On Sep 17, 2012, at 08:18 , Matthew Kaufman <matt...@matthew.at> wrote:
> On 9/17/2012 5:28 AM, John Mitchell wrote: >> I think people forget how humongous the v6 space is... >> >> Remember that the address space is 2^128 (or >> 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses) to put the in >> perspective (and a great sample that explained to me how large it was, you >> will still get 667 quadrillion address per square millimetre of the Earth's >> Surface. > > Yes. But figure an average subnet has, what, maybe 5 hosts on it? (Sure, > there's some bigger ones, but a whole lot of "my router, my PC, and maybe my > printer" networks too. > > So even if you could use all the top bits (which you can't, as many > combinations are reserved), that's more like 92,233,720,368,547,758,080. And > if you lop off the top three bits and just count the space currently assigned > to Global Unicast, that's 11,529,215,046,068,469,760. Which is 0.02 per > square mm of the earth's surface. Or just over 2 per square centimeter. > > Powers of two get big fast... but they get small fast too. > > Matthew Kaufman >What technology are you planning to deploy that will consume more than 2 >addresses per square cm? >Owen http://xkcd.com/865/ -Davis
