ISP customer assignments

Owen DeLong owen at
Mon Oct 5 22:47:29 UTC 2009

It's very likely that they won't understand, won't have to, and will  
still need them.

Let's face it, most customer's don't know what an IP address is,  
really, but, they
still need them and they still use them all the time.

It is, as someone else stated, very likely that there will be home  
routers that
have multiple zones on multiple interfaces each of which gets a  
different /64
from a /56 or /48 handed to it by the upstream DHCP-PD box.


On Oct 5, 2009, at 11:10 AM, Brian Johnson wrote:

> What would be "wrong" with using a /64 for a customer who only has a
> local network? Most home users won't understand what a subnet is.
> - Brian
>> -----Original Message-----
>> From: wherrin at [mailto:wherrin at] On Behalf Of
> William
>> Herrin
>> Sent: Monday, October 05, 2009 11:58 AM
>> To: Brian Johnson
>> Cc: nanog at
>> Subject: Re: ISP customer assignments
>> On Mon, Oct 5, 2009 at 11:27 AM, Brian Johnson <bjohnson at>
>> wrote:
>>> From what I can tell from an ISP perspective, the design of IPv6 is
>> for
>>> assignment of a /64 to an end user. Is this correct? Is this how it
>> is
>>> currently being done? If not, where am I going wrong?
>> No. A /64 is one *subnet*. Essentially the standard, static size for
>> any Ethernet LAN. For a customer, the following values are more
>> appropriate:
>> /128 - connecting exactly one computer. Probably only useful for your
>> dynamic dialup customers. Any always-on or static-IP customer should
>> probably have a CIDR block.
>> /48 - current ARIN/IETF recommendation for a downstream customer
>> connecting more than one computer unless that customer is large  
>> enough
>> to need more than 65k LANs.
>> /56 - in some folks opinion, slightly more sane than assigning a 65k
>> subnets and bazillions of addresses to a home hobbyist with half a
>> dozen PC's.
>> /60 - the smallest amount you should allocate to a downstream  
>> customer
>> with more than one computer. Anything smaller will cost you extra
>> management overhead from not matching the nibble boundary for RDNS
>> delegation, handling multiple routes when the customer grows, not
>> matching the standard /64 subnet size and a myriad other obscure
>> issues.
>> Regards,
>> Bill Herrin
>> --
>> William D. Herrin ................ herrin at   
>> bill at
>> 3005 Crane Dr. ...................... Web: <>
>> Falls Church, VA 22042-3004

More information about the NANOG mailing list