After all our discussion on IRC and coming to a decision to use 10.0.0.0/13 (giving us 16 regions), evilbunny said that we should try and integrate our network with the Australian one. Apparently the Aussies have been kind enough to already have allocated us 10.224.0.0/11, which gives us 2,097,152 IP addresses to use.

The question now is, how do we then in turn subdivide these IP's?

For routing purposes we want to have New Zealand divided into geographical areas. This makes things much easier.
Also, an Wireless Access Point has a limit on the number of Clients that can be connected. This number is subject to much debate, but I think that 30 Clients is a reasonable maximum. Remember, if our Access Point is using DHCP then this is the maximum number of Clients connected at the same time. For Access Points wanting to support more than 30 connected Clients at the same time, then either multiple blocks of 32 have to be assigned, or some other alternative. Why not make blocks of 64 instead of 32? Because 80% of Access Points will not need more than 30, and we don't wish to waste the few IP's that we have.
(Note the difference between 30 and 32 is that we are assigning blocks of 32, but only end up with 30 usable IP's)

So, what do we end up with?

If we choose blocks of 32 for Access Points, this will allow us to have 65536 Access Points in the entire country. Each of these Access Points will have 30 IP addresses. ( This is a /21 )

If we choose instead blocks of 16 for Access Points, this will allow us to have 131072 Access Points in the entire country. Each of these Access Points will have 14 IP addresses. ( This is a /20 )

While 65535 may sound like more addresses than we will ever need, many will be wasted, and this solution will be a permanent one. In 2020 we may be needing more that 65535 addresses, but will be stuck.

I am certain that there are some flaws in the above logic. The numbers above are indicative only, not guaranteed.

There is also another factor, do we just forget about all this complicated IPv4 address space which is all a nasty hack at best, and just use IPv6. That would enable us to use real-world address space, instead of this 10.x.x.x nonsense which means we will never be able to communicate with anyone except the Aussies (and the real-world internet). IPv6 does bring a different set of problems, however.

Joel