[ppml] alternative to 2005-1

[Scott Leibrand]

On 02/09/06 at 12:45pm -0500, Thomas Narten <narten at us.ibm.com> wrote:

> > >  Also, why do you specify /19 for #5 under 6.5.8.1?  Shouldn't someone with
> > >  a IPv4 PI /22 be able to get an IPv6 /48?
>
> > It is just a line in the sand.
>
> > I personally believe that a /22 is too small, however there are
> > those who will think that an org with a /22 should be able to obtain
> > a IPv6 PI address space.
>
> Note: a /22 is only 2^10 addresses, or 1024. That's a pretty darn small
> site, if you ask me.

So what?  We give them a routing slot for IPv4.  Why shouldn't they get
one in IPv6?

> A /19 is somewhat better, namely, 8192.
>
> Still, I fear there are 10s to 100s of thousands of organizations in
> this size. Remember, each entity with a PI assignment translates into
> a routing slot in the DFZ.

Regardless of how many such organizations exist, the number of IPv4 PI
/22's vs. /19's tells you how many such organizations would qualify for
IPv6 PI space under this type of policy.  The number isn't that large, and
with a /22 requirement limits you to at maximum the same number of IPv6 PI
blocks as we have IPv4 PI blocks.  IMO those kinds of numbers are small
enough to deal with effectively without wholesale PI filtering, unlike in
the IPv6-PI-for-everyone case.

> Heck, even if we set a threshold of /16, we'd be saying "anyone who
> can justify a class B assignment". I suspect that the number of end
> sites meeting that criteria is pretty large.

But significantly smaller than the number of sites for whom PI space is
necessary to avoid significant renumbering pain when changing ISPs.

> I'd feel a lot more comfortable picking a threshold if I had a rough
> idea of how many entities we're talking about who would qualify. Given
> the above, even /19 sounds too low.
>
> In the absence of data, I'd say be _very _ conservative, e.g., start
> with a /16 (or higher).

We have plenty of data.  Just count the number of netblocks in the current
IPv4 table.  If you want to be more precise, count the number of /22's and
larger in the table from the ranges reserved for IPv4 PI assignments.

-Scott