H323mobility: meeting

jaakko.sundquist at NOKIA.COM jaakko.sundquist at NOKIA.COM
Tue Nov 2 11:13:07 EST 1999

                Once again, hi, Radhika, Ed + all

                See my comments below...

                Hi, Jaakko, Ed, and All:

                I hope that Jaakko will get this mail while he is in his
office (Thanks
                Jaakko - you have reminded us the time difference)!

                [Jaakko:] You caught me just in time.

                Please note the following:

                1. Zone and domain are well defined in H.323.
                [Jaakko:] Yes, they are defined.

                2. We have to work for mobility solution in a way that fits
very well that
                already exists in H.323.

                [Jaakko:] Agreed.

                3. We can invent many things if we need to solve mobility
problems only when
                we think that those functions are NOT covered in existing
H.323 standard.

                [Jaakko:] Yes.

                4. If mobility problems can be solved using the concept of
"zones" and
                "domains," I would assume that it would be a big mile stone
so far the
                continuity of H.323 is concerned. That is, as Ed pointed
out, H.323 mobility
                problem is NOT a rocket science. We have to remember that we
are working in
                the framework of already existing H.323 standard
architecture. We have to
                relate our solution in the context of existing H.323
standard. In other
                words, we CANNOT change the fundamental concept of existing
H.323 standards
                just because we are addressing mobility.

                [Jaakko:] Yes, of course. I'm not arguing against that. I
guess you are referring to the Location Area discussion here. The LA concept
is really merely a scaling issue, you could of course handle paging (I'm
assuming that we will need the paging procedure) based on zones, i.e. page
every NPoA in a zone when a call arrives, but this might be quite limiting
in some cases (the zone may be needlessly big or very small). I do not think
that we need to change any fundamental concepts of H.323, if we introduce
the LA concept.

                5. I do not understand what benefits we are gaining adding
                "terminologies" like "AREA {home, foreign, etc}" while the
"zone" and
                "domain" are already well defined in H.323. My personal view
is that we
                should FIRST try to solve H.323 mobility problems within the
context of
                "zone" and "domain" as far as practicable. I would argue
that zone and
                domain are good enough to serve this purpose for now. (Pl.
also see AT&T's
                and Motorola's contributions.)

                [Jaakko:] As I already said, I did not intent to define the
terms: home area and visited area. I was just trying to illustrate the point
I was making about not having the Home/visited zone terms defined yet.

                6. With respect to your comments that it appears that every
GK will have HLF
                and VLF function, I would say that every GK will have the
access to the HLF
                and VLF function. This capability for each GK has to be
provided because of
                the fact that H.323 architecture is GK-centric. We do not
have any choice
                because we are restricted by the H.323 architecture.

                [Jaakko:] I did not argue against this. The point is that if
we identify a concept called the Home Zone, this already implies that each
User has only one zone, in which he/she/it is not a "visiting user". I think
this would be really restricting.

                6.1 With respect to your question whether HLF/VLF can be
distributive or
                centralized, having said (in item 5) that every GK should
have access to HLF
                and VLF function, it is up to implementation whether HLF and
VLF function
                can be centralized or distributive. Please see AT&T
contributions submitted
                in Red Bank how we can implement these functions in both
distributive and
                centralized environment.

                [Jaakko:] This is actually quite much the point I was
making. By defining the Home Zone we would in my mind actually be pointing
to the centralized model.

                6.2 In an analogy of this HLF/VLF function, I can bring
another function -
                Directory services. For example, H.323 assumes that all the
address (e.g.,
                alias, transport, network) are kept by each GK. H.323 does
not answer how
                the address information is maintained by each GK. People are
using LDAP
                directory server. The question is: whether that directory
service is
                distributive or centralized? I guess that it can be done in
both ways
                depending on implementation.

                [Jaakko:] My point exactly. I would like that all GKs inside
the same Administrative Domain would be able to access the same HLF/VLF

                6.3 In AT&T contribution, it is shown that it better to make
                distributive (per GK) although HLF function can be made both
                and centralized. Again, this is a matter of implementation.
As mentioned in
                AT&T contribution, we also need to define a kind of backend
protocol for VLF
                and HLF (something like similar to Siemens, Nokia and
Intel's contribution -
                TD-39: Security Services for Backend Services and Mobility
in H.323).

                [Jaakko:] I would assume that you can distribute the HLF/VLF
functionalities inside the Administrative Domain as you like, but
distributing them between the Domains would be difficult. Actually I think
that the concept of Administrative Domain was introduced in H.323 for this
kind of reasons.

                7. Again, I, personally, do not rule our to re-examine the
benfit of "AREA"
                (e.g. location area [LA]) vs. "ZONE/DOMAIN" concept. May be
it is in the
                second step.

                [Jaakko:] I am just a bit afraid that if we leave this kind
of a major mobility related concept out of the first phase thinking process,
we will find it much more difficult to include the concept in the second
phase (where I think we will need it). Furthermore, I'm not convinced that
the LA concept would not be useful in the pure H.323 approach either.

                Hope that this email will clarify the things better.

                [Jaakko:] I think the main thing is that we got the
discussion going on again. I'm kind of tired already, and I hope that I
didn't mess things up too much in this mail.

                Best regards,

                Same to you,

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