Re: [tsvwg] I-D Action: draft-ietf-tsvwg-udp-options-22.txt

["[e-mail]" <[e-mail]>]

….
> On Jun 10, 2023, at 10:41 AM, Tom Herbert <tom=[e-mail]> wrote:
> 
> On Sat, Jun 10, 2023 at 10:10 AM [e-mail]
> <[e-mail]> wrote:
>> 
>> 
>> On Jun 10, 2023, at 8:40 AM, Tom Herbert <[e-mail]> wrote:
>> 
>> On Fri, Jun 9, 2023 at 8:30 PM [e-mail]
>> <[e-mail]> wrote:
>> ...
>> By expecting implementations that do more to allow more, the current wording both avoids that lock-in and allows more modest implementations - e.g., that don’t have resources to enable 100 options - to not need to support packets with 100 options.
> 
> If different implementations are allowed to choose different protocol
> parameters then that reduces interoperability;

This isn’t a protocol parameter. Many protocols have different expectations for how widely each option is supported - see TCP, e.g.

>> ...
>> Adapted to the implementation. It does not talk about adaptive algorithms.
>> 
>> As above, this just indicates that lesser implementations can allow less, but full-featured ones need to accommodate more.
>> 
>> for a new protocol that hasn't yet seen any
>> deployment. So much simpler to just set a limit. So we can assume the
>> default limit will be locked in globally, and once systems are
>> deployed changing those limits takes years as legacy systems are
>> replaced.
>> 
>> 
>> How’s that working out for IPv6? (It doesn’t - once you set the bar low, that’s it).
> 
> You're asking the wrong question.The right question is "how did
> defining unlimited options work out for out for IPv6?”.

The right question is “how is treating every unexpected behavior as an attack working out”?

And it isn’t.

Further, IPv6 options involve intermediate nodes that need to invest resources. UDP options do not. 
(Which is why limited HBH options is appropriate, but limiting destination options is not).

> Conversely,
> one could ask "how did limited options work out for TCP?"

Well, then not so well:

See draft-ietf-tcpm-tcp-edo and the numerous attempts to extend an option space that isn’t sufficient now, but at the time “40 bytes” was a specific limitation.

See also MP-TCP and numerous methods to try to treat other portions of TCP segments as option space as well.

Joe