Subject: RE: [Dime] Summary of 3588bis Issues Status

From: "STURA, Marco, VF-IT" <[email-masked]>
Date: Tue, 18 Jul 2006 17:25:49 +0200

>It maybe a little bit confusing for relays with cannot resolve a route via >destination-host to look at an ASR with an app id of 0.

Interesting argument I have to say. Routing ASR based on app id doesn't ensure that the session ASR is supposed to kill is actually running on the client where the request is routed to. Suppose a relay agent connected to 10 clients all of which support app id x, the relay routes based on app id x to client 2 but the session indicated in the <session-id> is actually running in client 5. The ASR will not kill the session as requested by the server, therefore ASR MUST use Destination-Host based routing.

Same argument stands for RAR.

In fact the base defines ASR and RAR with Destination-Host AVP as mandatory in the ABNF of the message.

I think in the AAA thread also available in the issue tracker there were arguments why ASR is really a common message, same would be for RAR if no mandatory AVPs are defined by the application.

Regards
Marco

-----Original Message-----
From: Victor Fajardo [mailto:[email-masked]] 
Sent: martedì 18 luglio 2006 16.53
To: STURA, Marco, VF-IT
Cc: [email-masked]
Subject: Re: [Dime] Summary of 3588bis Issues Status

Hi Marco,

The main reason (and people can correct me if i'm wrong) is that these 
messages belong to the session/application using them and it is 
better/easier to co-relate these messages to the said application. Since 
the base protocol really defines two sets of messages, one set is for 
session/application usage and another for peer connectivity, it is also 
semantically correct for the the session message to carry the app id of 
the session.

In addition, for implementations, it is more practical to look at the 
app id in the header to determine the application that a message belongs 
to ... and rightfully so. In my opinion, ASR belongs to this category 
even if it is server directed. It maybe a little bit confusing for 
relays with cannot resolve a route via destination-host to look at an 
ASR with an app id of 0.

hope this helps,
victor
> Hi Victor,
>
>   
>> This topic is issue #2&5 and refers to what app id 
>> should "application session level" messages defined in the base
>>     
> protocol 
>   
>> (STR/STA, ASR/ASA, RAR/RAA, ACR/ACA) use. The current consensus in the 
>> meeting and more likely in this list as well is that it MUST carry the 
>> app id of the application using it.
>>     
>
> Could you bring some light on the reasons behind this consensus? I
> thought the discussion in the old AAA list was toward a consensus on
> using Appl ID 0 at least for the ASR/ASA Diameter common messages.
>
> Regards
> Marco
>
>
>
>
>   

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---

From: Victor Fajardo <[email-masked]>
Date: Tue, 18 Jul 2006 12:09:33 -0400

Hi Marco,

> Interesting argument I have to say. Routing ASR based on app id doesn't ensure that the session ASR is supposed to kill is actually running on the client where the request is routed to. Suppose a r…

I agree with your example above regarding destination-host. It is 
required in the case of ASR (and perhaps some other message) though I 
guess I was stating a case which is a little bit different than your 
example above. I was thinking of the following case:

clients[1,2,3...x] <--- relay1 <---- relay2 <---- server

in this case relay2 will not be able to route using dest-host. This is 
where dest-realm and app id becomes important. In this case app id of 0 
might not work as well ... or maybe I'm wrong.

> I think in the AAA thread also available in the issue tracker there were arguments why ASR is really a common message, same would be for RAR if no mandatory AVPs are defined by the application.
I've read through some of the comments in the AAA thread regarding this 
issue and it was not clear to me why an app id of 0 is applicable to ASR 
and/or RAR. In fact, in diameter CC (rfc4006) the app id of RAR is set 
to 4 (CC app id).

hope this helps,
victor