Re: [multipathtcp] MPTCP Schedulers

Olivier Bonaventure <olivier.bonaventure@uclouvain.be> Mon, 18 February 2019 19:51 UTC

Return-Path: <olivier.bonaventure@uclouvain.be>
X-Original-To: multipathtcp@ietfa.amsl.com
Delivered-To: multipathtcp@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 8C64C130F3E for <multipathtcp@ietfa.amsl.com>; Mon, 18 Feb 2019 11:51:23 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.001
X-Spam-Level:
X-Spam-Status: No, score=-2.001 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=uclouvain.be
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 bkisDtRAyDRE for <multipathtcp@ietfa.amsl.com>; Mon, 18 Feb 2019 11:51:21 -0800 (PST)
Received: from EUR03-VE1-obe.outbound.protection.outlook.com (mail-eopbgr50125.outbound.protection.outlook.com [40.107.5.125]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 3B661130F00 for <multipathtcp@ietf.org>; Mon, 18 Feb 2019 11:51:21 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=uclouvain.be; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=CuDcCYVyMhLZjgNEV8gpGB/W0DNQ0u0FjOa7ucLkwbE=; b=DQLbCudRoSnYBxJ4WcBEir5s5dAXxNkCC8IrIe36IoK7NeXXVthmRc7P2arZI6A2E6qKa3S3Rhci3bAhyOB1QA7YfdT2OeXPsy+UQYKojYj0suL3ML1lBStjXZerkC25vjq4y0DfwOHTD79nQcML6QCy2H7ypVhTTgq4cB9g5e8=
Received: from DB7PR03MB4170.eurprd03.prod.outlook.com (20.176.232.207) by DB7PR03MB4508.eurprd03.prod.outlook.com (20.176.234.144) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.1622.19; Mon, 18 Feb 2019 19:51:18 +0000
Received: from DB7PR03MB4170.eurprd03.prod.outlook.com ([fe80::3d22:a229:1259:ad1b]) by DB7PR03MB4170.eurprd03.prod.outlook.com ([fe80::3d22:a229:1259:ad1b%5]) with mapi id 15.20.1622.020; Mon, 18 Feb 2019 19:51:18 +0000
From: Olivier Bonaventure <olivier.bonaventure@uclouvain.be>
To: Vladimir Olteanu <vladimir.olteanu@cs.pub.ro>, Alexander Frömmgen <alexander@froemmgen.de>, Christoph Paasch <cpaasch=40apple.com@dmarc.ietf.org>
CC: "multipathtcp@ietf.org" <multipathtcp@ietf.org>
Thread-Topic: AW: [multipathtcp] MPTCP Schedulers
Thread-Index: AQHUxTRoWIUwCTLGU0CsNE7Slx9UQKXhKC8AgAKysACAABVFAIAB7R4AgAAe7YA=
Date: Mon, 18 Feb 2019 19:51:18 +0000
Message-ID: <f408c74c-ab58-3a24-d485-6a741a9987b2@uclouvain.be>
References: <a939bc37-16ed-9d8a-15d7-16dfec630290@cs.pub.ro> <20190215180722.GR1880@MacBook-Pro-19.local> <41d2eef4-67e8-62a5-5d05-b6248d2293e5@uclouvain.be> <1MKd92-1gcaMb0Y7I-00Kxa3@mrelayeu.kundenserver.de> <386d0bef-8eb0-b3ee-44bd-4ab17147be79@cs.pub.ro>
In-Reply-To: <386d0bef-8eb0-b3ee-44bd-4ab17147be79@cs.pub.ro>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-clientproxiedby: PR0P264CA0012.FRAP264.PROD.OUTLOOK.COM (2603:10a6:100::24) To DB7PR03MB4170.eurprd03.prod.outlook.com (2603:10a6:10:13::15)
authentication-results: spf=none (sender IP is ) smtp.mailfrom=olivier.bonaventure@uclouvain.be;
x-ms-exchange-messagesentrepresentingtype: 1
x-originating-ip: [2a02:2788:484:2c2:5461:b9cd:96fb:be1b]
x-ms-publictraffictype: Email
x-ms-office365-filtering-correlation-id: 781cc3c4-9b56-47e8-05e3-08d695da72d6
x-microsoft-antispam: BCL:0; PCL:0; RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600110)(711020)(4605104)(2017052603328)(7153060)(7193020); SRVR:DB7PR03MB4508;
x-ms-traffictypediagnostic: DB7PR03MB4508:
x-microsoft-exchange-diagnostics: 1;DB7PR03MB4508;23: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
x-microsoft-antispam-prvs: <DB7PR03MB45081E7F263DAB303D60346A86630@DB7PR03MB4508.eurprd03.prod.outlook.com>
x-forefront-prvs: 09525C61DB
x-forefront-antispam-report: SFV:NSPM; SFS:(10019020)(376002)(366004)(136003)(39860400002)(346002)(396003)(199004)(189003)(6486002)(305945005)(25786009)(186003)(316002)(110136005)(68736007)(6506007)(71200400001)(8936002)(53936002)(6246003)(256004)(6436002)(4326008)(81166006)(81156014)(93886005)(53546011)(6512007)(2906002)(71190400001)(8676002)(5660300002)(386003)(6116002)(229853002)(7736002)(102836004)(86362001)(31686004)(14454004)(31696002)(446003)(76176011)(478600001)(74482002)(486006)(106356001)(105586002)(97736004)(2616005)(11346002)(786003)(46003)(52116002)(36756003)(99286004)(476003); DIR:OUT; SFP:1102; SCL:1; SRVR:DB7PR03MB4508; H:DB7PR03MB4170.eurprd03.prod.outlook.com; FPR:; SPF:None; LANG:en; PTR:InfoNoRecords; A:1; MX:1;
received-spf: None (protection.outlook.com: uclouvain.be does not designate permitted sender hosts)
x-ms-exchange-senderadcheck: 1
x-microsoft-antispam-message-info: SrfIzxYOfh/ud4Rq6DQNNKUetU5Qh3q7wP7LGTePFxRq+Cg8K9+6swif4fGwUb2sUERRXOJWVuMPYo2dbpVd7DcQ4eOt3PvX22QnvYbg/L02yhk12b1+4ovDw53/CMM69ElBSTZSe2D6Z5htt8r7PERj9wLV94J/KxnimoyBfsajNhvj7t+WOnFaAKsjtgupvoRlmF9WkPdxmqtYPCSnJQx8cAhNZdYzj7/b/uQbNts9T5azCdH2ElIuAwJNgbyoYxIBMPdkYt/3DWK0/AQ+agltUSLoZv0RQc/WhkpFT/IrHcS7S6Ysr1dxReyL4OBrH4lAOHZew61pqUeX0RKq+w2YX/MJlBNXHWJlXYScYU1I5+IPeOTiDY+rHbv2yvYmTdHIaANkzW9vVx0u89jybC/C1nAyvxedQPPmr+paCeE=
Content-Type: text/plain; charset="utf-8"
Content-ID: <BB0146A30C06294388996BB87CB09F89@eurprd03.prod.outlook.com>
Content-Transfer-Encoding: base64
MIME-Version: 1.0
X-OriginatorOrg: uclouvain.be
X-MS-Exchange-CrossTenant-Network-Message-Id: 781cc3c4-9b56-47e8-05e3-08d695da72d6
X-MS-Exchange-CrossTenant-originalarrivaltime: 18 Feb 2019 19:51:17.9310 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-id: 7ab090d4-fa2e-4ecf-bc7c-4127b4d582ec
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB7PR03MB4508
Archived-At: <https://mailarchive.ietf.org/arch/msg/multipathtcp/SDOGR1ILZpfQTONox_8hQ_qj2mw>
Subject: Re: [multipathtcp] MPTCP Schedulers
X-BeenThere: multipathtcp@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Multi-path extensions for TCP <multipathtcp.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/multipathtcp>, <mailto:multipathtcp-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/multipathtcp/>
List-Post: <mailto:multipathtcp@ietf.org>
List-Help: <mailto:multipathtcp-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/multipathtcp>, <mailto:multipathtcp-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 18 Feb 2019 19:51:23 -0000

