Hi all,

Maybe I should first clear up a potential misunderstanding. I don't think anyone in the Mobility ad hoc group is trying to avoid taking the work done in IMT-2000 or 3GPP into account.

In fact we have used the IMT-2000 specification in our work already quite a lot (it is not a coincidence that the requirements, etc. are so similar between H.323 Annex H and IMT-2000) and definitely we would like to follow the IMT-2000 framework as much as we see possible (further co-operation and meetings would certainly be a positive thing). Also I am currently working on making the terminology of Annex H to correspond better to the 3GPP terminology as was requested in the Portland meeting. Furthermore, one of my intentions when encouraging people to come up with contributions for the Mobility Management procedures (information flows) of the annex has been to get propositions that might be better in line with especially the 3GPP work. Unfortunately I feel that I myself am not yet enough of an expert in 3GPP issues to be able to do that.

However, I think the general feeling in the ad hoc group has been that the 3GPP and IMT-2000 specifications on the Mobility Management procedures will still take quite long before being ready. Another issue that has been raised is the question of possible (or probable) unnecessary complexity of the coming 3G Mobility Management protocols for enterprise usage. Thus a need to specify simple procedures for the Mobility Management quite quickly for H.323 has been recognized and this would also necessitate the definition of protocols or specifying how existing protocols would be used between the VLFs and HLFs for instance.

In the absense of propositions to use other existing or future protocols, the annex draft at the moment suggests the usage of somewhat altered H.225 Annex G protocol as the Mobility Management protocol to be used between the GKs, VLFs, HLFs and AuFs (I think we should also limit the interfaces we are defining for the first version of the annex to perhaps just handle the VLF-HLF communications...). The good thing about this approach would, at least, be the easy addition to already existing H.323 systems because of the usage of existing (albeit slightly altered) H.323 family protocol.

------------------------------------------------ Jaakko Sundquist * +358 50 3598281 * Audere est Facere! jaakko.sundquist@nokia.com * ------------------------------------------------

Hi, Everyone:

Sorry for not getting into the discussion earlier since I was out of station for some time. I just logged into my PC and saw your interesting e-mail discussion on mobility management protocols (in particular between the VLF and HLF).

I would like to share here some concerns of Radhika Roy on this matter. As he clearly points out, the HLF and VLF are only value-added functions which are necessary for handling mobility of users. There is nothing specific in VLF <-> HLF in terms of mobility with respect packet vs. circuit or connection oriented vs connectionless, etc.

As you are probably aware of, the IMT-2000 group in ITU-T SG11 is currently working on developing a common mobility management protocol which should accomodate various users of different types of mobile systems (e.g. IS-41, UMTS, etc). This is the well known FAMILY concept in ITU-T SG11. SG16 and SG11 had one joint meeting in the last Feb'00 in Geneva. During this meeting, this mobility protocol work was briefly introduced by SG 11 and it was recognized that the requirements & major concepts identified for mobility in H.323 networks are very similar to those of IMT-2000 (since IMT-2000 should also provide packet-based multi-media services), and a close cooperation between these two groups is required on mobility and roaming aspects for the benefits of H.323 and IMT-2000 systems. In addition, this will allow the roaming of any users between different types of network (for instance an H.323 user roaming into an IS-41 or UMTS network and vice-versa). Therefore, I tend to disagree with Jaakko who says that IMT-2000 is not defining (or intended for) packet-based networks. For instance the concept of VLF and HLF are pretty much close to those of the LMFv and LMFh in IMT-2000 (see ITU-T Rec. Q.1711) for the strict reason that they are both server functions which handle mobility independently of the transport networks. Then why not a common protocol for common mobility requirements and functions? On the other hand, I agree that Extensions of H.323 (e.g. H.225.0 [RAS, Q.931, Annex G]) need to be provided by Q.13/16 since they are very specific to the H.323 type of access.

Again, I would like to support Radhika in his analysis of trying to develop a common solution that fits the need of any type of mobile users rather than developing one VLF <-> HLF protocol for H.323, one VLF <-> HLF for H.321, etc. Otherwise, it will be a BIG mess for network operators (as well for manufacturers) and lead to have different protocols which may be incompatible between themselves. This will also make the inter-networking aspects very tough thereby preventing any global roaming of users.

FYI, I would also like to inform you that 3GPP has selected SIP for its MULTIMEDIA stuff. In this case, how would it be possible to roam between a 3GPP network and H.323 network, and with other networks (not using SIP)unless an inter-connecting pipe such as a common MM protocol (which includes SIP mobility, H.323 mobility, IS-41 mobility, etc) is developed.

Therefore, I would suggest that we should rather work with a more global picture of ITU (as supported by Radhika) than a narrow one limited to H.323 mobility only.

Let me be more positive now. I would really encourage SG16 and SG11 to closely cooperate together in order to develop this common protocol jointly for the success of ITU. I believe that this step has already started at the joint SG16-SG11 meeting in February 00. Why shoudn't this be continued?

Best regards,

Jean-Claude Samou, PhD France Telecom R&D 38-40, rue du General Leclerc 92131 Issy les moulineaux France

Tel: + 33 1 45 29 58 40 Fax: + 33 1 46 29 31 62

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