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[tsvwg] Options larger than 255 (was RE: draft-ietf-udp-options issues from IETF 104)

<mohamed.boucadair@orange.com> Thu, 18 July 2019 11:48 UTC

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From: mohamed.boucadair@orange.com
To: "gorry@erg.abdn.ac.uk" <gorry@erg.abdn.ac.uk>
CC: tsvwg <tsvwg@ietf.org>
Thread-Topic: Options larger than 255 (was RE: [tsvwg] draft-ietf-udp-options issues from IETF 104)
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Date: Thu, 18 Jul 2019 11:48:24 +0000
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Subject: [tsvwg] Options larger than 255 (was RE: draft-ietf-udp-options issues from IETF 104)
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Re-,

Associating a meaning with Len=0 as proposed by Joe may not be intuitive. An alternate approach would be: 

* 'Len' only covers the option data field (that is, 'kind' and 'Len' fields are not covered. The overall option length can be easily inferred).
* Associate a meaning with one of the two values we grabbed: 
 - 254 or 255: a 16-bit extended length field follows   

Cheers,
Med

> -----Message d'origine-----
> De : tsvwg [mailto:tsvwg-bounces@ietf.org] De la part de Gorry Fairhurst
> Envoyé : jeudi 18 juillet 2019 12:22
> À : gorry@erg.abdn.ac.uk
> Cc : tsvwg
> Objet : Re: [tsvwg] draft-ietf-udp-options issues from IETF 104
> 
> >
> > Gorry
> P.S. I like the idea to explicitly allow options longer than 255 bytes?
> - This seems useful for fragmentation and would be an easy addition,
> someone suggested using 0 option length to indicate a 16b length field,
> which could make total sense. As in:
> 
> https://mailarchive.ietf.org/arch/msg/tsvwg/B4oeZkpagdl4gkAMDCFW7F1A7_8
> 
> Gorry

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