Subject: RE: [AAA-WG]: One basic question

From: "Li Chunan (Nokia-RD/Beijing)" <[email-masked]>
Date: Wed, 16 Jan 2002 17:19:54 +0800

Hi

That's a good question. If the AVP data type is known in advance, it
will be helpful to save and access the AVP data in real Diameter
implementation.

B.R.

Li ChunAn
----------------------------------------------------
Advanced Internet Technologies Group
Communication Systems Laboratory
Nokia Research Center
No.11, Hepingli Dongjie, Beijing, 100013
Email: [email-masked]
MP: +86 13601028331

-----Original Message-----
From: ext Ghadiyaram Venkata (EXT-TataConsultancy/Helsinki) 
Sent: Wednesday, January 16, 2002 4:31 PM
To: [email-masked]
Subject: [AAA-WG]: One basic question

Hi,

I have one question out of curiosity. 

What if the AVP header also contains the data type information? 

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           AVP Code                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |V M P D r r r r|                  AVP Length                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Vendor-ID (opt)                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        DataType code                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Data ...
                +-+-+-+-+-+-+-+-+

DataType code - The code representing the data type. 
D flag - Tells wheher the data type is vendor specific or not.

I feel that this reduces a lot of overhead on the implementations. Any
comments...

Is this already considered previously. If yes, why is it rejected. 

Thanks and regards,
Kishore

---

From: David Frascone <[email-masked]>
Date: Wed, 16 Jan 2002 08:26:05 -0600

But, then why have a dictionary at all.  What could you do with a type that
you couldn't do with the AVP code?

I mean, let's say you get an unknown AVP, where the data type tells you
it's an OctetString.  Now what do you have that you didn't have before?

I suppose you could have better debugging information i.e.: "Received
unknown AVP 0x29485 Value:"qwerty"  But, I don't see that it adds any 
additional functionality to the protocol itself.

So, I'm against this change.

-Dave

---

From: Erik Guttman <[email-masked]>
Date: Wed, 16 Jan 2002 16:57:53 +0100 (MET)

Kishore,

> What if the AVP header also contains the data type information? 

An AVP is an attribute value pair.   The attribute is identified
by an ID.  If you recognize the ID, you know what type it has.
If you do not recognize it, you know the length of the AVP and
may skip it.  

Explicit type fields in protocols yield limited benefit.  ASN1
vs. non-ASN1 debates are boring - let's not have one here.

Erik