Re: [tcpm] Thoughts on EXP vs. PS in TCPM

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

Hi Michael!

Good questions.  Thanks for starting the thread.

I agree that TCPM is basically too conservative.  We have been too
conservative for a long time.  I probably contributed my fair share
to that.  But, I'd put a finer point on it: Have we ever issued
something at EXP (or PS for that matter!) that had to be pulled back
because it was too aggressive?  I am not conjuring anything at the
moment.

TCPM has long used EXP as a crutch.  We don't have the guts to label
something a PS, yet we still want to publish it.  And, no amount of
non-answers to "what's the experiment?" garners rough consensus for
issuing as PS.

And, my take is that the world doesn't much buy there to be a
distinction.  I.e., EXP doesn't dissuade general use of something.
And, I bet at least part of this is that we're just too conservative
with both kinds of RFCs.  If we occasionally did publish an EXP that
caused TCP to fall on its face then maybe people would be a bit more
careful.

That said, it's sort of hard to come up with good rules for
delineating.  For instance, consider this ...

> In order to start a WGLC in TCPM for EXP status, there SHOULD be
> one implementation in the main source code tree of an important
> TCP/IP stack; a default to "off" is perfectly
> acceptable.

Well, there are a number of implementations of IW=15 or IW=100, it's
just that these are off by default.  I.e., something like the
initial window is just a constant somewhere so what does it mean
that we have 'one implementation' of something like this?

I think in the end TCPM standardizes a wide variety of stuff and a
one-size rule may not apply.  E.g.,

  - We standardize actual protocol mechanisms (a la TFO) and those
    need some sort of interoperability kinds of criteria.

  - We standardize algorithms and those need some sort of behavioral
    and safety criteria (a la RACK).

  - We standardize constants and those need safety criteria (a la
    IW or RTO).

Further, my observation is that for the latter two in particular the
WG cares about 'one impl' vs. 'two impls' much less than we care
about the overall evidence that something works---or, where it falls
down.

I wish I had some idea about how to synthesize this better than
'perhaps we should relax and be less conservative', but I don't.
I'll think on it.

allman


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