Re: [Dime] OVLI: comments to 4.6

[Jouni <[e-mail]>]

On Dec 6, 2013, at 2:10 PM, Wiehe, Ulrich (NSN - DE/Munich) wrote:

> Dear all,
>  
> here are comments to clause 4.6:
>  
> It has already been proposed to change the type of the OC-Report-Type AVP from Enumerated to Unsinged64 in order to avoid potential extensibility problems.  

I do not see how changing the type to unsigned would help with the extensibility on
an assumption we create an IANA maintained registry for it. Unsigned64 will have
exactly the same issues as enumerated unless we define report type semantics to
something like what we have on OC-Feature AVP. How the receiver of the report type
reacts when it sees a flag bit that is does not understand? If the content and
handling  of the OC-OLR somehow depends on the unknown flag bit, the receiver has
no other choice than drop the OLR, since it cannot be sure how to handle the report
as a whole.

The only ways around I see here are:
a) you can extend report types when defining new applications
b) or when both ends have a mutually supported & advertised feature that maps
   to a report type (that has been defined after the publication of this 
   spec)

Other than those, IMHO, are just repackaging the issue into different form.


- Jouni

> In addition to that, I think that the purpose of the Report-Type is to let the reacting node know to which (future) request commands the overload treatment should apply:
> 
> For a host report-type the overload treatment should apply to all request commands for which
> a) The request command's Application-ID matches the Application-Id of the OC-Report-Type AVP's encapsulating answer command and
> b) The request command's Destination-Host is present and 
> c) The request command's Destination-Host matches the Origin-Host of the OC-Report-Type AVP's encapsulating answer command
> 
> For a realm report-type the overload treatment should apply to all request commands for which
> a) <see a) above> and
> d) The request command's Destination-Host is absent and 
> e) The request command's Destination Realm matches the Origin-Realm of the OC-Report-Type AVP's encapsulating answer command.
> 
> The proposal now is to assign individual bits of the Unsinged64 type to a), b), c), d), and e):
> 
> Proposed text:
>   4.6 OC-Report-Type AVP
> 
>   The OC-Report-Type AVP (AVP code TBD5) is type of Unsigned64 and contains a 64 bit flags field of a request
>   command's characteristics.
> 
>   The following characteristics are defined in this document:
> 
>   APPLICATION_ID_MATCH (0x0000000000000001)
> 
>   When this flag is set by the overload reporting endpoint it means that the overload treatment should apply only
>   to those request commands with an Application-ID that matches the Application-Id of the OC-Report-Type AVP's
>   encapsulating answer command.
> 
>   DESTINATION_HOST_PRESENT (0x0000000000000002)
> 
>   When this flag is set by the overload reporting endpoint it means that the overload treatment should apply only
>   to those request commands containing a Destination-Host AVP.
> 
>   DESTINATION_HOST_MATCH (0x0000000000000004)
> 
>   When this flag is set by the overload reporting endpoint it means that the overload treatment should apply only
>   To those request commands with an Destination-Host AVP that matches the Origin-Host of the OC-Report-Type AVP's
>   encapsulating answer command.
> 
>   DESTINATION_HOST_ABSENT (0x0000000000000008)
> 
>   When this flag is set by the overload reporting endpoint it means that the overload treatment should apply only
>   to those request commands not containing a Destination-Host AVP.
> 
>   DESTINATION_REALM_MATCH (0x0000000000000010)
> 
>   When this flag is set by the overload reporting endpoint it means that the overload treatment should apply only
>   to those request commands with an Destination-Host AVP that matches the Origin-Host of the OC-Report-Type AVP's
>   encapsulating answer command.
> 
>   Combinations other than 
>   1) APPLICATION_ID_MATCH and DESTINATION_HOST_PRESENT and DESTINATION_HOST_MATCH
>   and
>   2) APPLICATION_ID_MATCH and DESTINATION_HOST_ABSENT and DESTINATION_REALM_MATCH
>   require a mutually agreed extension.
> 
> 
> 
> 
> One extension required by 3GPP applications is the Overload Mitigation Differentiation per client (see 3GPP TR 29.809 clause 6.4.7. To address this, a new value would be needed e.g.
> 
>   ORIGIN_HOST_MATCH (0x0000000000000020)
> 
>   When this flag is set by the overload reporting endpoint it means that the overload treatment should apply only
>   to those request commands with an Origin-Host AVP that matches the Destination-Host of the OC-Report-Type AVP's
>   encapsulating answer command.
> 
> With this extension the following additional combinations would be allowed:
> 3) APPLICATION_ID_MATCH and DESTINATION_HOST_PRESENT and DESTINATION_HOST_MATCH and ORIGIN_HOST_MATCH
> and
> 4) APPLICATION_ID_MATCH and DESTINATION_HOST_ABSENT and DESTINATION_REALM_MATCH and ORIGIN_HOST_MATCH
> 
> Another potential extension is Diameter Agent Overload. To address this, a new value would be needed e.g.
> 
>   NEXT_HOP_MATCH (0x0000000000000040)
> 
>   When this flag is set by the overload reporting endpoint it means that the overload treatment should apply only
>   to those request commands sent to the same next hop the OC-Report-Type AVP's encapsulating answer command was received from.
> 
> 
> Best regards
> Ulrich
> 
> 
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