Annex G and Roaming?

Douglas Clowes dclowes at OZEMAIL.COM.AU
Mon Apr 26 19:00:47 EDT 1999


It all depends on what you mean by "roaming of users between different

Annex G does support some functionality for some favours of roaming, but
requires further development - particularly in how to use these aspects
between domains.

Comments below.
At 14:54 1999-04-23 +0200, Espen Skjæran wrote:
>Hi all,
>I've recently heard (unofficially)  that some claim Annex G
>(APC-1546/TD-20 in Monterey)
>also to support roaming of users between different domains.
>If this is true, I wonder how.
>I can see how the AccessRequest/ValidationRequest might be sent from a
>visiting domain to the home domain for per-call authorization. While
>this might work in simple cases, it will hinder the use of services
>while roaming.

Per call authorization permits a user from one domain to use gateway
equipment from a second domain, to make calls to through a gateway in a
third domain. There could even be a fourth domain present as a clearinghouse.

I don't know what you mean by "hinder the use of services while roaming" in
this context. Perhaps you could elaborate please.

>I can not either see any mechanism to authorize the roaming

Registration is a completely different issue, and I don't see support for
it in Annex G. Perhaps an RRQ with a remote e.164 or IP address could be
issued to the home domain, by the terminal or host gatekeeper?

>I am sorry to post based on "rumors", but this may change the scope of
>Annex G significally, and I worry if this might affect future work on
>roaming. As Tiphon has just started their work on roaming by analysing
>existing roaming techniques in telco and datacom/IETF work,and not yet
>reached any conclusion, it seems premature to use annex G
>in its current state for roaming.

These concepts will have to be developed in parallel. There is more than
one "type" or "roaming", and different people will think of different
things when that word is used. Some people think of terminal mobility,
while others think of mobile IP. Neither of these apply to the mobile user
on public ingress gateways depicted above, but they are no less valid and
need to be considered.

When we know what the opportunities are, we will be better placed to seek
solutions. It is not enough to just say "roaming"!



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