Re: [Dime] AD review of draft-ietf-dime-drmp-03

[<[e-mail]>]

i will let Steve react but I can give my feeling :)

The priority is set by the Diameter or Diameter server, not by agent.

It is somehow describe in section 6 Theory of Operation

   2.  Agents handing the request - Agents use the priority information
       when making routing decisions.  This can include determining
       which requests to route first, which requests to throttle and
       where the request is routed.  For instance, requests with higher
       priority might have a lower probability of being throttled.  The
       mechanism for how the agent determines which requests are
       throttled is implementation dependent and is outside the scope of
       this document.  The agent also saves the transaction priority in
       the transaction state, either as locally managed state or using
       the Proxy-Info mechanism defined in [RFC6733].  This will be used
       when handling the associated answer message for the transaction.

Agents are just using this information if present. They are not modify it or include it if absent.
It is said in section 8.  Normative Behavior

      Note: This guidance on the handling of messages without a priority
      does not result in a Diameter agent inserting a DRMP AVP into the
      message.  Rather, it gives guidance on how that specific
      transaction should be treated when its priority is compared with
      other requests.  When a Diameter agent relays the request it will
      not insert a DRMP AVP with a priority value of 10.

It could be possible to clarify it as follow:

in section 6, the end of the point 2 could be enhanced as follow:

   2.  Agents *handling* the request - Agents use the priority information
       when making routing decisions.  This can include determining
       which requests to route first, which requests to throttle and
       where the request is routed.  For instance, requests with higher
       priority might have a lower probability of being throttled.  The
       mechanism for how the agent determines which requests are
       throttled is implementation dependent and is outside the scope of
       this document.  The agent also saves the transaction priority in
       the transaction state, either as locally managed state or using
       the Proxy-Info mechanism defined in [RFC6733].  This will be used
       when handling the associated answer message for the transaction.
       *Agents are not supposed to modify or include priority information in
       in forwarded requests or answers.*

The "not supposed" is used because it is difficult to use normative wording here.

In section 8, a new requirement could be added, right after " Diameter agents MAY use routing priority information..."

   Diameter agents SHOULD NOT modify or include the DRMP AVP when 
   relaying request and answer messages.

Just a proposal, waiting for Steve and WG comments.

Regards,

Lionel


> -----Message d'origine-----
> De : DiME [mailto:[e-mail]] De la part de Stephen Farrell
> Envoyé : vendredi 4 mars 2016 18:07
> À : [e-mail]
> Objet : [Dime] AD review of draft-ietf-dime-drmp-03
> 
> 
> Hiya,
> 
> I just have one question I'd like to ask the wg about before I start IETF LC.
> 
> You don't say if priorities are intended to be modified after they have been
> set. In the security considerations you do say that this could be done
> maliciously, and you do say that priorities need to be dropped if received
> from a source not trusted for that, but you never say if it's considered ok or
> not for e.g. an agent to change a priority for some local policy reason. Don't
> you need to say that somewhere? (And apologies if you do say it somewhere
> and I missed it:-)
> 
> There are some nits below, you can handled these before or after IETF LC,
> whichever is best.
> 
> Cheers,
> S.
> 
> 
> - Section 5: URL and MME aren't expanded. Since you're just using it as an
> example, I'd say expanding this will help any reader who's not a 3gpp
> afficionado.
> 
> - Section 8, "The priority marking scheme SHOULD NOT require the Diameter
> Agents to understand application specific AVPs."
> Isn't that a bogus use of 2119 language since we're not expressing
> requirements here? s/SHOULD NOT/does not/ would seem better.
> 
> - Section 8, People will ask "why default to 10?" I recall the WG discussed this
> but iirc mostly didn't care too much but it might be nice to justify 10 if there's
> a way to do it that doesn't amount to "just because" :-)
> 
> - Section 8, The "When setting and using..." paragraphs are quite verbose.
> It'd be no harm to make that shorter, e.g. by just saying: "For all integers x,y
> in [0,15] treat PRIORITY_<x> as lower priority than PRIOIRTY_<y> when y<x"
> You could do something similar in 9.1.
> 
> I-D nits:
> 
>   == Unused Reference: 'RFC5226'
>   == Unused Reference: 'RFC4412'


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