Re: [tsvwg] Protocol ossification in draft-ietf-tsvwg-transport-encrypt-07.txt

Colin Perkins <csp@csperkins.org> Tue, 09 July 2019 22:35 UTC

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From: Colin Perkins <csp@csperkins.org>
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Date: Tue, 9 Jul 2019 23:35:38 +0100
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Cc: Tom Herbert <tom@herbertland.com>, tsvwg <tsvwg@ietf.org>
To: Joe Touch <touch@strayalpha.com>
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Subject: Re: [tsvwg] Protocol ossification in draft-ietf-tsvwg-transport-encrypt-07.txt
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> On 9 Jul 2019, at 05:35, Joe Touch <touch@strayalpha.com>; wrote:
>> On Jul 8, 2019, at 8:05 AM, Tom Herbert <tom@herbertland.com <mailto:tom@herbertland.com>> wrote:
>> 
>> "A reliance on the presence and semantics of specific header
>> information  leads to ossification…"
> 
> 
> Relying on the semantics of a protocol header is also called a standard. 
> 
>> “...In some case this could be benign or advantageous to
>> the protocol”
> 
>> I am dubious about any statement that protocol ossification of
>> transport layer by middleboxes is a good thing.
> 
> 
> Ossification and stability are two sides of exactly the same coin.
> 
> It’s called ossification when the variation of a standard is no longer supported, e.g., because of middleboxes assumptions beyond that defined by the standard.
> 
> It’s called stability when we can rely on a set of definitions that constrain arbitrary variation in controlled ways.

Exactly. 

We might choose to declare certain properties of a protocol as invariant, because we want a stable substrate on which others can build, including middlebox vendors. That is, we might choose to intentionally accept and encourage ossification, because we believe the benefits of stability for those features outweigh the benefits of flexibility. 

The problem is not ossification as such. It’s ossification of things that we intended to be changeable. 


-- 
Colin Perkins
https://csperkins.org/