Re: [Int-area] WG Adoption Call: IP Fragmentation Considered Fragile

Brian E Carpenter <brian.e.carpenter@gmail.com> Wed, 25 July 2018 03:13 UTC

Return-Path: <brian.e.carpenter@gmail.com>
X-Original-To: int-area@ietfa.amsl.com
Delivered-To: int-area@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 749D4130F69; Tue, 24 Jul 2018 20:13:03 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2
X-Spam-Level:
X-Spam-Status: No, score=-2 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, 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 eMopyhRDe8jj; Tue, 24 Jul 2018 20:13:00 -0700 (PDT)
Received: from mail-pg1-x52f.google.com (mail-pg1-x52f.google.com [IPv6:2607:f8b0:4864:20::52f]) (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 73A20130F8B; Tue, 24 Jul 2018 20:12:53 -0700 (PDT)
Received: by mail-pg1-x52f.google.com with SMTP id p23-v6so4258670pgv.13; Tue, 24 Jul 2018 20:12:53 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=3g11L3dhad2k/v0WBXWSf2PoBpohQ9eEdqUzP6QB2AM=; b=By3P0J7qbCc0zU3ESjxqtwFQeNrnxZxvFSJMSFiHQXBVNturMh3gPaRTp8wwfeEodF 1rqDySaFAMsROvzh/HGD5CweZc5dtiRb895qlPiaDxI/jtu7/N/fcFjFk9FK2YGOxskV D5Wqg6dW0sdPvt9Q9EEl4VHtZ4KxXHDnlLvOs2NNXxk9kajSmyulhq7UC6ulaLC2dV1q M3dZf+oDyq1mXqLxJPu9wkfQyUxgfBvouPm5sBF8zgot4gW9Sic0QEOgrCB03FP5OamP 2RwMvCzpNOTEty53RTHmm3jk5BH2QWqyBqU/rSRCLYvAah5f9xqde6ye8qcBymscVn3C IBcQ==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=3g11L3dhad2k/v0WBXWSf2PoBpohQ9eEdqUzP6QB2AM=; b=lhhneFyk7xKEwXW8aWTXcN66BEWUJEzLXlCcz3Uywf+mPzIe7JVrUtXxOVuULrTIhl aY+9JEvkCQVtdIVlyYn+1iK+ijSdp0vWMpwZacfYFvVH8sarWjCFVdf6bCOzgQBuBJG3 RerObR8Irwdg5+QMk5AlU1RL6nay0bodoa9OlSok8G/ympMaDFCxV97nH4RAVyLAC0vJ gf2cGIJ0MZGGeoY7dyQGtE8eEHdInK0v0oTGO/jiO24da2vZDiPMQwdsOp7b+tjX+6AE yHTD/RcPEdP7gADLbI4unnH/BAbzROvzsxWwpLHHaK4R8NMcw+UChSNs595+2A+D7d3s uCvg==
X-Gm-Message-State: AOUpUlHFyfJu1PTF6aIs8zQMtKJoRDoF3Vjqg9cMoJzB6Iz64tULgo0M 9xnwGWyrd3xWcBSzMwDsqcO4/5JM
X-Google-Smtp-Source: AAOMgpeRRBSXGsezTf6nyVRekh84rzqqz0oHi9IFA7w/xRMAGQA159Qntt2d+0BFkWhc0q2g4Y0xAw==
X-Received: by 2002:a65:5205:: with SMTP id o5-v6mr18700543pgp.108.1532488372760; Tue, 24 Jul 2018 20:12:52 -0700 (PDT)
Received: from [192.168.178.40] ([118.148.121.80]) by smtp.gmail.com with ESMTPSA id s20-v6sm15971724pga.37.2018.07.24.20.12.49 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 24 Jul 2018 20:12:51 -0700 (PDT)
To: Tom Herbert <tom@herbertland.com>, "Templin (US), Fred L" <Fred.L.Templin@boeing.com>
Cc: "internet-area@ietf.org" <int-area@ietf.org>, "intarea-chairs@ietf.org" <intarea-chairs@ietf.org>
References: <F227637E-B12D-45AA-AD69-74C947409012@ericsson.com> <e794c5ddbb814c0384c8dd06eb6acf7c@XCH15-06-08.nw.nos.boeing.com> <CALx6S354kjyNaMYDo-XgsuiijapONC4GH+ozH8AXw-tQr0Ci=A@mail.gmail.com>
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Message-ID: <cce6f77d-9550-78d0-b472-120970b6668e@gmail.com>
Date: Wed, 25 Jul 2018 15:12:51 +1200
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1
MIME-Version: 1.0
In-Reply-To: <CALx6S354kjyNaMYDo-XgsuiijapONC4GH+ozH8AXw-tQr0Ci=A@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: quoted-printable
Archived-At: <https://mailarchive.ietf.org/arch/msg/int-area/b89gK5UptaxTluv9J-O_phEN1S8>
Subject: Re: [Int-area] WG Adoption Call: IP Fragmentation Considered Fragile
X-BeenThere: int-area@ietf.org
X-Mailman-Version: 2.1.27
Precedence: list
List-Id: IETF Internet Area Mailing List <int-area.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/int-area>, <mailto:int-area-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/int-area/>
List-Post: <mailto:int-area@ietf.org>
List-Help: <mailto:int-area-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/int-area>, <mailto:int-area-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 25 Jul 2018 03:13:04 -0000

