[101409] in North American Network Operators' Group
RE: Assigning IPv6 /48's to CPE's?
daemon@ATHENA.MIT.EDU (michael.dillon@bt.com)
Thu Jan 3 07:22:51 2008
Date: Thu, 3 Jan 2008 12:25:39 -0000
In-Reply-To: <20080103.123433.41673933.sthaug@nethelp.no>
From: <michael.dillon@bt.com>
To: <nanog@merit.edu>
Errors-To: owner-nanog@merit.edu
> > No, it gives them 16 bits for subnetting. Everybody gets
> > 64 bits for addressing because everybody (except oddballs and=20
> > enevelope pushers) uses a /64 subnet size. Since 64 bits=20
> are more than=20
> > anyone could ever possibly need for addressing and 16 bits is more=20
> > than an end site could ever possibly need for subnetting,=20
> the /48 is=20
> > an ideal allocation size.
>=20
> As should be clear from the previous discussion, there are=20
> plenty of us who disagree here, and lean towards /56 for end=20
> users (typically residential customers) while business users=20
> would get a /48 or more based on need.
I wouldn't say that is a disagreement, more of an extension.
In other words, many of us believe that 16 bits per end site
is an ideal customer allocation, but feel that residential=20
customers in their home are not in any way penalized by
reducing this to 8 bits. They still have scope for a significant
amount of subnetting even in extreme cases like constructing an
inlaw suite plus operating a family business out of the home.
I do agree that /56 per residential customer is the ideal allocation
for a mid-sized to large ISP that has a large number of residential
customer sites on its network. I expect that most such ISPs will
implement a model with /48's to business and /56's to residential
addresses. But I also expect that smaller ISPs or those who mainly
supply business access services, will find it simpler to just give
everyone a /48.
The only place in which people have noted that there is a possibility
of running out of bits in the existing IPv6 addressing hierarchy
is when they look at a model where every residential customer gets
a /48. In that scenario there is a possibility that we might runout
in 50 to 100 years from now. If only the ISPs with a large residential
user population go to a /56 per residential site, then we have solved
the problem.
--Michael Dillon
