minimum IPv6 announcement size

Tue Oct 1 18:33:44 UTC 2013

On Oct 1, 2013, at 11:11 , William Herrin <bill at herrin.us> wrote:

> On Tue, Oct 1, 2013 at 12:04 PM, Rob Seastrom <rs at seastrom.com> wrote:
>> William Herrin <bill at herrin.us> writes:
>>> IPv4 jumped from 8 bits to 32 bits. Which when you think about it is
>>> the same ratio as jumping from 32 bits to 128 bits.
>> 
>> Jumping from 8 bits to 32 bits (1:16mm) is the same ratio as would be
>> jumping from 32 bits to 48 bits (also, 1:16mm).
> 
> Hi Rob,
> 
> And yet we're allocating /19's where previously we allocated space
> that added up to /7's and /48's where previously we allocated /24's.
> My math may be flawed but the pattern is there all the same.

Not exactly...

We're allocating /16s and/or /20s where previously we allocated space
that added up to /7's, but, the holders of the /7s were coming back for more
and more on a regular basis. I don't believe anyone holding a /16 or /20
of IPv6 has come back for another allocation at all and I would be surprised
if such an organization were to do so in the next 5 years or so.

We're allocating /48s where previously we allocated roughly /16-/24.

Any effort at making direct comparisons between IPv4 and IPv6 number utilization
is flawed because there is, by definition, nothing approximating a simple ratio
between the two.

> 
> 
>> Going from 32 bits to 128 bits is 1:79228162514264337593543950336 which
>> is not even remotely the same ratio.
> 
> You know enough about IPv6 to realize that we didn't go from 32 bits
> to 128 bits, we went from either 24ish bits to 48 or 28ish bits to 64,
> depending on how you look at it. While IPv6 is capable of working the
> same as IPv4, that's not how we're actually using it.

Both of those estimates are also flawed.

> More, growth has not been linear since IPv4's advent and is not (by
> anyone reasonable) projected to be linear or sub-linear in IPv6.
> Computing a linear ratio as if that were representative of the
> expected lifetime of the new address space does not paint an honest
> picture.

Nor does any effort to apply a simple ratio between IPv4 and IPv6.

There are sufficient differences in the allocation algorithms and counting
methods between the two that an apples to apples comparison of allocation
policies simply isn't possible.

Owen