AW: AW: [address-policy-wg] IPv6 allocations for 6RD

> Seems a bit questionable to me to allocate the IPv6 
> equivalent of class As when we haven't the slightest idea how 
> things will evolve and we have experience in blowing through 
> an "inconceivably large address space".

The IPv6 equivalent of a class A address block is a /8. We
are not talking about allocating /8s to anyone, we are
mainly talking about allocating /24s which are the equivalent
of IPv4 class C blocks.

This is one area where the IPv4 arithmetic and IPv6 arithemetic
match up nicely. If you are worried about using up all the
addresses, an IPv6 /24 and an IPv4 /24 use up the same percentage
of the total address space. The very fact that we are discussing
allocations in the region of /19 to /24 demonstrates the 
success of IPv6 in expanding the size of the address space.

In IPv4, a really big ISP would get a /8. In IPv6 we can 
handle a really big ISP with one /13 and a medium sized
ISP can fit into a /32, which in IPv4 can only handle a 
single host.

When discussing the risk of runout, you have to look at
actual numbers and actual percentages of the total number
space. I suggest examining some of Geoff Huston's work in
more detail.

--Michael Dillon