RE: Persistent or opportunistic IDs

[Geoff Huston <gih@telstra.net>]

At 02:03 AM 7/05/2004, marcelo bagnulo wrote:
> Hi Iljitsch,
>
> > De: owner-multi6@ops.ietf.org [mailto:owner-multi6@ops.ietf.org]En
> > nombre de Iljitsch van Beijnum
> >
> > Yesterday at the RIPE meeting Geoff talked about the difference between
> > doing address agility using long-lived identifiers vs pragmatic,
> > short-lived identifiers. This is indeed a useful way to classify multi6
> > solutions. Pragmatic identifiers would generally be regular (locator)
> > IP address.
>
> I am not sure i understand this clasification.
> Why do you consider that pragmatic identifiers - locators are short lived
> when they are used as identifiers? I mean, i consider that the HoA is a
> stable identifier of the mobile node, but it is short lived as a locator.
>
> I think i can see the difference between a stable identifier and an
> ephemeral identifier, such as the ones used in WIMP, and i think that this
> is usefull distinction.

My comments in the RIPE meeting were drawn from the text I used
in Section 4.7 of draft-huston-multi6-architectures-00.txt, In particular
the last paragraph of that section.

I was struck by the difference between 'absolute' uniqueness (and the 
implication
that when you have such absolute uniqueness you also can support persistence
and reference and resolution) and relative uniqueness (where the identity
uniqueness is constrained temporally to the lifetime of a session (olr group
of sessions) and constrained in terms of a spatial realm, where the possibility
of identity collision  is admitted in a broader context). This 
classification also
has some implications regarding the cost of uniqueness and the relative level
of overhead in managing a long-lived unique token space and opportunistic 
(probably
self-generated) identity token values.

I'm not sure I'm truly in a position to offer comment from my perspective 
as to which is
'better' than the other - there are aspects of value in persistence, 
resolveability and
referential capability in structured unique identity spaces, and there are 
aspects of
value in terms of overhead and efficiency in terms of protocol behaviour
and dependencies as well as reduced dependence on infrastructure activities 
that
paint a value picture for opportunistic identity spaces.

My suspicion that we will need to come to some closure at some point as to
where the ideal point might lie in the context of multi6, and in the 
context of
an evolving IPv6 architecture, but its way to early to call the
question -- in my view. At this stage its still the careful work of 
attempting to
assemble useful characteristics here, so the essential question I have, as 
the draft
author, is where the draft needs further (or less) consideration and text.

thanks,

   Geoff