Re: [Dime] [dime] #70 (draft-ietf-dime-ovli): Appendix B - Example

["Wiehe, Ulrich (NSN - DE/Munich)" <[e-mail]>]

Jacques,

in this scenario where the client supports DOIC my understanding is:
If there is a realm overload, the agent will receive only those realm routed requests that survived a throttling at the client. There is no point for the agent to throttle again.

Anyway this seems not to be related to #70.

See also inline.

Ulrich

-----Original Message-----
From: ext TROTTIN, JEAN-JACQUES (JEAN-JACQUES) [mailto:[e-mail]] 
Sent: Tuesday, September 09, 2014 12:48 PM
To: [e-mail]; Wiehe, Ulrich (NSN - DE/Munich); [e-mail]; [e-mail]
Subject: RE: [Dime] [dime] #70 (draft-ietf-dime-ovli): Appendix B - Example

Dear all

Another remark on this type of use cases.

There is a realm overload, the DA receives a realm routed request and decide to throttle it and generates a Diameter error (congestion or too busy under discussion). The request was not sent to any server; which Origin-Host AVP does the DA puts in the unsuccessful answer to the client. RFC6733 6.3 states that "Origin-Host AVP MUST be present in all Diameter messages. This AVP identifies the endpoint that originated the Diameter message". 

Another clarification, in our discussions, we speak of OLRs put in successful answers;  my understanding is that OLRs may also be present in unsuccessful answers (with a Diameter error). Do we agree on this?
[Wiehe, Ulrich (NSN - DE/Munich)] I agree.

Best regards

Jacques    

-----Message d'origine-----
De : DiME [mailto:[e-mail]] De la part de TROTTIN, JEAN-JACQUES (JEAN-JACQUES)
Envoyé : mardi 9 septembre 2014 12:01
À : [e-mail]; Wiehe, Ulrich (NSN - DE/Munich); [e-mail]; [e-mail]
Objet : Re: [Dime] [dime] #70 (draft-ietf-dime-ovli): Appendix B - Example

Hi MCruz, Ulrich

I think we already had some discussion on the OLRs to be reported by DA to clients in this type of use cases.

a) In step 4), in the existing draft wording, the DA sends a successful answer to the client with origin host = S1 and an Host type OLR related to S1. As the client will have further Host routed requests to this S1 host, it seemed good for the client to be immediately informed of the S1 host overload, so to apply throttling to further S1 host requests. This has no impact on Realm routed requests.

In Step 8), the DA has determined a realm overload and send a realm type OLR in the answer and also, as in step 4) the Host type OLR related to the Origin Host S2. This works. The point that was discussed in our previous discussions, is that the answer will contains two OLRs  a realm type one and a host type one, which was accepted at this time. Is it this point you consider as an issue, and why? 

b) this drives to some other remarks. The IETF draft indicates that, in 5.3, when a reporting node requests traffic reduction, it sends OLRs in all answer messages (with the additional MCRuz proposal that if not present this means no change), so this drives to have a realm type  OLR  related to the Origin-Realm AVP (when overloaded) of an answer and a Host type OLR related to the Origin-Host  AVP (when overloaded) of the same answer. The example in a) is one such case. Do you want to modify 5.3 to introduce additional rules, which ones?

Best regards

JJacques 

-----Message d'origine-----
De : DiME [mailto:[e-mail]] De la part de Wiehe, Ulrich (NSN - DE/Munich) Envoyé : lundi 8 septembre 2014 16:21 À : [e-mail]; [e-mail]; [e-mail] Objet : Re: [Dime] [dime] #70 (draft-ietf-dime-ovli): Appendix B - Example

Maria Cruz,

I share your concern.

Please find some comments attached.

Best regards
Ulrich

-----Original Message-----
From: DiME [mailto:[e-mail]] On Behalf Of ext dime issue tracker
Sent: Friday, September 05, 2014 9:50 AM
To: [e-mail]; [e-mail]
Cc: [e-mail]
Subject: [Dime] [dime] #70 (draft-ietf-dime-ovli): Appendix B - Example

#70: Appendix B - Example

 In the example included in Appendix B, it is considered that the Agent  reports Host overload directly back to the Client, when the Client request  was for the Realm, withouth Destination Host (or direct connection).
 I do not agree about this behaviour.
 Agent will provide Host overload to the Client only when the request was  sent to one specific host.

