Re: [RRG] Six/One Router Design Clarifications

[Brian E Carpenter <brian.e.carpenter@gmail.com>]

On 2008-07-17 18:04, Lixia Zhang wrote:
...
> it seems to me that a few issues need to be further sorted out here.
> 
> 1/ what is the definition of "NAT" here in the context of IPv6? I suppose it is a different one from v4 NAT that uses
> non-unique addresses?

Well, there's no definition of IPv6 to IPv6 NAT (fortunately). But
as far as I can see, uniqueness is not really the problem - it's
simply the assumptions that are made in so many places that both ends
(or even all N ends) of a communication see the same addresses for
the same interfaces.

> 
> 2/ I wonder which position is being argued here regarding applications that embed IP addresses inside.  Independent from
> six/one router or not, it seems to me that, whether one likes it or not, IPv6-IPv4 packet level translation is likely to be
> needed for some long time to come.

Yes, so in the V6OPS and BEHAVE discussions of how to replace NAT-PT,
I think we've more or less agreed on a version of "first, do no harm"
which is "nothing in v6/v4 translation should do *more* harm than
a traditional v4/v4 NAT." That doesn't change the strong desire to avoid
v6/v6 NAT.

On 2008-07-17 18:15, Lixia Zhang wrote:

> On Jul 16, 2008, at 8:27 PM, Brian E Carpenter wrote:
> 
>>> 
>>> PS:  FWIW, I understand issue (c) as being of less grave nature than issues (a) and (b).  Issue (c) is an implementation
>>> issue, NOT an architectural issue like issues (a) and (b).
>> 
>> Absolutely not. It's an architectural issue in the session layer, when session IDs have no universality.
> 
> let me understand this better: my understanding is that six/one router (it ought to be renamed to just IPv6 Address
> translator, or 6AT) performs a one to one matching.  So although the exact value of the "ID" may not be exactly the same
> before or after an 6AT, nonetheless the session is uniquely identified -- would that be considered as having universality?

In my opinion, not if the two ends have a different opinion
about the addresses being used, because we use addresses as
identifiers.

> 
> Lixia PS: in the above I used Brian's terminology, but my personal view is that, in the long run, session layer should move
> away from using IP address entirely.

I completely agree, but the problem is that this isn't how the
Internet has been constructed. I'm very pessimistic about changing
this (and it surely isn't the routing community that can change all
the applications).

     Brian

--
to unsubscribe send a message to rrg-request@psg.com with the
word 'unsubscribe' in a single line as the message text body.
archive: <http://psg.com/lists/rrg/> & ftp://psg.com/pub/lists/rrg