Dual stack IPv6 for IPv4 depletion

Thu Jul 9 01:15:30 UTC 2015

> On Jul 8, 2015, at 15:34 , Israel G. Lugo <israel.lugo at lugosys.org> wrote:
> 
> 
> On 07/05/2015 06:26 PM, Owen DeLong wrote:
>>> On Jul 4, 2015, at 23:51 , Valdis.Kletnieks at vt.edu wrote:
>>> 
>>> Put their IPv4 behind a NAT and a globally routed /56.
>>> 
>>> There, FTFY. :)
>> Or better yet globally routed /48.
>> 
>> /56 is still a bad idea.
>> 
>> Owen
> I've read this many times and am aware it's the standard recommendation.
> Makes perfect sense for the customer side, as it would be hard for him
> to subnet properly otherwise.
> 
> Doesn't seem to make sense at all for the ISP side, though. Standard
> allocation /32. Giving out /48s. Even if we leave out proper subnet
> organization and allocate fully densely, that's at most 65,536 subnets.
> Not a very large ISP.

If you’re trying to build a decent sized ISP in a /32, you’re doing it wrong.

/32 is not the “standard size” — It’s the MINIMUM size.

> 
> You can say "get more blocks", or "get larger blocks". Sure, let's give
> each ISP a /24. That lets them have up to 16M customers (and that's
> still subnetting densely, which sucks rather a lot). Doesn't leave that
> many allocation blocks for the RIRs to hand out, though.

If you really think we have 16.7 Million ISPs on the planet, I think you
badly miscounted. In fact, if you think we have 1 million ISPs that have
more than 1 million customers, I’d say you’ve badly miscounted something.

What am I missing?

In terms of ISPs that need to support 16M customers, let’s assume everyone
on the planet has 32 ISP subscriptions of some form or another. (work, home,
tablet, phone, dongle, whatever… I’m pretty sure 32 is generous).

Let’s assume EVERYONE on the planet is connected.

That’s 7 Billion * 32 = 224 Billion total customers.

Now let’s sparse-allocate 24s at the rate of 4 million customers per /24.

224,000,000,000 / 4,000,000 = 56,000

We need a total of 56,000 /24s to cover the total population.

That still leaves us with 16,721,216 /24s. We barely made a dent in the
number of /24s.

Please explain to me again where the problem is with handing out /48s?

> People usually look at IPv6 and focus on the vast numbers of individual
> addresses. Naysayers usually get shot down with some quote mentioning
> the number of atoms in the universe or some such. Personally, I think
> that's a red herring; the real problem is subnets. At this rate I
> believe subnets will become the scarce resource sooner or later.

I’ve done the math on the prefix side. See above… Clearly you haven’t.

> Sure, in the LAN side we'll never have to worry about address scarcity.
> But what's the point of having addresses to spare, if it just means
> you've got to start worrying about subnet scarcity? If the goal was
> never having to worry about counting anymore, I propose that 128 bits is
> far too little. Should've gone a full 256 and be done with it.

Respectfully, I think that the math above shows that you are not correct
in this assertion.

Owen