/vpoe/HiG5eC3U67LBwShanfFm9FiJodgKXI3SFrV/0dO2UWjqixutyt gdeA38wkNrqATZ+zIM9GCTRrzqrfFWVHE+VVwPv1K6wmYSwLNa1VYMIwEw20SDOIynuB RrIdpeUWAJ10P/6hk7kpMU3kMI8qqVDNdgaVatpSt8tH/US8AizFRQcbtXLUijP4ZbjS oBysvpBansh+7x1Mr32Ivm/2LG3gPR6Vwzbo4WUX67MIyejRM8j52p/S6nTbfsPZGlNW roapbWT0Y4i/d4pgZXoVS4pEPZh3QWST3JuPyWTc9HdH4365CLs8hz91kAOeTSYcYRTp Q+Qg==
X-Gm-Message-State: AKGB3mKBlqB4TeKnf8qX5v6MbDu0obVg/Q59FPI7PRwB48i6VT4f6Tjk 0hqUpCY5s37/uBEq4hbM2FPGfQvK54UvS0Hyw8I=
X-Google-Smtp-Source: ACJfBosqU1+SRSNwHkDNoxpXH5YgTxMr2F/Z8+Zsc8QPYq+cAYl18IR0mFyacgWH0UfnpuprrX0zGFMAo1wWiDil0EQ=
X-Received: by 10.55.214.203 with SMTP id p72mr3131909qkl.284.1513368273999; Fri, 15 Dec 2017 12:04:33 -0800 (PST)
MIME-Version: 1.0
Received: by 10.140.102.179 with HTTP; Fri, 15 Dec 2017 12:04:33 -0800 (PST)
Received: by 10.140.102.179 with HTTP; Fri, 15 Dec 2017 12:04:33 -0800 (PST)
In-Reply-To: <CAJq5cE3QNQ1qrn8T37rmqOKh1Q0KQFGf1p5ZoxxJ5Tpwb8mdXw@mail.gmail.com>
References: <468c391d-7e18-e67c-d1b6-b6526eb8d9e3@kit.edu> <6cbdb8fb-4a4f-9fdf-e391-081c9bf94a1f@mti-systems.com> <1b67c68b-00de-6cb2-cca1-5b9d06b58714@kit.edu> <DB4PR07MB425231D6D323F2B4B6F09ADE90B0@DB4PR07MB425.eurprd07.prod.outlook.com> <CAJq5cE30GqXkFUv9J8tH8rnq3qeL+DUi=e4rVp3DdMiNgTh3rA@mail.gmail.com> <DB4PR07MB4259163AC5445D2F57637BFE90B0@DB4PR07MB425.eurprd07.prod.outlook.com> <CAJq5cE2YEYxwMRVcvXm9Ag6dxasnN8xhrrzjLknH881BNVbfyw@mail.gmail.com> <CAJq5cE3QNQ1qrn8T37rmqOKh1Q0KQFGf1p5ZoxxJ5Tpwb8mdXw@mail.gmail.com>
From: Jonathan Morton <chromatix99@gmail.com>
Date: Fri, 15 Dec 2017 22:04:33 +0200
Message-ID: <CAJq5cE12ppojYX6i9emQ4QbVrRWbS5a0cBR+5gxSXAMV2tMVXw@mail.gmail.com>
To: "Francini, Andrea (Nokia - US/Murray Hill)" <andrea.francini@nokia-bell-labs.com>
Cc: Roland Bless <roland.bless@kit.edu>, Wesley Eddy <wes@mti-systems.com>, "aqm@ietf.org" <aqm@ietf.org>, "Lautenschlaeger, Wolfram (Nokia - DE/Stuttgart)" <wolfram.lautenschlaeger@nokia-bell-labs.com>
Content-Type: multipart/alternative; boundary="001a1147995a62dcb405606682b2"
Archived-At: <https://mailarchive.ietf.org/arch/msg/aqm/7ZpA40K2cDjysbvA44ke-n1ETb8>
Subject: Re: [aqm] Status of the GSP AQM?
X-BeenThere: aqm@ietf.org
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: "Discussion list for active queue management and flow isolation." <aqm.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/aqm>, <mailto:aqm-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/aqm/>
List-Post: <mailto:aqm@ietf.org>
List-Help: <mailto:aqm-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/aqm>, <mailto:aqm-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 15 Dec 2017 20:04:38 -0000

On 15 Dec 2017 19:19, "Francini, Andrea (Nokia - US/Murray Hill)" <
andrea.francini@nokia-bell-labs.com>; wrote:
>
> If “conjunction with flow isolation” means combination of the algorithm
with a flow queueing arrangement, there is logically no restriction in
realizing it. We tested FQ-GSP on ns2, getting similar results as with
other FQ-AQM schemes (never worse, never overwhelmingly better in the
scenarios we looked at). Since the algorithmic simplicity is not as
critical in lower-speed links, we thought there was little value in trying
to add one more scheme to an already crowded space.

Perhaps a better wording would be, "it seems very unlikely to outperform
existing AQMs in conjunction with FQ".

> Also (and this is just my opinion), I don’t think that combining FQ and
AQM is a good idea, because it imposes a single policy on all flows despite
the variety of their needs. I like a plain FQ with large buffer much
better, because it guarantees bandwidth fairness and makes every
application solely responsible for the queuing delay it gets.

I have a couple of compelling arguments in favour of an AQM-FQ combination:

1: ECN aware flows are able to avoid incurring packet losses, by receiving
and acting on information about link congestion when they reach their
fair-share throughput.  That should be music to the ears of those industry
members who are apparently allergic to packet loss.

2: When it is unfortunately necessary to put the shaper downstream of the
physical bottleneck link (ie. when consumers must compensate for an ISP's
bufferbloat), AQM is the only reliable way to keep the bottleneck queue
empty.  Combining it with FQ ensures that only the saturating flows receive
congestion signals and potentially lose packets.

- Jonathan Morton