Thank you all for your comments.

Roelands Marc wrote:

Hi all,

I am struggling with some conceptual problems concerning the Annex-H proposal of Edgar Martinez, feeling that this has some commonality with the remarks of Roberto Winkler and Simon Binar on it. IMHO, the proposed architecture, and especially the WAU and the GK, are mixing all kinds of mobility related functionality in a single, strongly coupled, do-it-all-in-H.323 layer, involving radio access up to H.323 application layer.

I believe there is a clear separation of functional requirements between the radio control functions of the WAU, and the Network control and Mobility Management functions in the GK. Would it make everyone happy if we called WAU RAN? For network efficiency the WAU would handle all the Radio link resources at the edges, thereby preventing traffic overloading on the network.

Specifically, I have some difficulties with the following:

1. No clear division in terminal and user mobility aspects in the basic

H.323 architecture is taken as a starting point: shouldn't there be specified somewhere in general, in conjunction with the H.323 set of protocols, that IP addresses represent terminals in an IP network, and that users can only be represented by logical names from a directory (i.e. aliases), and whether an "endpoint" is a user or a terminal? If this is decided on, the H.323 registration procedure is just what is needed to have user mobility, by dynamically associating a logical user name with one or multiple terminals upon user request. With terminals identified by IP addresses, terminal mobility would further be strictly a network access problem.

2. Annex-H is supposed to handle user and service mobility, so why would the

handover problem, as any other terminal mobility related problem, be handled here instead of independently in Annex-I?

In the second day of the Ad-hoc SG-16 meeting, some of us discussed, the possibility of combining Annex H and I, if no contributions came in for Annex-I.

3. Mobility is not an issue in H.323 alone, e.g. consider roaming and

handover for a connection-oriented data application, so why should it be handled in H.323 on its own? Or put otherwise, is H.323 support really required on a terminal in order to be able to roam, as a user of some service, or as a terminal accessing a network?

I specifically asked where do we focus, and was told to assume that there will be H.323 wireless sets. And focus only on H.323 terminals, to get the work started. And that other types of terminals would be handled separately.

4. Although the proposal pays attention to the identification of several

degrees of locality for roaming and handover, solving all control issues (radio access, IP-networking, etc.) in a single application layer still leads to both resource sub-optimality and complexity. E.g. why should the WAU be aware of anything having to do with (user) mobility management?

I believe there is a misunderstanding the mobility management and services is handle by in the network e.g, GK. The Radio Resource management is at the edges which is aware of the terminals radio links.

Instead I would propose to use an approach of highly independent layers, following good Internet tradition, and solving the problems as locally as possible (both geographically and architecturally). Here's the layers I think at least should be distinguished:

• MAC level: terminal micro-mobility across radio cells, ethernet segments,

etc. can exist without any consciousness of this at the IP level (e.g. using wireless LAN tunneling techniques);

• IP network level: terminal macro-mobility across the Internet should be

invisible to higher layers (e.g. by means of Mobile IP v4 or v6 and the improvements suggested for delay-sensitive traffic like RTP streams: Mobile IP HAWAII, or draft-elmalki-mobileip-fast-handoffs-01 to name but a few; note that route optimization is also worked on in this area);

• "terminal real-time signaling" application level: the level where

telephony and MM signaling like H.323 can be placed (restricting GW and GK functionality to strictly this level); here Annex-H might define transport for additional parameters and vertical signaling, useful for serving the "user services" application level (below); at this lowest application level packet to circuit switched network boundaries may be crossed (cf. the evolving traditional telephony networks vs. the Internet);

• "user services" application level: user and service mobility takes place

here, making use of a network- (and H.323) independent naming system (directories using e.g. DNS, LDAP schemas, etc.) and e.g. back-end services, "behind" or "on top of" one or several GKs for realizing UM, user mobility support for a larger scope than just H.323, smart user assistance, etc..

This approach has not only the general advantage that every layer can evolve technically independent of all others, it also has the specific advantage that it realizes true consolidation of mobility for telephony and traditional data applications.

As a last point, it is not clear to me at which of these levels H.450 would belong. As it is specified now it is on top of H.323, but suppose one would like to adopt a service provision model where a user could subscribe to a telephony-related service , wouldn't it be nice then to be able to offer this across different telephony technologies (a bit like where IN aims at)? A comparison to using a HTTP service control layer (Annex-K) might be interesting here.

I cannot imagine that these fundamental issues where not previously discussed in ITU-T SG16 or Tiphon WG7, so if anyone can give me some arguments why an approach as I tried to describe here could not be followed, I would be glad to know about it.

Your comments are very good and your suggestions are very applicable to what we are working on, but unless a contribution is presented to the proper groups e.g., ITS-sg16 q13/14 they would just fade away. ITU recommendations are contribution driven.

Best Reagrds, Ed

Regards, Marc Roelands Siemens ICN Atea Atealaan 34 B-2200 Herentals Belgium Tel.: +32 14253965 Fax: +32 14222994 E-mail: marc.roelands@siemens.atea.be

-----Original Message----- From: Roberto Winkler [mailto:wnk@FUB.IT] Sent: Tuesday, September 14, 1999 10:34 AM To: TIPHON_WG7@LIST.ETSI.FR Subject: Re: [Fwd: Re: [Fwd: [Fwd: [Fwd: Re: H.323 mobility first darft]]]]

Jin, Edgar,

If I may try to give my 2 cents in this discussion, I think that the problems/weakness of 3GPP considered systems (which Edgar is speaking about) cannot match with the faults identified by Lucent's contribution, which is focused on the unique issue of R99 terminal support in the All IP R00 network. Considering these 3GPP contributions does not help in understanding Edgar's point of view. I have already sent a few e-mails to comment the proposed mobile H.323 architecture and would like to summarize here my view, hoping to get reactions:

• the role and reason for being of WAU is unclear (as TIPHON is focused on

user and service mobility, why worry about the access medium ?)

• the redefinition of several RAS channel messages is confusing (why does

the RAS channel terminates at WAU ?)

• protocol stacks and interface definitions are missing from the picture.

best regards

-- Edgar Martinez - Principal Staff Engineer Email mailto:martinze@cig.mot.com FAX 1-847-632-3145 - - Voice 1-847-632-5278 1501 West Shure Drive, Arlington Hgts. IL 60004 Public: TIPHON & Other Stds - http://people.itu.int/~emartine/ Private:TIPHON & Other Stds - http://www.cig.mot.com/~martinze/