[ih] IPv8...

[Dave Crocker]

> I don't recall anyone explicitly saying "no flag day" but I do recall a
> strong sentiment that we need a glide path rather than simply flipping a
> switch and that reflected what we'd seen in the prior dozen or so years.


For a very long time, I've seen 'No flag day' as a core design 
constraint for any effort to evolve an existing service, and have heard 
it cited in many conversations over the years.  But, really, the lesson 
is frequently stronger than that, IMO:

Old protocols never die and they don't fade away.  Contrary to wishful 
thinking.  The power of an installed base, at Internet scale, is not to 
be trifled with.

By way of offering an obscure example of this reality, take a look at 
the 'obsolete' construct in 
https://www.rfc-editor.org/rfc/rfc2822#page-29. Note that it has been 
retained in later revisions.  Because usage of those components persists.

Long ago, Vint offered the view that the Internet has one lesson:  
scaling.  While that lesson is learned and respected for design work 
involving performance and reliability, it has frequently been ignored 
with respect to the power of installed base.

d/

-- 
Dave Crocker

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