Steve,

I that case I look forward to a contribution or more discussion on this reflector regarding problems with the model in which services are executed only in the visited administrative domain.

vineet -----Original Message----- From: Stephen Terrill [mailto:stephen.terrill@ERICSSON.COM] Sent: Friday, April 14, 2000 4:50 AM To: ITU-SG16@mailbag.cps.intel.com Subject: Re: [H.323 Mobility:] questions on MTD-016

Hi Vineet,

I see in your asumptions you have assumed that the services are only executed in the visited network. I donŽt yet agree with that assumptions (that was behind the comments from Nokia towards me as well). You would be aware that we have had significant experience with the model you have presented and would like to see improvements on this model in terms of applying services. The model of "dual service execution" that you proposes has standardisation and deployment issues that we would rather migrate away from.

Regards,

..//steve

"Kumar, Vineet" wrote:

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:

...

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 havenŽt agreed on the role of the VLF, and visited gatekeeper, home gatekeerp and HLF - when we come to agree on what these are, my proposal

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

...

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 preserve

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 the 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

...

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 donŽt 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 the

VLF.

The home gk is not needed. vineet:end

...

Regards, vineet