RE : : Using DIAMETER_MISSING_AVP for optional AVP

Hi Mikko,

> > Based on this definition, it is only applicable to AVP
> > "required by the command code definition". It is not clear if
> > we could reuse the same result code for an optional AVP.
> 
> In my opinion here "command code definition" refers to the 
> whole definition of the command, not just the ABNF. Some 
> parts of the definition are often presented in "free" text. 
> For example, Diameter Application command definition might 
> state that Pet-Poodle AVP must be present in the message in 
> case it is Friday the 13th. :)

[LM] Maybe but it is not clear in the RFC3588
 
> > My assumption was that a "SHOULD" was possible here because 
> you could 
> > have relyed on the command code ABNF descritpion to find 
> the missing 
> > AVP.
> 
> So if the command-code ABNF definition defines three required 
> AVPs and you receive DIAMETER_MISSING_AVP without Failed-AVP 
> how do you know which one was missing? You need to know the 
> message contents and the command-code definition (including 
> the rules for "conditional" AVPs) if you want to know what 
> AVP was missing. It doesn't matter at all whether the missing 
> AVP is required or optional.

[LM] Based on the RFC 3588:

6.1.2.  Sending a Request

   When sending a request, originated either locally, or as the result
   of a forwarding or routing operation, the following procedures MUST
   be followed:

   -  the Hop-by-Hop Identifier should be set to a locally unique value

   -  The message should be saved in the list of pending requests.

Receivig DIAMETER_MISSING_AVP without any Failed_AVP AVP, I'm able to
know what AVP is missing just by comparing the pending request with the
command code ABNF description. I don't need extra information if this
error message is only sent for missing "required" AVP.

By the way, this is not a discussion about 'conditional AVPs'. This
concept doesn't exist in the base protocol! We should only deal with
optional AVPs, whatever the use of these optional AVPs.

BR,

Lionel