Re: [tsvwg] DPLPMTU (was RE: design assumptions - draft-ietf-udp-options - trying to see the bigger picture)

Gorry Fairhurst <gorry@erg.abdn.ac.uk> Fri, 19 July 2019 08:13 UTC

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To: mohamed.boucadair@orange.com, "C. M. Heard" <heard@pobox.com>
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From: Gorry Fairhurst <gorry@erg.abdn.ac.uk>
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Date: Fri, 19 Jul 2019 09:13:02 +0100
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Subject: Re: [tsvwg] DPLPMTU (was RE: design assumptions - draft-ietf-udp-options - trying to see the bigger picture)
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Thanks: We do need to check that,

Gorry

On 19/07/2019 06:32, mohamed.boucadair@orange.com wrote:
> Hi Mike, Gorry, all,
>
> (Focusing on the DPLPMTU part)
>
> How the pieces are structured/described in the two documents is broken.
>
> udp-options has a normative dependency on DPLPMTU I-D to specify how this would work, but that document does not elaborate on the processing of UDP options.
>
> Cheers,
> Med
>
>> -----Message d'origine-----
>> De : tsvwg [mailto:tsvwg-bounces@ietf.org] De la part de Gorry Fairhurst
>> Envoyé : jeudi 18 juillet 2019 18:16
>> À : C. M. Heard
>> Cc : TSVWG
>> Objet : Re: [tsvwg] design assumptions - draft-ietf-udp-options - trying
>> to see the bigger picture
>>
>> On 18/07/2019, 16:46, C. M. Heard wrote:
>>> On Thu, Jul 18, 2019 at 3:39 AM Gorry Fairhurst wrote:
>>>> For DPLPMTU (#6) the complexity is in another spec (which seems
>> correct
>>>> to me). I'd be interested whether a separate spec of Frag is also one
>>>> way to ensure we get experience with the core spec, and then consider
>>>> how to design Frag (#5, #8).
>>> For DPLPMTU the complexity is in another spec, but the tools that UDP
>>> options provide for it are in the base spec. Those tools are:
>>>
>>> - padding for probe packets
>>> - request option
>>> - response option
>>>
>>> The request and response options are pretty straightforward, but the
>>> details of how padding will be accommodated may well depend on what
>>> packet format we converge to for providing other things, especially
>>> FRAG.
>> DPLPMTUD works best with *just* padding packets (i.e. that carry no
>> payloads or fragments). It's just so much easier to run the algorithm.