Lloyd Wood wrote:
> On Wed, 8 Dec 1999, Ed Gerck wrote:
>
> > The very concept of data needs thus to revisited. Suppose we define data as the
> > *difference* D2 - D1 that can be measured between two states of data systems.
> > Then, it can be shown that this difference can be measured by means of a
> > communication process only if 1 and 2 are two states of the same closed system.
>
> Since not all system state is communicated and any communication is a
> near-minimum abstraction of system state, this idea is a non-starter.
I understand your doubts; this is a new approach. But communication is
not a "near-minimum abstraction of system state" -- whatever you mean
to communicate by that ;-) The very failure of your communication in that
phrase (and, my very failure to communicate to you in my phrase) exemplifies
my phrase, however.
> > When they are not, NATs are a solution to create a third-system, a common
> > reference between 1 and 2. Which can be conceptual or physical or both, but is
> > needed. In this formalism, a numerical value for data can be defined even though
> > 1 and 2 may belong to different systems, or even though the data systems may be
> > open -- the only restriction is to have a common reference.
> >
> > This is the mind-picture we need to overcome IMO -- that data is absolute. It is
> > not and this answer implies that we need to find "data laws" in order to describe
> > exchanges of data much in the same way as we needed to develop Thermodynamic
> > laws in order to describe exchanges of energy (itself, not an absolute concept,
> > either).
>
> Absolute zero always seemed pretty damn absolute to me.
There is no absolute value of energy associated with absolute zero
temperature -- if that is what you mean. There are many quantities
which are not absolute, distance is another example (besides
energy and data). Phase is another. But there are absolute
quantitites, of course.
> Taking your energy analogy further and better, NATs (and firewalls)
> are the protocol equivalent of Maxwell's demons;
No. This analogy is not correct. Note also that Maxwell's demon has
been proved not to be possible, even theoretically.
> > What I meant is not this. What I meant is an ab initio model of data in
> > network systems, where NATs are one instance of a third-system that is
> > *needed* in order to provide a common but quite arbitrary reference for
> > "measuring" data between different systems, without requiring any
> > change to them. In such a formalism, there are data levels NATs can handle
> > and others it cannot, try as one may -- which needs to be recognized and
> > provided for each case, by yet other objects.
>
> For every type of molecule or energy level you might encounter, you
> have to add another demon.
There are no demons here. If you agree that data is not absolute then
my explanation follows. If you do not agree, then please tell me if
"2=2" is true or false -- it is a simple expression, a simple data point
given by "2=2". But your answer, whatever it is, will prove it is
not absolute.
What is the significance of this? Not to make matters more complicated but
to recognize that NATs are not demons ;-)
In other words, either we have *one* closed data system (IPv4, IPv6, etc.) where
we can easily define data values by difference in data states (where an
arbitrary value of zero is assigned to a system-wide reference state), or
we have *many* systems where we need NATs to provide reference states
between different systems in order to communicate between them.
Since IPv6 defines a larger system, it can encompass a series of different
IPv4 systems linked by NATs. However, since we *do* expect to encounter
IPv4 systems, even if IPv6 is extremely sucessful (say, takes over 80% of
the universe), then it follows that we will always need NATs to provide a
common reference between different systems. Thus, it is worthwhile IMO
to model them and use them well, not demonize them :-)))
Cheers,
Ed Gerck
