Re: terminology proposal: NAT+PT (or NAT64 ?)

[Rémi Després <remi.despres@xxxxxxxxxx>]

Keith Moore a écrit :

"IPv4 mapped" addresses (those of the form ::ffff:{ipv4 address}) should
never appear on the wire.  Embedding an IPv4 address within an IPv6
address might make sense in certain cases, but it doesn't work in general. 
  

If using them on the wire is useful, without any "identified" problem, why not ?
But if you already know of such problem, I am of course interested.

As a matter of fact, I like your choice of "NAT-XY" to describe the
general mechanism you are working on (if I got it right). This IMHO
shows the expressive power of generalizing Alain's approach,
introducing a dash, as you did, to separate IP versions
identifications from "NAT". What about NAT-XX, NAT-XY, NAT-44,
NAT-64, NAT-46  ? I would be very happy if this debate, introduced by
Ran Atkinson, would end up with such a step against confusion.
    

To me NAT-64 and NAT-46 are even more confusing, because I can't tell
which end is which.  If sessions can be initiated from either the v4 or
the v6 side (which IMO is a necessary condition for the translation box
to be effective), what's the significance of the first digit vs. the second?
  

This is the crux of the matter.
Is the NAT function inherently oriented or not?
In my understanding it definitely is, and has to be so.
Existing NAT-44s provide only ONE substitute address, that of what I call the "session initiator" host (the "pivate" address of a connection is changed, and the "public"address isn't).

NAT-64 is the one which is  NECESSARY for IPv6-only clients to access IPv4-only servers.
(There may be other needs but this one is clearly identified , and IMO its solution does deserve a non ambiguous name)
In this case, the "session initiator" is again the one whose address is replaced by a NAT provided one, and that is the IPv6 only host.

Note that it is on purpose that I use "sessions initiator" and not "connection initiator".
This takes into account that some application protocols ( FTP, SIP... ) are such that address and/or port numbers may be exchanged as data, for subsequent UDP or TCP connections.
The "session initiator" of a connection is the host which initiated the NAT address-port reservation for the connection.
Some other names, e.g. NAT-state initiator, or whatever, could also do, but "session initiator" sounds intuitive enough to me.

Rémi

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