 Example shall be modified.

 Proposed modification:


         Client     Agent      S1        S2        S3
            |         |         |         |         |
            |(1) Request (DR:realm)       |         |
            |-------->|         |         |         |
            |         |         |         |         |
            |         |         |         |         |
            |         |Agent selects S1   |         |
            |         |         |         |         |
            |         |         |         |         |
            |         |         |         |         |
            |         |(2) Request (DR:realm)       |
            |         |-------->|         |         |
            |         |         |         |         |
            |         |         |         |         |
            |         |         |S1 overloaded, returns OLR
            |         |         |         |         |
            |         |         |         |         |
            |         |         |         |         |
            |         |(3) Answer (OH:S1,OLR:RT=DH)
            |         |<--------|         |         |
            |         |         |         |         |
            |         |         |         |         |
            |         |sees OLR,routes next DR traffic to S2&S3
            |         |         |         |         |
            |(5) Request (DR:realm)       |         |
            |-------->|         |         |         |
            |         |         |         |         |
            |         |         |         |         |
            |         |Agent selects S2   |         |
            |         |         |         |         |
            |         |         |         |         |
            |         |         |         |         |
            |         |(6) Request (DR:realm)       |
            |         |------------------>|         |
            |         |         |         |         |
            |         |         |         |         |
            |         |         |         |S2 is overloaded...
            |         |         |         |         |
            |         |         |         |         |
            |         |         |         |         |
            |         |(7) Answer (OH:S2, OLR:RT=DH)|
            |         |<------------------|         |
            |         |         |         |         |
            |         |         |         |         |
            |         |Agent sees OLR, realm now overloaded
            |         |         |         |         |
            |         |         |         |         |
            |         |         |         |         |
            |(8) Answer (OLR: RT=R)
            |<--------|         |         |         |
            |         |         |         |         |
            |         |         |         |         |
            |Client throttles DR:realm
            |         |         |         |         |
            |         |         |         |         |
            |         |         |         |         |
            |         |         |         |         |
            |         |         |         |         |



       Figure 8: Mix of Destination-Host and Destination-Realm Routed
                                  Requests

    1.  The client sends a request with no Destination-Host AVP (that is,
        a Destination-Realm routed request.)

    2.  The agent follows local policy to select a server from its peer
        table.  In this case, the agent selects S2 and forwards the
        request.

    3.  S1 is overloaded.  It sends an answer indicating success, but also
        includes an overload report.  Since the overload report only
        applies to S1, the ReportType is "Destination-Host".

    4.  The agent sees the overload report, and records that S1 is
        overloaded by the value in the Reduction-Percentage AVP.  It
        begins diverting the indicated percentage of realm-routed traffic
        from S1 to S2 and S3.

    5.  The client sends another Destination-Realm routed request.

    6.  The agent selects S2, and forwards the request.

    7.  It turns out that S2 is also overloaded, perhaps due to all that
        traffic it took over for S1.  S2 returns an successful answer
        containing an overload report.  Since this report only applies to
        S2, the ReportType is "Destination-Host".

    8.  The agent sees that S2 is also overloaded by the value in
        Reduction-Percentage.  This value is probably different than the
        value from S1's report.  The agent diverts the remaining traffic
        to S3 as best as it can, but it calculates that the remaining
        capacity across all three servers is no longer sufficient to
        handle all of the realm-routed traffic.  This means the realm
        itself is overloaded.  The realm's overload percentage is most
        likely different than that for either S1 or S2.
        The agent generates a new report for the realm of
        "realm", and inserts that report into the answer.  The client
        throttles requests with no
        Destination-Host AVP at requested rate.

-- 
-------------------------------------+----------------------------------
-------------------------------------+---
 Reporter:                           |      Owner:  draft-ietf-dime-
  [e-mail]  |  [e-mail]
     Type:  defect                   |     Status:  new
 Priority:  minor                    |  Milestone:
Component:  draft-ietf-dime-ovli     |    Version:
 Severity:  Active WG Document       |   Keywords:
-------------------------------------+----------------------------------
-------------------------------------+---

Ticket URL: <http://trac.tools.ietf.org/wg/dime/trac/ticket/70>
dime <http://tools.ietf.org/wg/dime/>

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