H.323 Annex I

Edgar Martinez [1] martinze at CIG.MOT.COM
Tue Nov 23 21:36:31 EST 1999


Dear All,

I concur, with most of the attached email.

And I have just a couple of comments. Until we resolve the pure case
of H.323 mobility and  Interworking with PLMN in the application
layer. H.246 Annex I and Annex E will be delayed, I believe that
Annex I and Annex E are depended on H.323 Annex-H. Because,
the required parameters and network functions for the H.323 pure
mobility and Interworking case needs to be defined in H.323
Annex-H. And expanded in H.246 Annex-I and Annex-E.

If we do not get the H.323 mobility and interworking
parameters and functions defined, H.246 annex-i and annex-e
will be working in the dark.

Because of the H.323 framework that we have to use
(already defined e.g., GK, GW, Terminals etc.)
and the already defined mobile networks (e.g., GSM, ANSI-41, GPRS)
we need to  work top-down (not) buttom-up.
Lets focus on H.323 Annex-H to make sure that it has the
network elements that can be re-used in H.246 Annex-I
and Annex-E.

Ed

"Roy, Radhika R, ALARC" wrote:

> Hi, Everyone:
>
> We have now three annexes related to mobility:
> *       H.323 Annex H: User, Service, and Terminal Mobility in H.323
> *       H.323 Annex I: Packet-based Multimedia Telephony over Error Prone
> Channel
> *       H.246 Annex E: Interworking between Existing H.323 Systems and
> Existing Mobile Networks
>
> Per my earlier email, I promised that I would be providing some notes
> related to Annex I: Packet-based Multimedia Telephony over Error Prone
> Channel.
>
> Every Annex in H.323 has some direct relationship to the H.323 application
> layer. Even the informational Appendix II - "Transport Level Resource
> Reservation Procedures" - shows how the RSVP messages are being used in the
> context of H.323 signaling messages.
>
> The way Annex I has been structured shows that it will provide information
> related to bit rate, bit error rate, delay, jitter, and IP issues related to
> radio networks (e.g., mobile IP [home/care-of IP, home/foreign IP network]).
>
> I understand that additional error correction and concealment techniques
> that may help specifically H.323 are the main purpose of this annex. My
> guess is that these proposed concealment techniques will be used somewhere
> below the H.323 layer. If it is so, is not the case that H.323 does not need
> to be aware of these lower layer techniques?
>
> Now the question is: Can this work of Annex I be directly related to the
> H.323 application layer signaling messages?
>
> If the answer is yes, the next question is: Is this present structure of
> Annex I good enough to satisfy our objectives?
>
> If the answer is no, will it be very helpful in H.323 even as informational
> annex?
>
> However, I see that there is an additional scope related to this work of
> Annex I to the H.323 layer signaling messages. IP related issues can be the
> major topic that will really be very useful to relate the network layer
> signaling schemes in mobile environment (e.g., mobile IP) to those of the
> H.323 mobility.
>
> In this context, I see that there are some works that have been performed
> related to the IP networking in mobile environment. It appears that mobile
> IP has some problems: 1. If the mobile host moves very frequently and 2.
> Inefficiency for keeping too many reserved IP addresses in the pool by the
> foreign agent for allocation to mobile hosts.
>
> To work around those problems, there has been enhancement of mobile IP
> (e.g., cellular IP) complementing the mobile IP solution.
>
> The important point is that they have been using the concept of cells, cell
> IDs, and network IDs packet-switched based IP mobile networking environment.
> A cell can be pico-, micro-, and macro-cell depending on the radio range
> which is a function of power. Cells are usually inter-connected by the LAN
> in the case of IP networking.
>
> (By the way, none has used the concept of so-called location area [LA]
> concept in the IP networking either in the mobile IP or in the cellular IP.
> I am curious to know why these prototype products and network architectures
> do not contain the concept of LA? Can anyone provide more insights about
> this? Personally, I would love to relate the LAs with cells. Indirectly, it
> may also help to inter-work with that of the circuit-switched based
> cellular-PSTN network.)
>
> The important point is that we can start with the existing standard of
> IETF's mobile IP/cellular IP. We can see that switching a cell during
> communications does not always mean changes in IP addresses. That is, this
> handover (at layer 2) may be transparent to the IP network layer (layer 3).
> No resources in the IP layer will be affected. If the switching in cells
> causes the change in the IP address during communications, the handoff will
> cause the resource allocation and de-allocation in the IP layer during and
> after handoffs.
>
> Extending the same analogy, we can assume that switching of the cell may or
> may not cause any change in the H.323 application layer. If it affects the
> H.323 layer, the resources in the H.323 layer have to be allocated and
> de-allocated in the H.323 layer during and after the handoff.
>
> The other important concept is that the cell IDs can also be related to
> H.323 zone IDs and so on.
>
> It appears that the mobility solution can be related to the link layer
> (layer 2) to the network layer (IP layer) mobility and the H.323 application
> layer and vice versa. As a test case, people may also try to see how the
> application layer H.323 mobility solution (e.g., APC-1651, APC-1646) can be
> implemented to the network/link layer mobile/cellular IP solution
>
> In this way, I see a wonderful ray of light how the work of Annex I can be
> related to that of Annex H.
>
> Last of all, I would request the editor to expand the scope Annex I. If
> needed, I may also propose to include this item in the upcoming/future
> conference call.
>
> In the same token, I may also provide some comments related to H.246 Annex E
> in the future.
>
> I would request all SG16 members to look into this proposal and help us with
> their comments.
>
> Best regards,
> Radhika R. Roy
> H.323 Ad Hoc Mobility Group
> AT&T
> +1 732 420 1580
> rrroy at att.com

--
Edgar Martinez - Principal Staff Engineer
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