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

Owen DeLong owen at delong.com
Wed May 16 11:24:42 EDT 2012

On May 16, 2012, at 8:11 AM, Michael Richardson wrote:

> Hash: SHA1
>>>>>> "Owen" == Owen DeLong <owen at delong.com> writes:
>>> 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 well.
>    Owen> So what... He said he wanted equivalent functionality to
>    Owen> RFC-1918 where your risk of collision is more like 1 in 3 at
>    Owen> best and usually 1 in 1 in my experience.
> RFC1918 risk of collision is the reason to argue for IPv6 in the first
> place.  I work for one company that decided that squatting on
> for their chassis communications was better than conflicting with RFC1918.

No, RFC-1918 and NAT are among the key reasons to argue for IPv6.
Collision is just icing on the cake.

> But, I didn't say it was risk of collision with ULA-R that was the
> main problem, it is lack of reverse DNS and lack of whois that is the
> problem.   

Why do you need non-local RDNS and/or WHOIS for local-only addresses?

If the addresses should not be seen outside of your organization, why would you need a directory service to tell you who the addresses belong to?

If the only people that should be seeing (and thus looking up) the addresses in RDNS, then, so long as all of the resolvers in your organization know about your authoritative server for that applicable ip6.arpa zone file, then, you have RDNS.

So I don't see those as real problems for proper use of ULA.


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