Re: Multipath (was: Re: Re-chartering for extension work)

Olivier Bonaventure <olivier.bonaventure@tessares.net> Wed, 18 December 2019 18:40 UTC

Return-Path: <olivier.bonaventure@tessares.net>
X-Original-To: quic@ietfa.amsl.com
Delivered-To: quic@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 949F3120AC8 for <quic@ietfa.amsl.com>; Wed, 18 Dec 2019 10:40:04 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.9
X-Spam-Level:
X-Spam-Status: No, score=-1.9 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=tessares-net.20150623.gappssmtp.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 G9qMByGGs-WZ for <quic@ietfa.amsl.com>; Wed, 18 Dec 2019 10:40:01 -0800 (PST)
Received: from mail-wr1-x432.google.com (mail-wr1-x432.google.com [IPv6:2a00:1450:4864:20::432]) (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 7F4C1120967 for <quic@ietf.org>; Wed, 18 Dec 2019 10:40:01 -0800 (PST)
Received: by mail-wr1-x432.google.com with SMTP id y17so3421329wrh.5 for <quic@ietf.org>; Wed, 18 Dec 2019 10:40:01 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tessares-net.20150623.gappssmtp.com; s=20150623; h=mime-version:subject:from:in-reply-to:date:cc:message-id:references :to:content-transfer-encoding; bh=RGuh/9awoOlOVjrhgwprfW/hmC+pBuuWc7GL6F2saMg=; b=OUKFLh8wbRpTMO6+Ox/4aCNfoOR1X2UCSEJh92KGjv15a8qXkfD4+o7V7i2WKwqHwX cgGr322NIsH4FqoI6E3bfDwcCJDiWyZQJevnpBMuoUDG+wCXA5ZRQKeUm2SK1DDT1HB1 DbKgnpDj4jdWuw3WlDCRFw+dEbg3IzgfYBpOoKuuNNXbt5/vLo9K6+wpmxJi6XYbvdPH rSm+qqcdw1oWYxw+eo1QqKuuvw4Cnrp7NfS0qhmid3LnnZT3oY5j/ZfA6pJ78IUkDQTZ PlYe7UgRGWYk8tEf6aKy401AcO1pxoUSnkOKVvsFO6KmgfPuIXOzIhBQ7rlBgmGkhuCZ 0u0g==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :message-id:references:to:content-transfer-encoding; bh=RGuh/9awoOlOVjrhgwprfW/hmC+pBuuWc7GL6F2saMg=; b=D9Ni/cTW+cs1mS5NSDyu1QmV1ugChtwcu+LIFj7w9yncPEBCgn9NaN9AjDvgL5yQee KwVfl5ca4vp+1n6brPiH65uiAua2J+4Fktup35LNwhgUixoPYIc/Y5MjrDaIFDy56LJj 7+i6FHQNVslRO6QSHXJBtHSNkmRiJrx6i/St2dkO7ehNgQ+T05wlmUjUQPg8Rbxh7KKu Qs1rRmD1dn5Tx6IQESB93J/YYEcXrj712HYgp3eYq25pDGoVRPsDs3jNYIZ2UckX/ktN +2v4vQM6hDShiZWH04FOZH2ejTOs12kUui1v40dY9hsu56VmWzUnEZST+IpT/E2StPUD vLkw==
X-Gm-Message-State: APjAAAVBWKCE3QA/ASbatFik8siceiAJjoshRlHtH8DoUoUQaY32xofo UeGSBux1JiYpBMleOuAz3+RLF+PjkvZ6jPB0iXSkiOHeeBbjQG+IvlJVS0b7EpjxTSJP2ykQ
X-Google-Smtp-Source: APXvYqydM4kNYsTJXFNrOkCHyWiMN6kUTCakQnW91CN7aSIx8mPPT0J54HqwFrUjQZdXsiztAPJc0A==
X-Received: by 2002:adf:e78a:: with SMTP id n10mr4675231wrm.62.1576694399550; Wed, 18 Dec 2019 10:39:59 -0800 (PST)
Received: from ?IPv6:2001:6a8:308f:2:b864:3aa8:5c2f:4b10? ([2001:6a8:308f:2:b864:3aa8:5c2f:4b10]) by smtp.gmail.com with ESMTPSA id u14sm3547257wrm.51.2019.12.18.10.39.57 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 18 Dec 2019 10:39:57 -0800 (PST)
Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.11\))
Subject: Re: Multipath (was: Re: Re-chartering for extension work)
From: Olivier Bonaventure <olivier.bonaventure@tessares.net>
In-Reply-To: <CACpbDccdpKHygp87Be-ytC7juYZmUrfh-3a=4ESLCWMfE-t6Ww@mail.gmail.com>
Date: Wed, 18 Dec 2019 19:39:56 +0100
Cc: Christian Huitema <huitema@huitema.net>, Mikkel Fahnøe Jørgensen <mikkelfj@gmail.com>, Lars Eggert <lars@eggert.org>, Mark Nottingham <mnot@mnot.net>, IETF QUIC WG <quic@ietf.org>, Quentin De Coninck <quentin.deconinck@uclouvain.be>
Message-Id: <839F7E31-FB6A-4846-A3C4-C5539E14407E@tessares.net>
References: <A56547B6-2E3B-4ABE-8C9B-BA9ACC489FB2@mnot.net> <1E872371-F543-4822-8C11-05601913A72E@tessares.net> <752D0B90-8B29-4DBC-9B2F-09E834335598@eggert.org> <49366B32-6425-486C-9453-96D27E2E8EAE@tessares.net> <CAN1APdfNyMBzeWKVRQojo4W_mgxXSSwj4X4EvFC9Pfz4bZ+Pdg@mail.gmail.com> <DF4E42C3-3D90-4C68-989C-6B11833005F9@tessares.net> <CAN1APddWow_QBs+_6GRLyauWFrLVvcr7LA9Mjqdgw-Bcp0d=tQ@mail.gmail.com> <9bc43313-7a06-8b01-75ef-ff1c3925a6cc@huitema.net> <CACpbDccdpKHygp87Be-ytC7juYZmUrfh-3a=4ESLCWMfE-t6Ww@mail.gmail.com>
To: Jana Iyengar <jri.ietf@gmail.com>
X-Mailer: Apple Mail (2.3445.104.11)
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Archived-At: <https://mailarchive.ietf.org/arch/msg/quic/pOQWKYFbt9bFJgblh-jt2he-JlM>
X-BeenThere: quic@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Main mailing list of the IETF QUIC working group <quic.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/quic>, <mailto:quic-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/quic/>
List-Post: <mailto:quic@ietf.org>
List-Help: <mailto:quic-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/quic>, <mailto:quic-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 18 Dec 2019 18:40:04 -0000