On 25/07/2018 11:46, Tom Herbert wrote:
> On Tue, Jul 24, 2018 at 3:54 PM, Templin (US), Fred L
> <Fred.L.Templin@boeing.com> wrote:
>> I have an observation that I would like to see addressed in the document. Some applications
>> (e.g., 'iperf3' and others) actually leverage IP fragmentation to achieve higher data rates than
>> are possible using smaller (but unfragmented) whole packets.
>>
>> Try it - by default, iperf3 sets an 8KB UDP packet size and allows packets to fragment across
>> paths that support only smaller MTUs. I have seen iperf3 exercise IP reassembly at line rates
>> on high-speed links, i.e., it shows that reassembly at high rates is feasible.
>>
>> We know from RFC4963 that there are dangers for reassembly at high rates, but there are
>> applications such as iperf3 that ignore the "SHOULD NOT" and leverage IP fragmentation
>> anyway. So, should the "SHOULD NOT" have an asterisk?
>>
> Fred,
> 
> My reading of the draft is that IP fragmentation is fragile on the
> open Internet and should be avoided for applications that run over the
> Internet. That doesn't mean that fragmentation should be avoided in
> all use cases. In particular, if fragmentation is used in a closed
> network with low loss and has appropriate security measures in place,
> then it can be beneficial. I suspect that describes the network that
> your're running iperf in. If this interpretation of the draft's intent
> is correct, maybe there could be some words to clarify that.

Those words are in RFC2119 already:

>> 4. SHOULD NOT   This phrase, or the phrase "NOT RECOMMENDED" mean that
>>    there may exist valid reasons in particular circumstances when the
>>    particular behavior is acceptable or even useful, but the full
>>    implications should be understood and the case carefully weighed
>>    before implementing any behavior described with this label.
   Brian

> Tom
> 
>> Thanks - Fred
>>
>>> -----Original Message-----
>>> From: Int-area [mailto:int-area-bounces@ietf.org] On Behalf Of Wassim Haddad
>>> Sent: Tuesday, July 24, 2018 12:43 PM
>>> To: internet-area@ietf.org <int-area@ietf.org>
>>> Cc: intarea-chairs@ietf.org
>>> Subject: [Int-area] WG Adoption Call: IP Fragmentation Considered Fragile
>>>
>>> Dear all,
>>>
>>> We would like to start a WG adoption call for draft-bonica-intarea-frag-fragile (“IP Fragmentation Considered Fragile”).
>>>
>>> https://www.ietf.org/id/draft-bonica-intarea-frag-fragile-03.txt
>>>
>>>
>>> Please indicate your preferences on the mailling list. The deadline is August 10th.
>>>
>>>
>>> Thanks,
>>>
>>> Juan & Wassim
>>> _______________________________________________
>>> Int-area mailing list
>>> Int-area@ietf.org
>>> https://www.ietf.org/mailman/listinfo/int-area
>> _______________________________________________
>> Int-area mailing list
>> Int-area@ietf.org
>> https://www.ietf.org/mailman/listinfo/int-area
> 
> _______________________________________________
> Int-area mailing list
> Int-area@ietf.org
> https://www.ietf.org/mailman/listinfo/int-area
>