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

Joe Touch <touch@strayalpha.com> Sun, 26 August 2018 22:37 UTC

Return-Path: <touch@strayalpha.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 47322130E03; Sun, 26 Aug 2018 15:37:29 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.989
X-Spam-Level:
X-Spam-Status: No, score=-1.989 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, T_SPF_PERMERROR=0.01] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=strayalpha.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 2kCeZ623VVTS; Sun, 26 Aug 2018 15:37:27 -0700 (PDT)
Received: from server217-3.web-hosting.com (server217-3.web-hosting.com [198.54.115.226]) (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 C6012130E17; Sun, 26 Aug 2018 15:37:27 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=strayalpha.com; s=default; h=To:References:Message-Id:Cc:Date:In-Reply-To: From:Subject:Mime-Version:Content-Type:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=0hf/R7+rtWTuubIdIDnqylXAZTgOqWY+L3fEJZSrP+0=; b=jFg2unMyELvfS0yvbYipbNZGU lGsixKjtX6WimsFrB7nUdEpTmcSqwOBvvt8XWpQjx7UBTu+TUIHejDktkW1o8v8Ec20aE1nLOAJQT BDHDlN9KpcWRDhSmmXXiKXgfQdMUEk5bn384iff0qJUp236ANOalU4pVRMGwg6CBORrtibk5bWPrg 440dc0yhTMyPrgqNzzaVNJd3T240iTbM9DXM3V25/k6dmlVraHGccvK86KxlpiufaPy/x2+GCEMXc QioN+31s2h90i2PE9ADYLY3Edpjriahu3K0tl0CXZwvfYcfgDI9+vBtTV08mUXJLi+rT3LyqYwJPr UeQyAO7rg==;
Received: from cpe-172-250-240-132.socal.res.rr.com ([172.250.240.132]:60837 helo=[192.168.1.77]) by server217.web-hosting.com with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91) (envelope-from <touch@strayalpha.com>) id 1fu3eu-002WXm-Gb; Sun, 26 Aug 2018 18:37:25 -0400
Content-Type: multipart/alternative; boundary="Apple-Mail=_C7DDD36C-1BD9-44E3-8CCA-9CE4D8A5CD43"
Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\))
From: Joe Touch <touch@strayalpha.com>
In-Reply-To: <20180826212702.pxkhrogoqo2wv7gr@faui48f.informatik.uni-erlangen.de>
Date: Sun, 26 Aug 2018 15:37:21 -0700
Cc: Mikael Abrahamsson <swmike@swm.pp.se>, int-area <int-area@ietf.org>, intarea-chairs@ietf.org
Message-Id: <8EEAB8D0-5E22-4BCF-915A-44C2BB3FC310@strayalpha.com>
References: <CALx6S34qmKngi3hK_PVrJA1DMa5kfaLww3jfqRKN=up5v0Y0Ww@mail.gmail.com> <8D23C8B1-C2DA-4A8B-A2BE-8CCF6233B3A5@strayalpha.com> <D1D5EDCE-7C43-4CD8-947C-AA43CDB18892@employees.org> <1B04E207-08FA-400F-BBED-67379FEFD64E@strayalpha.com> <137751A3-7C52-4CCF-AE9C-B99C4A85EFC1@strayalpha.com> <alpine.DEB.2.20.1808021749020.19688@uplift.swm.pp.se> <CALx6S35kw2dodgG2L3LE3A5y8RYEXy6izQWgrQTwg7-yPqpzOg@mail.gmail.com> <alpine.DEB.2.20.1808030857370.19688@uplift.swm.pp.se> <20180825032457.ol5rlrr7h2kqi6px@faui48f.informatik.uni-erlangen.de> <alpine.DEB.2.20.1808250827360.23215@uplift.swm.pp.se> <20180826212702.pxkhrogoqo2wv7gr@faui48f.informatik.uni-erlangen.de>
To: Toerless Eckert <tte@cs.fau.de>
X-Mailer: Apple Mail (2.3445.9.1)
X-OutGoing-Spam-Status: No, score=-1.0
X-AntiAbuse: This header was added to track abuse, please include it with any abuse report
X-AntiAbuse: Primary Hostname - server217.web-hosting.com
X-AntiAbuse: Original Domain - ietf.org
X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12]
X-AntiAbuse: Sender Address Domain - strayalpha.com
X-Get-Message-Sender-Via: server217.web-hosting.com: authenticated_id: touch@strayalpha.com
X-Authenticated-Sender: server217.web-hosting.com: touch@strayalpha.com
X-Source:
X-Source-Args:
X-Source-Dir:
X-From-Rewrite: unmodified, already matched
Archived-At: <https://mailarchive.ietf.org/arch/msg/int-area/HSEQmyHO4T5P_h8K6E5ZwKqkQuM>
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: Sun, 26 Aug 2018 22:37:29 -0000


> On Aug 26, 2018, at 2:27 PM, Toerless Eckert <tte@cs.fau.de> wrote:
> 
> Took us decades to figure out that in-network
> fragmentation (as mandaory in IPv4) is not a good thing, and
> we eliminated it for IPv6. Why do we hang on to fragmentation 
> from the host when tranport layers would be better doing it than the IP
> layer ?

See draft-ietf-intarea-tunnels

As I’ve noted repeatedly, any layer for which there is a maximum size ultimately needs a way to fragment and reassemble at that layer, otherwise it ceases to be a complete participant in the network stack (i.e., if fragmentation/reaseembly happens at another layer, then that layer is effectively shut out of being the basis of a tunnel or protocol layer without that other layer.

For IP, the simple issue is that the requirement for IP over IP (for IPsec tunnels, at a minimum), requires it.

Joe