ISP customer assignments

Michael Dillon wavetossed at
Mon Oct 5 17:06:21 CDT 2009

>> This is where I think there is a major disconnect on IPv6.   The size of
>> the pool is just so large that people just can't wrap their heads around it.

Why bother wrapping your head around it? Do you count how many computers are
in your house? Did you remember to count the CPU inside the PC keyboards?
Does it matter?

IPv6 addresses are not for you, they are not for your house, and they are not
for your network. IPv6 addresses are for network interfaces, physical and
virtual, and these interfaces are free to use multiple IPv6 addresses at the
same time for various reasons. Why even try to count that unless you are
a protocol designer?

Fact is that IPv6 is dead simple. You, the ISP, get a /32 from ARIN unless
you are really big. You give your customers a /48. If you have a really, really
big number of really small (consumer) customers, then you can add another
level of complexity and give them a /56. Every time you set up a new network
segment (broadcast domain) you assign it a /64. All /64s in one building should
really be out of the same /48 unless you are segregating internal use networks
from transit service networks, in which case there would be two /48s for the

Forget counting bits except between /32 and /48 for your ISP business and
between /48 and /64 for your network building business.

--Michael Dillon

More information about the NANOG mailing list