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

Fernando Gont <> Tue, 03 September 2019 20:49 UTC

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To: Tom Herbert <>, Bob Hinden <>
Cc: "Templin (US), Fred L" <>, "" <>, IESG <>, Joel Halpern <>, "" <>, "" <>
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Date: Tue, 3 Sep 2019 23:49:02 +0300
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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 3/9/19 23:33, Tom Herbert wrote:
> Bob,
> I agree with Fred. Note, the very first line of the introduction:
> "Operational experience [Kent] [Huston] [RFC7872] reveals that IP
> fragmentation introduces fragility to Internet communication".
> This attempts to frame fragmentation as being generally fragile with
> supporting references. However, there was much discussion on the list
> about operational experience that demonstrates fragmentation is not
> fragile.

Discussion is not measurements. Do you have measurements that suggest

We did separate measurements, with different methodologies, and they
suggest the same thing. You can discuss as much as you want. But that
will not make fragmentation work.

> In particular, we know that fragmentation with tunnels is
> productively deployed and has been for quite some time. So that is the
> counter argument to the general statement that fragmentation is
> fragile. With the text about tunneling included in the introduction I
> believe that was sufficient balance of the arguments, but without the
> text the reader could be led to believe that fragmentation is fragile
> for everyone all the time which is simply not true and would be
> misleading.

"fragile" means that it fails in an uncceptably large number of cases.
~30 failure rate is not acceptable. ~20% isn't, either.


> But the "problem" of fragmentation is in intermediate devices that
> don't properly handle it as the draft highlights. So it seems like
> part of addressing the problem should also be to fix the problem! That
> is implementations should be fixed to deal with fragmentation.

The same logic would solve the problem of widespread famine, and others.
I don't think that logic has solved any real problems in the real world.

Fernando Gont
SI6 Networks
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