Vlad,
> 
> On 2/17/2019 2:35 PM, Alexander Frömmgen wrote:
>> What level of scheduler standardization do you consider? While an 
>> informal description of the scheduler behavior should be feasible, I 
>> have the feeling that a detailed specification of the scheduler 
>> behavior is not possible, e.g., i) details of todays scheduler 
>> behaviors emerged from the dependencies to the Linux Kernel (round 
>> trip time is calculation, packet queues), and ii) intuitive 
>> descriptions, such as "redundant“, are very imprecise (prefer old or 
>> new packets for heterogenous subflow environments?). [0]
> 
> At the very least we should write a general description of the three 
> algorithms that are available, what to expect from them and in which 
> cases they are best suited.

Round-Robin was a proof of concept that Christoph wrote to describe the 
flexibility of the modular implementation. I don't think that anyone 
really considers to use it in production.

The redundant scheduler was proposed in a paper, but again I'm not aware 
of anyone using it in production.

The default one is the lowest rtt first. It has been tuned over the 
years, but we could describe it in a draft.

There are other schedulers that are used and would be worth documenting 
in an IETF draft.

> 
> In the absence of such a document, I'd have to include said descriptions 
> in the SOCKS draft, which isn't the best place to go looking for such 
> information.

We can prepare something before Prague based on the existing papers. 
However, the description will remain abstract and may not include all 
the details that have been added to the Linux kernel implementation over 
the years.

It would be more interesting to document the use cases that operators 
would want to have as schedulers.


Olivier