Dual stack IPv6 for IPv4 depletion

Wed Jul 8 23:45:08 UTC 2015

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.

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.

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.

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.

Regards,
Israel G. Lugo

P.S.: I'm 100% for IPv6 and $dayjob has been fully dual stacked for 10
years now.