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minimum IPv6 announcement size
On 9/26/2013 1:07 PM, joel jaeggli wrote:
>
> On Sep 26, 2013, at 12:29 PM, Darren Pilgrim <nanog at bitfreak.org>
> wrote:
>
>> On 9/26/2013 1:52 AM, bmanning at vacation.karoshi.com wrote:
>>> sounds just like folks in 1985, talking about IPv4...
>>
>> The foundation of that, though, was ignorance of address space
>> exhaustion. IPv4's address space was too small for such large
>> thinking.
>
> The first dicussion I could find about ipv4 runnout in email
> archives is circa 1983
>
>> IPv6 is far beyond enough to use such allocation policies.
>
> There are certain tendencies towards profligacy that might
> prematurely influence the question of ipv6 exhaustion and we should
> be on guard against them? allocating enough /48s as part of direct
> assignments is probably not one of them.
That's just it, I really don't think we actually have an exhaustion risk
with IPv6. IPv6 is massive beyond massive. Let me explain.
We have this idea of the "/64 boundary". All those nifty automatic
addressing things rely on it. We now have two generations of hardware
and software that would more or less break if we did away with it. In
essence, we've translated an IPv4 /32 into an IPv6 /64. Not great, but
still quite large.
Current science says Earth can support ten billion humans. If we let
the humans proliferate to three times the theoretical upper limit for
Earth's population, a /64 for each human would be at about a /35's worth
of /64's. If we're generous with Earth's carrying capacity, a /36.
If we handed out /48's instead so each human could give a /64 to each of
their devices, it would all fit in a single /52. Those /48's would
number existance at a rate of one /64 per human, one /64 per device, and
a 65535:1 device:human ratio. That means we could allocate 4000::/3
just for Earth humans and devices and never need another block for that
purpose.
That's assuming a very high utilisation ratio, of course, but really no
worse than IPv4 is currently. The problem isn't allocation density, but
router hardware. We need room for route aggregation and other means of
compartmentalisation. Is a 10% utilisation rate sparse enough? At 10%
utilisation, keeping the allocations to just 4000::/3, we'd need less
than a single /60 for all those /48's. If 10% isn't enough, we can go
quite a bit farther:
- 1% utilisation would fit all those /48's into a /62.
- A full /64 of those /48's would be 0.2% utilisation.
- 0.1%? We'd have to steal a bit and hand out /47's instead.
- /47 is ugly. At /52, we'd get .024% (one per 4096).
That's while maintaining a practice of one /64 per human or device with
65535 devices per human. Introduce one /64 per subnet and sub-ppm
utilisation is possible. That would be giving a site a /44 and them
only ever using the ::/64 of it.
Even with sloppy, sparse allocation policies and allowing limitless
human and device population growth, we very likely can not exhaust IPv6.