Mr. Roy & other parties interested in H.323 Annex H,

I found your posting addressing such general level issues that I think it is better to write a whole new mail as a response instead of responding to your claims and comments point by point...

First of all you question the mandate of Annex H and its relation to the H.323 protocols. I find it very odd that you, without any real arguments to support for it, restrict the H.323 recommendations and thus also Annex H to handle ONLY the H.323 entities that have been defined prior to Annex H. The first real work that we got done for Annex H was to identify the functionalities that were (are) needed for Mobility Management and that were missing from H.323. This is how we (in an ad hoc meeting in Red Bank, in which you yourself was also present) came up with the four new H.323 (functional) entities: HLF, VLF, AuF and IWF. Thus we have defined NEW H.323 entities that were NOT present prior to Annex H. If it is illegal for us to define new H.323 entities (as you seem to claim), I can't see how the Border Element ever got defined, since it was not defined prior to the H.225 Annex G.

Second, you seem to have defined the HLF, VLF and AuF as back-end services. This is NOT how I see them. I see back-end services as services that are NOT defined in the H.323 series recommendations, but that may be used by gatekeepers. In other words, back-end services or the functionalities they provide do NOT have any real definition in H.323, nor is it illegal to define new entities to H.323 that provide same kind of functionalities that could be achieved by using some back-end service. The back-end services that are used in some implementations of the H.323 system can undoubtedly be used for similar purposes as the new functional entities of Annex H are, but this does not make the new entities back-end services. Furthermore, the whole point (or mandate) of Annex H is to make recommendations that allow for different manufacturer's equipment to be used in different parts of the (mobility enhanced) H.323 system and still allow the users/terminals to move around in the network. Thus, in my opinion, it is one of the most important issues of Annex H to define, how the HLF, VLF and AuF communicate with each other. By just stating that they are back-end services we would in essence NOT define this, since back-end services are NOT defined in H.323.

Third, the protocol(s) that are used between the HLF, VLF and AuF are still and open issue. The reason, why the H.225 Annex G protocol is used in the present draft is that it is the only protocol that has been seriously mentioned for this purpose. (Not only by the editor, but in various contributions as well, although the editor takes full responsibility of the current text in the draft.) It has been identified that the H.225 Annex H protocol already has the functionality for locating a User with a certain aliasAddress. Really roughly said, this functionality is "half" of the functionality that is needed for Mobility Management, the other half being the location updating procedures (which are not really addressed by the protocol yet). This is why the protocol is being considered for the Annex H usage. However, I would really like to see contributions suggesting other (preferably existing) protocols as well. Intel's contribution APC-1902, was the first one of this kind. These contributions should, however, state clearly how the suggested protocols should be used, if there is any ambiguity. I.e. just stating: "Use Mobile IP" is not enough (I'm not trying to refer to the APC-1902 with this comment), but information flows for the needed Mobility Management procedures should be presented (these include at least the location updating procedures, call establishment procedures, call termination procedures and unregistration procedures).

Fourth, the needed enhancements of the RAS, Q.931, etc. protocols will be provided by finishing the information flows on chapter 10. I admit that not much of this has yet been done, but on the other hand, at least so far I have found that there is not too much that has to be done with respect to these protocols. (There will probably be certain message fields that will be mandatory for Mobile Terminals that are optional in H.323 normally, etc., but I don't see a need for too many new message fields or messages.)

Last, but not least, we a really in a hurry, if we want to get the Annex H determined in November. This is why I suggest that the interested parties provide the contributions describing the usage of other protocols as the Mobility Management protocols of Annex H as soon as possible. Also it would be very nice, if these contributions were made modeling the chapter 10 of the current draft, so that incorporating them to the annex would be as fast as possible.

I'm still a bit in the middle of the process of digesting the information I have gotten about the Annex H work in Portland, but I'll try to send a mail summarizing (what I think is) our current situation later this week (probably on Friday). I will also make a "cleaner" version of the TD-42a as the "starting point" for our interim work before Geneva (this new draft will not contain any other than editorial changes compared to TD-42a).

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

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