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

Brian E Carpenter <brian.e.carpenter@gmail.com> Fri, 27 July 2018 20:51 UTC

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To: Ole Troan <otroan@employees.org>
Cc: Fernando Gont <fernando@gont.com.ar>, Tom Herbert <tom@herbertland.com>, "internet-area@ietf.org" <int-area@ietf.org>, "intarea-chairs@ietf.org" <intarea-chairs@ietf.org>
References: <F227637E-B12D-45AA-AD69-74C947409012@ericsson.com> <0466770D-C8CA-49BB-AC10-5805CFDFB165@strayalpha.com> <8e5ba0b3-837e-02d1-d9d9-7c5e596c1774@gont.com.ar> <CALx6S34VMeLS7bqL4Zt0xZ+==5hUT7Q2=5m01a14mJ4B3J6G3g@mail.gmail.com> <50a1e177-6b37-b89a-2caf-5caf1cbc955b@gont.com.ar> <7e9260c4-462f-35bc-b962-cc85230058e2@gmail.com> <4D481FC7-BCE4-4F2D-AF16-7EF054D0AAA0@employees.org>
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
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Date: Sat, 28 Jul 2018 08:51:32 +1200
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Subject: Re: [Int-area] WG Adoption Call: IP Fragmentation Considered Fragile
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On 28/07/2018 08:28, Ole Troan wrote:
> 
> 
>> On 27 Jul 2018, at 22:12, Brian E Carpenter <brian.e.carpenter@gmail.com> wrote:
>>
>> Fragmentation, (PL)PMTUD, extension headers, and innovative
>> L4 protocols are very possibly not viable on the open Internet.
>> At least, we can't assume that they will work on arbitrary paths.
>> Sad but apparently true.
> 
> Hasn’t this been discussed ad infinitum in the ossification work?
> If you want to generalize, nothing is guaranteed to work across an arbitrary path in the Internet. 
> 
> So what? This is part of a tussle and it would be making a self fulfilling prophecy for us to take all policy based filtering or other brokenness into consideration when designing protocols. 

So you'd prefer that we design protocols that can't possibly work?

Yes, it's a tussle. But sometimes it's better to know you're in a
fight; it gives you a better chance of winning ;-). Anyway, we're
off topic, sorry, my fault.

   Brian