ISP customer assignments

Michael Thomas mike at mtcc.com
Tue Oct 6 00:12:23 UTC 2009


On 10/05/2009 04:59 PM, David Andersen wrote:
> On Oct 5, 2009, at 7:50 PM, Michael Thomas wrote:
>> I'm perplexed. At what size address would people stop worrying about
>> the "finite" address space? 256 bits? 1024 bits?
>>
>> I just don't get it. It's not like people get stressed out about running
>> out of name space in English which is probably more "finite" than ipv6.
>
> Unless you're trying to find a nice, catchy, short domain name. ;-)
>
> But seriously: Many people don't seem to have good intuition about
> really big numbers. Say, on the order of 2^128. The same thing comes up
> in discussions about hash collisions in, e.g., content based naming with
> a 160-bit namespace. I think it's because the numbers are so
> astronomically big, that without some amount of math and having thought
> about it with paper and pencil, people automatically scale the #s into
> terms they can think of as "really big" (like, # of people on earth). So
> when they think about the 128-bit namespace, they apply intuition that
> works for a 35-bit namespace...

Hey, that's are why logarithms are our friends :)

Seriously though, when i was at that big ol' networking company, the size
of the address space was so ridiculously large that hardware and software
people charged with implementing it certainly had no love for it. So it's
not like vendors were cheaping out or something -- it makes their life
quite a bit more, uh, interesting.

Ipv6 *is* what what was learned about ipv4 addresses: make the address
space so astronomically large that nobody could possibly worry.

Curse those logarithms on second thought.

Mike




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