"Registered ULA" (Was: using ULA for 'hidden' v6 devices?)

Jeroen Massar jeroen at unfix.org
Wed Jan 25 18:08:10 UTC 2012

On 2012-01-25 18:55 , Justin M. Streiner wrote:
>> Locally managed means locally manage, though.  The RFC is more of
>> a suggestion than a requirement at that point.
> Right, though it's a shame that the registry-assigned ULA concept didn't
> take off.

What everybody calls "Registered ULA" or ULA-C(entral) is what the RIRs
already provide. Also entities that have such a strict requirement are
perfectly served with address space the RIRs provide.

And from my POV unless one is deploying devices which set up ad-hoc
networks, there is no real reason to use ULA at all. Just take a chunk
from your RIR assigned space, firewall it off, or simply do not route it
and presto, you got a globally registered unique block of address space.

>From that POV the only reason one might not want RIR space is that one
has to pay a wee bit of money for the RIR space, guess what, any kind of
ULA-C space with guarantees for being global unique will have that same

But if you want to stick to ULA anyway and you want a bit more certainty
that your ULA prefix does not clash, you can generate a random one as
per the RFC and register it:


As long as everybody looks at that list, one will be clash free.

And yes, ULA comes in chunks of /48 if you need more than that you can
just register multiple disjunct ones or... what about that RIR space?
Likely one site or another will start using that thing called the
Internet anyway at one point.


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