[arin-ppml] Encouraging IPv6 Transition (was: Clarify /29 assignment identification requirement)

William Herrin bill at herrin.us
Tue May 15 14:56:57 EDT 2012

On 5/15/12, Chris Grundemann <cgrundemann at gmail.com> wrote:
> On Tue, May 15, 2012 at 12:00 PM, Michael Richardson <mcr at sandelman.ca>
> wrote:
>> And I'll say it again: enterprises and equipment vendors need
>> Non-Connected Network space, and they need it at the same cost as
>> RFC1918 address space.
> It's RFC 4193 space (ULA) for IPv6:
> https://tools.ietf.org/html/rfc4193. Or am I missing something?

Hi Chris,

The math for statistical uniqueness in ULA, while internally correct,
is based on some suspect assumptions. If you replace them with
worst-case assumptions, the probability of collision when
interconnecting two large organizations increases to something on the
order of 1 in 1000. Maybe higher if you consider human factors as

ULA Central or a similar RIR-managed ULA space might provide a better
guarantee of uniqueness and would, for a certainty, make it easier to
figure out who's "in the wrong" and must renumber when a collision
occurs. It would also offer a user better control over what happens
during data leak scenarios, e.g. RDNS requests which incorrectly make
it to the Internet DNS servers.

On the flip side, ULA is at it's very worst still far better than RFC1918.

Bill Herrin

William D. Herrin ................ herrin at dirtside.com  bill at herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004

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