Jana,

> On 18 Dec 2019, at 07:26, Jana Iyengar <jri.ietf@gmail.com> wrote:
> 
> 
> I'm not sure that this is the time for this conversation, but I'll share my thoughts since the question has been raised.
> 
> There will be quite some heavy lifting to do if we go down the path of designing a multipath extension for QUIC. We've seen this before. I worked on multipath for SCTP, which was quite some work. I remember when we started work on MPTCP at the IETF in 2009, and it was a lot more effort than most people anticipated. When we started work on connection migration for QUIC, we thought it might get done relatively quickly, but it was a feature that kept on giving.

For Multipath TCP, I would argue that most of the difficulty was caused by middleboxes.
> 
> None of this is to say that we shouldn't take on a hard problem, but before we start sliding into it, I would like to be convinced of its importance. We already have connection migration in the core drafts, and I'd like to see an articulation of the problems that multipath would solve in addition to basic migration. I would also like to see implementations that are keen to build it if an extension were to be developed, and applications that will use it. Without those, we would be putting the cart before the horse.
> 

I think that there are two clear use cases for a multipath transport. The first use case is ressource pooling as already mentioned by Lars. There are various situations where being able to use different paths simultaneously gives improved performance, in terms of delay or throughput. A common scenario is a dual-stack IPv4/IPv6 client that interacts with a dual-stack server through paths of different qualities. 

A second use case is for mobile devices that need to preserve connectivity while switching from one wireless network to another. When such a device detects another wireless network, it needs to bet whether migrating the connection to the new network would improve performance. With a multipath transport, there is no need to bet as the transport will automatically select the best performing network. Apple’s deployment of Multipath TCP is a good example of the benefits of such a multipath strategy.

Multipath was included in the QUIC charter to address such use cases.

Olivier


-- 


Disclaimer: https://www.tessares.net/mail-disclaimer/ 
<https://www.tessares.net/mail-disclaimer/>