Whole Lotta IPv6

Wow, I've just had the pleasure of receiving my allocation from APNIC of a /32 prefix of IPv6 address space. That's a lot of address space.

It's a hard thing to think about how big IPv6 address space is, so to put it into perspective, I'll equate it to the size of a single LAN. Now in IPv4 world, a single LAN is usually a /24 which gives 254 hosts on a network. That's a good number for most applications. When we move to IPv6, to support auto configuration, the recommended number of bits was set at 64 bits. Already that's mind boggling-ly huge but ignoring that for now, we can use a /64 as the basis for measuring the size of various IPv6 prefixes.

So a single IPv6 LAN is 1 /64 prefix. The recommended allocation for enterprise networks is a /48 which adds 16 more bits. So this means we have potentially 65,436 IPv6 LANs in a /48 prefix.

Can you see where I'm going with this?

My allocation is a /32 because we are a data center and we allocate address space to clients. So this is 16 more bits again from  a /48. One way of looking at it is that there are 65,536 /48s in a /32 or 4,294,967,296 IPv6 LANs in a /32.

If you recognize that big number, you're doing well, it's the total number of IPv4 addresses possible. So my /32 IPv6 allocation has as many LANs as there are IPv4 addresses possible.

Wow. Each one of these IPv6 LANs is also stupendously big but lets not think about that!

To top it all off, this is just a very small piece of the IPv6 global pool. Is it sinking in how big it all is now? There's just so much more room in IPv6 land to spread your stuff out without worrying about conserving every last bit.

Now I just need to renumber everything!