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

Tom Herbert <tom@herbertland.com> Tue, 03 September 2019 15:39 UTC

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From: Tom Herbert <tom@herbertland.com>
Date: Tue, 3 Sep 2019 08:39:11 -0700
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To: Fernando Gont <fgont@si6networks.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>
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Subject: Re: [Int-area] Alissa Cooper's No Objection on draft-ietf-intarea-frag-fragile-16: (with COMMENT)
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On Tue, Sep 3, 2019, 8:31 AM Fernando Gont <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. 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.

I don't understand this change nor the others in the latest draft either.

Tom


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> SI6 Networks
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