Subject: [Pana] the question that I wanted to ask at the mike before the line was cut off...

From: Jari Arkko <[email-masked]>
Date: Mon, 01 Mar 2004 09:20:38 +0200

I guess I still don't understand how roaming works in PANA.
Currently, Diameter, for instance, works through looking at
the NAI at the NAS, and placing this value in the Destination-Realm
AVP. All this happens in the NAS. But the NAS doesn't have
to have all routing information to the possible realms. Instead,
it would typically have a default router to the access provider's
proxy or mediating network's proxy which makes the final routing
selection.

This is simple enough so far, but what's the problem with PANA?
The issue is that I don't understand how you can use the ISP-Information
at the PANA layer to fill in the Destination-Realm. Or you can use
it in the case that the NAS has been configured to recognize the
given ISP. But in a typical case the NAS would not be configured with
the 1000 different home realms that you can be connected to. So,
does PANA limit selected ISP to the ones it has advertised? If yes,
then you would have to have all those 1000 ISPs configured in the
PANA-enabled NASes. If you try to force one of the few known ISPs
(bighome.com) but the user wanted to get to another one
(smallandunknownisp.com), things would break, I think. This is because
the Destination-Realm would be set to bighome.com whereas you really
should have set it to smallandunknownisp.com. In either case the message
should be directly sent to the bighome.com AAA server, but this can
only route the request further if the Destination-Realm AVP is
set correctly.

--Jari

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From: Alper Yegin <[email-masked]>
Date: Mon, 01 Mar 2004 18:01:51 -0800

> given ISP. 

The NAS (PAA) should already be configured to advertise the ISP-info. 
Destination realm can be stored as an attribute of each ISP.

> But in a typical case the NAS would not be configured with
> PANA-enabled NASes. 

Dealing with so many ISPs might be hard. In that case, the deployment
might choose to rely on NAI-based selection (and no ISP advertisements).

Btw, even if the PAA advertises a list of ISPs, PaC may not send an
ISP-info back and instead expect the selection be made based on its NAI.

We haven't thought whether the advertised ISP list should be considered
an exclusive list. I guess we can go either way with the design. Or,
even have a flag that indicates whether the list is exclusive or not.

Alper

> If you try to force one of the few known ISPs

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From: Jari Arkko <[email-masked]>
Date: Tue, 02 Mar 2004 04:03:37 +0200

> ISP-info back and instead expect the selection be made based on its NAI.

This would be sufficient to handle the very many ISPs case, I think.

--Jari

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From: Alper Yegin <[email-masked]>
Date: Mon, 01 Mar 2004 18:01:51 -0800

Alper

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From: Jari Arkko <[email-masked]>
Date: Tue, 02 Mar 2004 04:03:37 +0200

--Jari