Waste will kill ipv6 too

Wed Dec 20 21:38:51 UTC 2017

Bill,

You are correct.

As a double check, I divided 340282366920938463463374607431768211456 by 4294967296, getting  79228162514264<tel:79%20228%20162%20514%20264>337593543950336<tel:337%20593%20543%20950%20336>, which is 28.8 orders of magnitude :)

 -mel

On Dec 20, 2017, at 12:58 PM, William Herrin <bill at herrin.us<mailto:bill at herrin.us>> wrote:

On Wed, Dec 20, 2017 at 1:48 PM, Mel Beckman <mel at beckman.org<mailto:mel at beckman.org>> wrote:
I won’t do the math for you, but you’re circumcising the mosquito here. We didn’t just increase our usable space by 2 orders of magnitude. It’s increased more than 35 orders of magnitude.

Hi Mel,

The gain is just shy of 29 orders of magnitude. 2^128 / 2^32 = 7.9*10^28.

There are 2^128 = 3.4*10^38 IPv6 addresses, but that isn't 38 "orders of magnitude." Orders of magnitude describes a difference between one thing and another, in this case the IPv4 and IPv6 address spaces.

Using a /64 for P2P links is no problem, really. Worrying about that is like a scuba diver worrying about how many air molecules are surrounding the boat on the way out to sea.

It's not a problem, exactly, but it cuts the gain vs. IPv4 from ~29 orders of magnitude to just 9 orders of magnitude. Your link which needed at most 2 bits of IPv4 address space now consumes 64 bits of IPv6 address space.

Then we do /48s from which the /64s are assigned and we lose another 3 or so orders of magnitude... Sparsely allocate those /48s for another order of magnitude. From sparsely allocated ISP blocks for another order of magnitude. It slips away faster than you might think.

Regards,
Bill Herrin

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