[ppml] 2005-1 status

Stephen Sprunk stephen at sprunk.org
Tue Feb 7 15:37:14 EST 2006

Thus spake <Michael.Dillon at btradianz.com>
>> Nor are we supposed to be doing our best to waste IPv6 space by
>> holding to an unstated "/48 per location" policy when a typical
>> location only needs one or two /64s.
> In fact you are wrong. According to RFC 3177
> http://www.rfc-editor.org/rfc/rfc3177.txt
> we are supposed to be giving a /48 unless we are absolutely
> certain that the site will never ever need more than one subnet.
> Therefore, if the site needs 2 subnets today, then they qualify
> for a /48 with no questions asked. In fact, if they might add a
> second subnet in the next 10 years, they also qualify for a
> /48 today.
> Here is a quote from RFC 3177:
> 4. Conservation of Address Space
>   The question naturally arises whether giving a /48 to every
>   subscriber represents a profligate waste of address space.  Objective
>   analysis shows that this is not the case.  A /48 prefix under the 001
>   Global Unicast Address prefix contains 45 variable bits.  That is,
>   the number of available prefixes is 2 to the power 45 or about 35
>   trillion (35,184,372,088,832).

1. RFC 3177 is a suggestion by the IETF; ARIN makes the final policy.
2. Just like extant ARIN policy, RFC 3177 speaks of subscribers and not 
locations.  It doesn't even use the misleading term "site" in that quote.

Thank you for providing a citation in favor of my position :-)

>> If an applicant came back with reasonable justification why their
>> site (i.e. org) needed more than a /48 total, even to the level of a /48
>> per location, I'm confident ARIN would go along with it.  There is
>> nothing in the proposal that prohibits such if it's justified.
> Justification means different things in the IPv4 world and the IPv6 world.
> We need to be careful not to confuse the two.

There's no adequate definition for what it means in the IPv4 world, so how 
can IPv6 be all that different?  We are relying on the ARIN staff to make 
reasonable decisions in both cases, and unless we have an outcry that this 
is not sufficient, let it stand.  We'll never come up with enough rules to 
cover every possible situation, so letting well-trained humans use their 
best judgement is the most efficient solution.


Stephen Sprunk        "Stupid people surround themselves with smart
CCIE #3723           people.  Smart people surround themselves with
K5SSS         smart people who disagree with them."  --Aaron Sorkin 

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