Re: : ISSUE: Sections 4 & 5.10 appear to contradict each other

Glen Zorn (gwz) wrote:

> Miguel Garcia <mailto:[email protected]> supposedly scribbled:
> 
> 
>>Glen Zorn (gwz) wrote:
>>
>>
>>>Description of issue: Self-contradictory text Submitter name: Glen
>>>Zorn Submitter email address: [email protected] Date first submitted: 17
>>>Oct 05 Document: sip
>>>Comment type: T
>>>Priority: S
>>>Sections: 4, 5.10
>>>Rationale/Explanation of issue: Sections 4 & 5.10 appear to
>>>contradict each other: Section 4 says "Central to the architecture
>>>is the fact that the user data is stored in a single point in the
>>>network.  This restriction does not mandate a particular
>>>implementation, e.g., it is possible to implement clusters of
>>>databases operating in mirror mode to provide redundancy.  The
>>>property required by this specification is that the user data the
>>>Diameter Server has access to is stored safely in what is seen, from
>>>the external point of view, as a single user database", but section
>>>5.10 says (in describing the process of finding the correct Diameter
>>>server) "The Diameter SL, based on the contents of the SIP-AOR AVP
>>>and its own routing tables, determines the Diameter server that
>>>stores the information allocated to such user.  Then it builds a
>>>Diameter LIA message (step 3) that includes a Result-Code AVP set to
>>>DIAMETER_REDIRECT_INDICATION and one or more Redirect-Host AVPs,
>>>whose values are set to one or more URIs of Diameter servers that
>>>store the information related to such user.  Then the Diameter
>>>client in SIP server 1 builds a new LIR message (step 4) addressed
>>>to any of the Diameter servers received in the Redirect-Host AVPs". 
>>>It seems to me that either there is exactly one Diameter server that
>>>stores data pertaining to a given user or there is more than one. 
>>>
>>>Requested change: Make the document consistent; how this is done is
>>>up to the authors. 
>>>
>>
>>I think you didn't read carefully, because I don't find the
>>contradiction. 
> 
> 
> OK, I'll try again: "one" != "one or more".

Ok, I understand now your concern. So you are saying that, because the 
data is stored in a single server, there should be exactly one 
Redirect-Host AVP in the LIA command.

Initially I agreed... but then I check RFC 3588, and it allows to have 
multiple Redirect-Host AVPs. It actually says that the client selects 
one entry.

I think that one could have a list of Diameter URIs in the Redirect-Host 
AVP. This enables to indicate "please select any of the n equivalent 
diameter servers" (that are configured with synchronized data).

One can argue that we can do the same with DNS round robin and a single 
Diameter URI, which is true. The question is whether we want to put an 
artificial limit here or not.

In other words: both the current specification and your proposal work. 
The current specification can accommmodate more use cases in my opinion, 
but if it is misleading, we can change it.




> 
> ...
> 
> 
>>With this in mind, please propose text if something has to be
>>clarified. 
> 
> 
> OK, here: change "The Diameter SL, based on the contents of the SIP-AOR AVP
> and its own routing tables, determines the Diameter server that
> stores the information allocated to such user.  Then it builds a
> Diameter LIA message (step 3) that includes a Result-Code AVP set to
> DIAMETER_REDIRECT_INDICATION and one or more Redirect-Host AVPs,
> whose values are set to one or more URIs of Diameter servers that
> store the information related to such user.  Then the Diameter
> client in SIP server 1 builds a new LIR message (step 4) addressed
> to any of the Diameter servers received in the Redirect-Host AVPs." to
> "The Diameter SL, based on the contents of the SIP-AOR AVP
> and its own routing tables, determines the Diameter server that
> stores the information allocated to such user.  Then it builds a
> Diameter LIA message (step 3) that includes a Result-Code AVP set to
> DIAMETER_REDIRECT_INDICATION and exactly one Redirect-Host AVP,
> the value of which is set to the URI of the Diameter server that
> stores the information related to such user.  Then the Diameter
> client in SIP server 1 builds a new LIR message (step 4) addressed
> to the Diameter server received in the Redirect-Host AVP." in Section 5.10.
> 

Ok, as I said, it works. If we do this change, we also need to remove 
the star '*' in from of [Redirect-Host] in each command that allows such 
AVP.

/Miguel

> 
>>/Miguel
> 
> 
> Hope this helps,
> 
> ~gwz
> 
> Why is it that most of the world's problems can't be solved by simply
>   listening to John Coltrane? -- Henry Gabriel

-- 
Miguel A. Garcia           tel:+358-50-4804586
sip:[email protected]
Nokia Research Center      Helsinki, Finland