# Using /126 for IPv6 router links

Andy Davidson andy at nosignal.org
Mon Jan 25 09:12:49 UTC 2010

```On 24/01/2010 02:44, Larry Sheldon wrote:
> On 1/23/2010 8:24 PM, Owen DeLong wrote:
>> 64 bits is enough networks that if each network was an almond M&M,
>> you would be able to fill all of the great lakes with M&Ms before you
>> ran out of /64s.
> Did somebody once say something like that about Class C addresses?

No.  There are only 2,097,152 Class C networks.

Assuming all M&Ms are spheroids of uniform oblate nature, radius major
axis=6mm, minor axis=3mm.  Volume is (4/3)Pi (Major^2) Minor
(http://en.wikipedia.org/wiki/Spheroid#Volume)

They will be poured into a great lake of your choice, and we will assume
random close packing (agitation mechanisms are probably best discussed
off-list) and a (generous, but the article insists) void fraction of 32%.
(http://en.wikipedia.org/wiki/Random_close_pack)

Volume of m&m = 0.452cm^3, occupies 0.665cm^3.

Lake Erie is 484km^3
http://www.epa.gov/glnpo/factsheet.html

1 km^3 = 1,000,000,000,000,000 cm^3

484,000,000,000,000,000 * 0.665 = 321,860,000,000,000,000 m&ms needed to
fill this lake.

There are 4,294,967,296 /64s in my own /32 allocation.  If we only ever
use 2000::/3 on the internet, I make that 2,305,843,009,213,693,952
/64s.  This is enough to fill over seven Lake Eries.  The total amount
of ipv6 address space is exponentially larger still - I have just looked
at 2000::/3 in these maths.

THE IPv6 ADDRESS SPACE IS VERY, VERY, VERY BIG.

** Can we please now just go ahead and roll out some ipv6 services ? **

Thanks
Andy

```