Re: Terminology [Re: Some Comments on ID/Loc Separation Proposals]

["Spencer Dawkins" <spencer@mcsr-labs.org>]

Dear Brian,

Excellent. So we have someone who can channel the spirit of NSRG...

You may have been buried while traveling and recovering (and I
apologize for contributing to your e-mail load), but I wonder if you
could comment on my question about "dual-stack" - is a dual-stacked
host one thing or two, in the NSRG sense of the term "stack"?

Spencer

----- Original Message ----- 
From: "Brian E Carpenter" <brc@zurich.ibm.com>
To: "Dave Crocker" <dcrocker@brandenburg.com>
Cc: <multi6@ops.ietf.org>
Sent: Saturday, December 06, 2003 10:26 AM
Subject: Terminology [Re: Some Comments on ID/Loc Separation
Proposals]


> After some travel and some flu, I've caught up with this thread, but
I
> think it's clearer to comment on Dave's original post.
>
> Firstly, co-chair hat on, we need consistent terminology. When we
use a
> word, we should all try to use it in the same sense. In the end, we
may need
> a specific multi6 terminology draft. It is also best if we use
existing
> definitions rather than inventing our own with subtle changes. So,
for example,
> if we do use "stack" let's agree on the NSRG definition unless we
have a
> very strong reason to change it. Otherwise, confusion lies ahead.
>
> Co-chair hat off. Personal comments below.
>
> Dave Crocker wrote:
> >
> > Folks,
> >
> > draft-crocker-mast-analysis (which will be
> > draft-crocker-multiaddr-analysis in its next version) has a
section
> > for defining some terms.  The section has been prompted by exactly
the
> > kind of vagueness that the current thread is also trying to fix.
> >
> > My primary interest is in having precise definitions that we all
find
> > useful and use consistently. Some of the current versions of
> > definitions in the draft are:
> >
> >    Endpoint
> >
> >            refers to "the fundamental entity of and end-end
> >            communication" [EID]. It is an end-system that
participates
> >            in an association. Endpoints are distinguished from
> >            intermediate, infrastructure nodes and from hosts.
>
> Yes. But this is too generic to be really very useful... and trying
to
> get more precision always ends in a rat hole.
>
> >
> >    Identifier
> >
> >            refers to a unique label for an endpoint. The label is
used
> >            simply for distinguishing one endpoint from another.
>
> But to use OSI terminology, this doesn't tell me enough, because I
don't know
> whether you are talking about a layer 2, 3, 4 or higher endpoint.
That's the
> advantage of "stack" - we know it's layer 3.
>
> >            Because a locator is usually globally unique, it might
be
>
> I wish. But every single time I travel, I find myself ending up with
an
> identifier that *isn't* globally unique. I don't think "usually" is
at all
> accurate. "supposedly unique" might be more accurate.
>
> >            able to serve as an identifier. However this use will
often
> >            suffer administrative and referential limitations as a
> >            global identifier for mobile endpoints. This is
exemplified
> >            by the current problems experienced with the dual role
of
> >            IP Addresses.
>
> I don't think so. You're correct of course that id/loc overlap is a
problem
> with mobility. But the problems *today* are caused mainly by
non-uniqueness
> and that is what is exemplified each time you hook up in a hotel.
>
> >
> > Suggestions for improving the text are eagerly sought.
> >
> > As with others, I do not think it is useful to have ID refer to an
> > interface.  Stack, endpoint or process all seem more helpful.
>
> True. Interfaces are a somewhat elastic concept and not interesting
> at systems level. Personally I prefer NSRG-stack to endpoint,
because
> as mentioned above it has more precision.
>
> >
> > Speaking of 'stack', what definition text would folks like.  The
NSRG
> > paper introduces the construct nicely, but I'm not sure the text
there
> > is what we should live with.
>
> Do you have precise criticisms of that definition?
>
> >
> > For that matter, what is the difference between endpoint and
stack?
>
> As an ex-NSRG member, I can tell you that "stack" was chosen because
> people couldn't reach precise consensus on what "end point" means.
>
>    Brian
>
>