IPv6 Confusion

From: Owen DeLong <owen@delong.com>
Date: Tue, 17 Feb 2009 11:48:49 -0800

> While people frequently claim that auto-config is optional, there are
> implementations (including OS-X) that don't support anything else at
> this
> point. The basic message is that you should not assume that the host
> implementations will conform to what the network operator would
> prefer, and
> you need to test.

I can configure OS-X statically, so, that simply isn't true.

What is true is that there are many implementations which do not (yet)
support DHCPv6. That is not the same as "don't support anything

> One last comment (because I hear "just more bits" a lot in the *nog
> community)... Approach IPv6 as a new and different protocol. If you
> approach
> it as "IPv4 with more bits", you will trip over the differences and be
> pissed off. If you approach it as a "different protocol with a name
> that
> starts with IP" and runs alongside IPv4 (like we used to do with
> decnet,
> sna, appletalk...), you will be comforted in all the similarities.
> You will
> also hear lots of noise about 'lack of compatibility', which is just
> another
> instance of refusing to recognize that this is really a different
> protocol.
> At the end of the day, it is a packet based protocol that moves
> payloads
> around.
The problem here, IMHO, stems from the fact that unlike DECnet,
Appletalk, SNA, et. al., IPv6 is intended as a replacement for
IPv4. (None of the other protocols was ever intended to replace
any of the others).

As a replacement, the IETF realized that at the current scale of the
internet when they began designing IPv6, a flag day conversion
(like what happened when we went to IPv4) was not possible.
Unfortunately, the migration plan set forth by the IETF made many
assumptions (especially on vendor preparedness and rate of
adoption prior to IPv4 runout) that have not proven out, so, the
"Everyone who has IPv4 starts running dual-stack before we
need any IPv6 only connectivity" plan is not going to prove out.

More unfortunately, there is no real contingency plan for how
migration happens absent that scenario and we are, therefore,
in for some interesting times ahead.

While this is very true, at least the IETF has recognized the problem
and the BEHAVE WG is trying to come up with some way of getting out of
the trap we have worked our way into.

The big iron folks are proposing something called "Carrier Grade
NAT". This one REALLY frightens me, but I understand a couple of hardware
manufacturers are planning on building such a monster. It might actually
work, but the amount of state carried strikes me as in invitation to
disaster. There was a draft on CNG, but it expired last month. A copy is
still available at:

Also, a proposal for a different approach is at:
http://mice.cs.columbia.edu/getTechreport.php?techreportID=560 (PDF)

If you are really concerned about where we go whan v4 address space is
exhausted, I strongly urge you to look at all of these issues.

Also, a proposal for a different approach is at:
http://mice.cs.columbia.edu/getTechreport.php?techreportID=560 (PDF)

which has an internet draft, draft-ymbk-aplusp-02.txt


The really scary thing is that deploying carrier-grade NAT might be cheaper
to the service provider than rolling IPv6 to its residential subscribers.


The really scary thing is that in areas where there are only two major ISPs, both might go for CGN and then you have no choice.

The important thing is to have proper competition, that's the way innovation gets into the market.

On the other hand, I have little problem in seeing a future with different service offerings, one being "IPv4 only behind CGN" and another being "globally routable IPv4 address with 6to4 support" and a third being "globally routable IPv4 address with native IPv6 and a /56 (or /48)".