[arin-ppml] Draft Policy ARIN-2013-3: Tiny IPv6 Allocations for ISPs

David Farmer farmer at umn.edu
Wed Mar 27 21:34:06 EDT 2013

On 3/27/13 19:40 , Jimmy Hess wrote:
> On 3/27/13, John Curran <jcurran at arin.net> wrote:
>> On Mar 27, 2013, at 7:52 PM, Owen DeLong <owen at delong.com> wrote:
>>    How many customers does an typical xx-small ISP have today?
>>    (xx-small being those ISPs who hold a /22 of IPv4 space)
> Well, logically they could have up to  approximately1000 customers,
> assuming no NAT
> and an average of one /32 per customer.
> The IPv6 equivalent of  1000 /48s     =     a  /38

Well technically 1024, but with an 80% rule that is 819 customers. 
However, with a residential ISP using customer pools and lets say one 
pool of /22 then 512 customers could justify more IPv4, I think.  But 
with /29 pools you would justify more address space with 80% of the /29 
pools allocated or 103; and 50% or more usage in all pools, or 4 
addresses; So that could be as little as 103 * 4 = 412 residential 
customers.  So the CPE for those residential customers are going to 
request what size blocks using DHCPv6-PD, probably /64s mostly today, 
but some might request /56s and hopefully some will request /48s. 
Obviously a /40 wouldn't provide enough /48s, but I'm not sure /48s are 

While on the other had, you would only need 103 /29 business customers 
to justify more IPv4 space.  And a /40 provides more than enough /48s to 
cover this business customer scenario.

So /40 isn't perfect, but it seems reasonable and would allow a business 
case to be built before IPv6 is likely to be the cause of a change in 
fee category.

That's my run of the numbers.


David Farmer               Email: farmer at umn.edu
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