IPv6 Confusion

Scott Howard scott at doc.net.au
Tue Feb 17 18:26:33 UTC 2009

I can't help directly with your biggest question, but there's a smaller
point here that seems to come up a lot and I think is important to

On Tue, Feb 17, 2009 at 8:59 AM, Carl Rosevear <
Carl.Rosevear at demandmedia.com> wrote:

> I can't see why hosts would need any more addresses than today but maybe
> I'm missing something because a lot of addressing models sure allow for a
> huge number of unique addresses per host.

According to your website your head office is located at "1333 2nd St.,
Suite 100".

Is there a 1331 2nd Street?  Or a 1335?  Or even a Suite 99?

Or has the street addressing system been created in a wasteful manner in
order to allow flexibility in addressing and allow the numbers themselves to
be more than just numbers?

Just like street numbers, IPv6 is a near limitless resource, which allows
for the address assigned to be more than just a simple, single address.
Yes, this results in some "waste", just like having to write "1333" in your
address where "17" might have sufficed.  IPv6 assigns a /something to each
"thing", in the same way as many areas in the US simply assign 100 numbers
to each block.

In that sense IPv6 requires a mind-set change from IPv4 - you can stop
thinking in terms of the absolute minimum requirements (eg, a single IP
address in v4 because they are a scarce commodity) and start thinking about
what works best for the larger environment (such as just handing out a /64
to each network and allowing autoconfig to handle the rest).  Is that
wasteful?  Hell yeah!  Does it matter?  No!

The bigger question here is of course what size "/something", and what is a
"thing", and as recent discussions here and elsewhere have proven there's
still some contention over those questions - especially around home users.
The problem is that as an industry there simply hasn't been enough IPv6
deployment done to know what will work and what will not - or what is "best"
(for some definition of "best")

I'm sure many of us were around in the days when if even a smaller customer
wanted a network routed you were just as likely to either give them a class
C, or even to get them to register their own class C - because at the time
we thought that was the right thing to do.  Over the years as the commercial
Internet grew we leant what was the "best" thing to do in most cases, and
the same business who 15 years ago was registering their own class C  would
today probably get gives a single IP address - possibly even a dynamic one!
Of course the hardware also changed with the times, so that now the $30
router you can buy at Walmart has NAT, DHCP, uPNP and the ability to update
DDNS all buit in to make the model work.

Odds are what is best is going to be "best" for IPv6 will be a similar
iterative approach - the model the first round of IPv6 ISPs roll out will
probably not be the same as the one we're using in 5-10 years.  Part of this
will be due to limitations in the infrastructure (not the least the
home-user CPE), but part of it of it will simply come down to experiences,
and learning what does and doesn't work well.  Today you'll find numerous
RFCs and IETF drafts telling you in theory how it could/should work, but
until there's more people doing it these are little more than theory...


More information about the NANOG mailing list