Re: [Int-area] Alissa Cooper's No Objection on draft-ietf-intarea-frag-fragile-16: (with COMMENT)

Fernando Gont <fgont@si6networks.com> Tue, 03 September 2019 15:57 UTC

Return-Path: <fgont@si6networks.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 A0D601208FB; Tue, 3 Sep 2019 08:57:35 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.899
X-Spam-Level:
X-Spam-Status: No, score=-1.899 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
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 Y2SQlmIkX5xK; Tue, 3 Sep 2019 08:57:32 -0700 (PDT)
Received: from fgont.go6lab.si (fgont.go6lab.si [IPv6:2001:67c:27e4::14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 9CF29120903; Tue, 3 Sep 2019 08:57:32 -0700 (PDT)
Received: from [192.168.1.14] (ppp-94-69-228-25.home.otenet.gr [94.69.228.25]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by fgont.go6lab.si (Postfix) with ESMTPSA id C80A186090; Tue, 3 Sep 2019 17:57:29 +0200 (CEST)
To: Tom Herbert <tom@herbertland.com>
Cc: "Templin, Fred L" <Fred.L.Templin@boeing.com>, Joe Touch <touch@strayalpha.com>, Alissa Cooper <alissa@cooperw.in>, Joel Halpern <joel.halpern@ericsson.com>, "draft-ietf-intarea-frag-fragile@ietf.org" <draft-ietf-intarea-frag-fragile@ietf.org>, "int-area@ietf.org" <int-area@ietf.org>, The IESG <iesg@ietf.org>, "intarea-chairs@ietf.org" <intarea-chairs@ietf.org>
References: <156751558566.9632.10416223948753711891.idtracker@ietfa.amsl.com> <B7C5DF29-92B2-477B-9C30-F47E338038EE@strayalpha.com> <efabc7c9f72c4cd9a31f56de24669640@boeing.com> <bc1c4352-ad40-4b89-5178-c55f4f2ba115@si6networks.com> <CALx6S36vkT+gzCz9cTfzyVZV8V4+pHCKtk1XX3umu6rQN6OV-g@mail.gmail.com>
From: Fernando Gont <fgont@si6networks.com>
Openpgp: preference=signencrypt
Message-ID: <7f516385-5723-9238-d0ca-2b18b2fba9de@si6networks.com>
Date: Tue, 3 Sep 2019 18:53:54 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0
MIME-Version: 1.0
In-Reply-To: <CALx6S36vkT+gzCz9cTfzyVZV8V4+pHCKtk1XX3umu6rQN6OV-g@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Archived-At: <https://mailarchive.ietf.org/arch/msg/int-area/TZnD1U5jQe37VV2oPOj_P6LljHY>
Subject: Re: [Int-area] Alissa Cooper's No Objection on draft-ietf-intarea-frag-fragile-16: (with COMMENT)
X-BeenThere: int-area@ietf.org
X-Mailman-Version: 2.1.29
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: Tue, 03 Sep 2019 15:57:41 -0000

On 3/9/19 18:39, Tom Herbert wrote:
> 
> 
> On Tue, Sep 3, 2019, 8:31 AM Fernando Gont <fgont@si6networks.com
> <mailto:fgont@si6networks.com>> wrote:
> 
>     On 3/9/19 17:33, Templin (US), Fred L wrote:
>     > Why was this section taken out:
>     > 
>     >> 1.1.  IP-in-IP Tunnels
>     >>     
>     >>    This document acknowledges that in some cases, packets must
>     be     
>     >>    fragmented within IP-in-IP tunnels
>     [I-D.ietf-intarea-tunnels].     
>     >>    Therefore, this document makes no additional recommendations     
>     >>    regarding IP-in-IP tunnels.
>     >
>     > Tunnels always inflate the size of packets to the point that they
>     may exceed
>     > the path MTU even if the original packet is no larger than the
>     path MTU. And,
>     > for IPv6 the only guarantee is 1280. Therefore, in order to
>     robustly support
>     > the minimum IPv6 MTU tunnels MUST employ fragmentation.
> 
>     Isn't that an oxymoron? If fragmentation is fragile, if you need
>     something robust, you need to rely on something else....
> 
> 
> Not really, to say fragmentation is fragile is a subjective statement,
> not a quantifiable fact.

RFC7872. IIRC, Geoff did his own independent measurements.



> As discussed on the list, fragmentation is
> productively in use in many networks that employ tunneling. In those
> cases fragmentation is not fragile and so there's nothing to fix.

The measurements I've seen about fragmentation on the big-I internet
seem to indicate that it is fragile. Yes, you can always build your own
private network where it is not.


-- 
Fernando Gont
SI6 Networks
e-mail: fgont@si6networks.com
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492