Hi, Steve:

In H.323, GKs are the communication entities thorough which registration and other services are obtained by users while VLFs and HLFs are used ad databases to store the information that are appropriate related to the mobility management.

In H.323, a user is always associated with a GK through registration, and a GK manages a zone where all its H.323 registered users reside. In addition, a GK also manages resources of the zone.

Please also see the mobility management information flows in AT&T contributions MD-017 and MD-018 how the GK is involved to resolve information via VLF and HLF.

A mobile user MAY like to differentiate between a home GK and a foreign GK (security and many other reasons). It is an OPTION, not mandatory.

Hope this clarifies your questions.

Best regards, Radhika

-----Original Message----- From: Stephen Terrill [mailto:stephen.terrill@ERICSSON.COM] Sent: Friday, April 14, 2000 8:02 AM To: ITU-SG16@MAILBAG.INTEL.COM Subject: Re: [H.323 Mobility:] questions on MTD-016

Hi Roy,

Can you please clarify why the gatekeeper selected for the services is a "user" issue?

Regards,

..//steve

"Roy, Radhika R, ALARC" wrote:

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Hi, Vineet and Steve:

I like to add couple of points with respects to your emails as follows:

HLF:

It is interesting to note that there appears to be an "implicit" assumption that there is only one HLF in a domain (no matter what happens in the future).

Let us NOT make our protocol "hard-wired" like this.

The protocol should be flexible enough to accommodate one or multiple HLFs in a domain.

If one wants to choose one HLF per domain, it MUST be left as an implementation issue, NOT a protocol issue.

Home GK:

In the same token, if one wants to declare a GK as its home GK, this option MUST be provided to a user. It is a choice that MUST be given to a user. If anyone does NOT like this option, they MAY not use it.

Home Network/Network Address:

In the same token, if anyone wants to declare a network address as its home network, this option MUST also be provided.

GK Discovery:

The "old" inefficient GRQ discovery mechanisms may not be the only OPTION to discover the GK. in a highly mobile cellular environment. An alternative mechanism, like MGA message can be listened to discover the GK as well.

Best regards, Radhika R. Roy

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-----Original Message----- From: Kumar, Vineet [SMTP:vineet.kumar@INTEL.COM] Sent: Thursday, April 13, 2000 4:34 PM To: ITU-SG16@MAILBAG.INTEL.COM Subject: Re: [H.323 Mobility:] questions on MTD-016

Steve,

Thanks for your reply. My comments are embedded in the email below.

vineet

-----Original Message----- From: Stephen Terrill [mailto:stephen.terrill@ERICSSON.COM] Sent: Thursday, April 13, 2000 4:42 AM To: ITU-SG16@MAILBAG.INTEL.COM Subject: Re: [H.323 Mobility:] questions on MTD-016

Hi,

I shall try to answer some of these questions below.

Regards,

..//steve

"Kumar, Vineet" wrote:

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Stephen,

I have a couple of questions on your contribution MTD-016. These are:

1. H.323 already has mechanisms for discovering the gatekeeper. Are you suggesting in your contribution that the terminal should discover the VLF instead of the visiting gatekeeper ? Or, are you assuming that the VLF is integrated in the visiting gatekeeper ?

This can be discussed - I was of the opionion that we should discover the VLF and send the registration to the home environment after that. However, we haven´t agreed on the role of the VLF, and visited gatekeeper, home gatekeerp and HLF - when we come to agree on what these are, my

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may change.

<vineet:begin> Yes, this could be discussed in the conference call. My suggestion is to reinvent as less as possible. Since we are adding Mobility to H.323, we should just fill in the gaps that are missing. <vineet:end>

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2. In H.323, authentication of the terminal and the gatekeeper is

done at the time of discovery. In fact, in H.323 all messages between the terminal and the gatekeeper can be authenticated and the message integrity preserved. In your contribution, authentication is done at the time of registration. Why is this preferable to what is already in H.323 ?

I would be interested to understand which gatekeeper you were considering should do the authentication. I would assume that the real authentication would have to be done at home - as such it would be necessary to find the visited network services, and then register/authenticate at home.

<vineet:begin> I agree with your model but my preference is to

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the way H.323 works today in that the authentication of both the user (not terminal) and the gatekeeper (doesn't matter whether the gk is visisted or home) can be done at the time of discovery. The protocol between the terminal and the gk does not change regardless of whether it is the home gk or the visited gk. The terminal sends its hashed password or certificate in the cryptotoken field of the GRQ message. The visisted gk tunnels the entire message to the terminal's Home Administrative Domain for authentication and authorization. There may be an Authentication Function in the Home Administrative Domain that authenticates its users. If the user is successfully authenticated by the Home Administrative Domain then a new temporary password is assigned by the Home Administrative Domain to

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terminal and the visited gk in GCF for use during that session. This exchange is explained in detail in the contribution I made for the last conference call. I can't find the MD #. Does anyone know the MD # ? <vineet:end>

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3. What is the reason for the information flow from the HLF to the

home gatekeeper, and from the home gatekeeperr to the HLF ? I don't think we can assume that there is only one home gatekeeper that the terminal may be using. In fact, the home gatekeeper may not have any information about the user.

I certainly don´t assume that there is only one home gatekeeper. I assume that there will be a number of home gatekeepers, but perhaps only one (or few) HLFs. In this case, we need an function to select the gatekeeper that the user is going to camp on - and this may depend on load, subscriber profile, policy - or a lot of things.

<vineet:begin> I guess I will have to understand the model that you have in mind regarding the use of a home gk on which the terminal camps on. In my model the HLF will send all pertinent information about its user to

Hi, Steve: I guess that you did not get my point exactly. It is NOT exactly where the "service" to be executed. It is user's choice whether certain things to could be perfumed as their choices (for example not to reveal addresses while NOT moving - for example mobile IP permits) etc. Now where the service to be permitted, we may have another debate. There should be flexibility: Home Domain vs Foreign Domain and other criteria. As I explained earlier, what is meant by network in H.323. Please see the email sent in response to Jaakko's. I would be pleases to explain in terms of home/foreign (visiting/visited/target) domain/zone/network address. For the role of the GK in H.323 is clear. There is no ambiguity. Please see my email that will be sent very shortly. Please also see email that will be shortly how we can reconcile all contributions together describing the role of GKs, HLFs, and VLFs: AT&T, Alcatel and yours (Ericsson). Best regards, Radhika R. Roy AT&T -----Original Message----- From: Stephen Terrill [mailto:stephen.terrill@ericsson.com] Sent: Sunday, April 16, 2000 5:11 AM To: ITU-SG16@MAILBAG.INTEL.COM Subject: Re: [H.323 Mobility:] questions on MTD-016 Hi Roy, I still don´t understand why it is a "users" choice where the "services" are executed - I would have thought that this would be networks choice - and the means for doing that is what we are now discussing. Can you please clarify why a user "MAY" which to decieded this. One thing that is now clear is that there are different expectations of the roles of the gatekeepers, VLFs, HLFs etc expressed amongst the participants of the list - and this has to be clarified. Regards, ..//steve "Roy, Radhika R, ALARC" wrote: proposal preserve the the

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VLF. The home gk is not needed. <vineet:end>

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Regards, vineet