IPv6 Confusion

Kevin Oberman oberman at es.net
Tue Feb 17 15:30:04 CST 2009


> From: Owen DeLong <owen at delong.com>
> Date: Tue, 17 Feb 2009 11:48:49 -0800
> 
> 
> On Feb 17, 2009, at 11:28 AM, Tony Hain wrote:
> 
> > 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
> else".
> 
> >
> >
> >
> > 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:
http://smakd.potaroo.net/ietf/all-ids/draft-nishitani-cgn-00.txt

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.
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751




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