Re: using "reserved" IPv6 space

[Stephen Sprunk <stephen () sprunk org>]

On 18-Jul-12 13:07, Saku Ytti wrote:
> On (2012-07-18 11:39 -0500), Stephen Sprunk wrote:
> > Those were not considered requirements for the algorithm in RFC 4193 since there is no scenario /where RFC 4193 
> > addresses are a valid solution in the first place/ for which testability or provability of the algorithm's results 
> > are important or even useful.
> If collision occurs, if dispute occurs, provability that one party did not use BCP method can be useful to solve 
> dispute and decide who renumbers.

In my experience, pointing at RFCs is rarely how disputes are resolved
in the real world.

> Other potential problem with RFC, if you have software to generate two, if software runs parallel, it may generate 
> same prefixes.

It is incredibly unlikely, and that is all RFC 4193 claims to offer:
/statistically /unique addresses.  If you want /provably/ unique
addresses, use GUAs--or lobby for ULA-C, which to date has been soundly
rejected for lack of usefulness.

> IEEE decided 2008 or 2009 to start allocation OUIs randomly, since some cheapskates were assigning themselves 'free' 
> OUIs from end of the space, confident it'll never collide. So duplicate OUIs can happen. Also some NIC vendors ship 
> with non-unique MAC.

You'd still need two systems with duplicate MACs to run the algorithm at
exactly the same timestamp, which IIRC has a resolution of 2^-32 seconds.

> What makes RFC method good?

RFC 4193 doesn't mandate any particular algorithm; it just provides an
example that was designed to be easily implemented and used.  You can
use another RNG if you wish.

S

-- 
Stephen Sprunk         "God does not play dice."  --Albert Einstein
CCIE #3723         "God is an inveterate gambler, and He throws the
K5SSS        dice at every possible opportunity." --Stephen Hawking

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