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

Tom Herbert <tom@herbertland.com> Fri, 27 July 2018 15:15 UTC

Return-Path: <tom@herbertland.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 F2DCF130EBD for <int-area@ietfa.amsl.com>; Fri, 27 Jul 2018 08:15:42 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.91
X-Spam-Level:
X-Spam-Status: No, score=-1.91 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, T_DKIMWL_WL_MED=-0.01] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=herbertland-com.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 UiVBA6bpPnMh for <int-area@ietfa.amsl.com>; Fri, 27 Jul 2018 08:15:40 -0700 (PDT)
Received: from mail-qt0-x235.google.com (mail-qt0-x235.google.com [IPv6:2607:f8b0:400d:c0d::235]) (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 AD31C129C6A for <int-area@ietf.org>; Fri, 27 Jul 2018 08:15:40 -0700 (PDT)
Received: by mail-qt0-x235.google.com with SMTP id y19-v6so5379335qto.5 for <int-area@ietf.org>; Fri, 27 Jul 2018 08:15:40 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=herbertland-com.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=X8BBd+ZiyGHAH2GVJxfBo4Ov4LYEH1JHhtL9trY4imY=; b=1X7QCLfWZ7RCzpr3cudRox1ZTDH9+APyZD9tvNdm1OUeHBABOkMl3Bd/tbxdNxcjX0 o3DCNlNTZh7ZrbJiIEIJHMlLsPNZF+Dt9eyYSEaO98fWwPs59NTYFg9h/MeJd1AVghBu iFF/PrdF3lImYKkosf2Bklzcl2z9Em3IC+dkRo1dPXKOprSik72M2BafpD/jhhvqsor6 7jkPaxLpy267ZB8uMMKZyjXM7UKsc8hqfN+wcJXml2Z2UMbSwGVqGigK9XtWCZSWWzNt 3eKixduUVQYOeXhsKStZw/IJSDFZVmKIfptoVdWO45okAm4zwTvfIgS6aIe09HlsVraB WdaQ==
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:content-transfer-encoding; bh=X8BBd+ZiyGHAH2GVJxfBo4Ov4LYEH1JHhtL9trY4imY=; b=tHPO8sMKVZc/dc/vOazk90OZW2zamduGpLURLUAfVTE5XihVzbMQejYGv9RKuXHHSF 3F6rtc0wkUML3ZfZAyQrkmGk9nm5WOqSrEZjv1oefjtxNOV8N+yov0ART592WSKxDEwD p/QTmisehFUZm/oTqGZMDqnCEPj0mizudLlFp6a6K2pUgCeTbypc6Vg9xP/xIagge2Uy XVStQzo1l8rzoVtDSwUrqkhqs74Y1Dv6zVwdZzUO4K4p0kgHugP1DAuBvvj5aT6vFsU5 +kSEJalMph4W3Cdv2GDCv2Z4m8H1sPgBGM4D37WK3Ev4RjyJIbWJn7sYX3J95h2X/0Zm RnYw==
X-Gm-Message-State: AOUpUlFuDJV31CCCGlTCPM1TVX4YXMCt0F7KzYATzcePZIYhHUyy3hRr KoO1f0NbANxiW+R1t4KbD4APvm60E0yUaShGJ0vY5A==
X-Google-Smtp-Source: AAOMgpd73ELdKQNy9+V/y+Zu0E39sz8OEmly7N2Jt+Z/aEI5RFoxlPDE8j6eJsynF8+9DSBsg4f6uHL90dGmRoSayUM=
X-Received: by 2002:a0c:886d:: with SMTP id 42-v6mr6089260qvm.242.1532704539682; Fri, 27 Jul 2018 08:15:39 -0700 (PDT)
MIME-Version: 1.0
Received: by 2002:ac8:3304:0:0:0:0:0 with HTTP; Fri, 27 Jul 2018 08:15:39 -0700 (PDT)
In-Reply-To: <8e5ba0b3-837e-02d1-d9d9-7c5e596c1774@gont.com.ar>
References: <F227637E-B12D-45AA-AD69-74C947409012@ericsson.com> <0466770D-C8CA-49BB-AC10-5805CFDFB165@strayalpha.com> <8e5ba0b3-837e-02d1-d9d9-7c5e596c1774@gont.com.ar>
From: Tom Herbert <tom@herbertland.com>
Date: Fri, 27 Jul 2018 08:15:39 -0700
Message-ID: <CALx6S34VMeLS7bqL4Zt0xZ+==5hUT7Q2=5m01a14mJ4B3J6G3g@mail.gmail.com>
To: Fernando Gont <fernando@gont.com.ar>
Cc: Joe Touch <touch@strayalpha.com>, Wassim Haddad <wassim.haddad@ericsson.com>, "internet-area@ietf.org" <int-area@ietf.org>, "intarea-chairs@ietf.org" <intarea-chairs@ietf.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Archived-At: <https://mailarchive.ietf.org/arch/msg/int-area/v5JwGB9s4RKdDlspl-l6aq5c79o>
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: Fri, 27 Jul 2018 15:15:43 -0000

On Fri, Jul 27, 2018 at 5:38 AM, Fernando Gont <fernando@gont.com.ar> wrote:
> Hi, Joe,
>
> On 07/26/2018 04:14 AM, Joe Touch wrote:
>> Hi, all,
>>
>> I still think it would be useful for this doc to describe how tunnels interact with fragmentation (per draft-ietf-intarea-tunnels), which seems to be something I’ve noted several times before.
>>
>> I’m also still not thrilled with the title I’d be happier with “IP fragmentation still not supported per requirements”, and I’d have to see where this goes with final recommendations.
>>
>> But I agree *some* statement is worthwhile here. My primary concern is that if we’re not careful, endorsing the status quo will only ensure nothing changes.
>
> FWIW, I see and understand your point. However, based on the operational
> implications of fragmentation, it believe it is *extremely* unlikely
> that the situation improves (if at all possible).
>
> So my take is that this I-D rather than endorsing the status quo, is
> essentially warning possible users of what it may happen with their
> fragmented traffic.
>
> Side coments:
>
> It would all seem that there are two operating environments:
> * Controlled environments, where you can somehow make all this work
> * Public internet, which is more of a "fingers crossed" thing (if anything).
>
> I'm not saying that I'm happy with the outcome, but rather that I think
> that from an engenering point of view, it all looks like this ship has
> sailed, and we should probably figure out how to deal with those cases
> where fragmentation is actually needed.
>
Fernado,

Couldn't that same line of thinking be applied to several other
protocol features? So has the ship sailed for out ability to ever use
extension headers or any protocol other than TCP (and sometimes UDP)?
Maybe documents that recommend operational workarounds should
distinguish problems that inherent in the protocol from those that
have arisen because of non-conformant implementation. It's true that
calling implementations that probably won't help to fix what is out
there, but maybe this could help prevent new instances of
non-conformance.

Tom

> Thanks!
>
> Cheers,
> --
> Fernando Gont
> e-mail: fernando@gont.com.ar || fgont@si6networks.com
> PGP Fingerprint: 7809 84F5 322E 45C7 F1C9 3945 96EE A9EF D076 FFF1
>
>
>
> _______________________________________________
> Int-area mailing list
> Int-area@ietf.org
> https://www.ietf.org/mailman/listinfo/int-area