Posted by: Rowan | July 18, 2008

What do you call this number?

Warning! High geek content! [Skip!]

Once you get your head around using colons instead of ‘dot’ (it doesn’t have the same ring, does it?), IPv6 is easy. And ginormous – check this out.

An IPv4 address:
An IPv6 address: 3ffe:1900:a545:3:200:f8ff:fe21:67cf

Take that 203 bit at the start of the IPv4 address, which in hex is cb. So the cb can fit in the start of the IPv6 address where there’s a 3f at the moment. The 185 in hex is b9, which can fit in where the fe in the IPv6 address is. 39 becomes 27 and 74 becomes 4a, so stick 274a in place of 1900 in the v6 address.

So the entire IPv4 internet fits into the 3ffe:1900 part of the IPv6 address.

That means we’ve still got this much spare address space to use up: a545:3:200:f8ff:fe21:67cf. Which is the internet three times over and all based on exponential numbers.

How big is IPv6? Bigger than ginormous, I reckon.

Each digit is in hexadecimal so it uses 4 bits in binary (24). There’s 32 hex digits in the IPv6 address, so that’s (24)32 = 2128 available addresses. That’s this big:


No idea what you’re meant to call a number that big, but it sure solves this problem:

  • 4,294,967,296 is the size of the IPv4 internet now.
  • 6,710,780,968 is the number of people on the planet according to the World Population Clock this evening.

IPv6 ought to give us a bit of headroom.

50,706,820,643,313,605,979,603,566,079 is the number of things I can connect to the IPv6 internet, all for myself. And so can everyone else. If I’m (un?)lucky enough to see the world population double before I croak then I’ll only be able to have 25,353,410,321,656,802,989,801,783,039 addresses. So I’ll probably start with my computers and phone and TV and, um, take it from there.

When we run out of this one – we won’t be worrying about it. Thank God for that. You’d only want to do this once. :-)


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