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Diameter Maintenance and Extensions                             L. Bertz
Internet-Draft                                                    Sprint
Intended status: Standards Track                       February 27, 2017
Expires: August 31, 2017

                        Diameter Predicted Units


   This document specifies the conveyance of predicted usage information
   for proper dimensioning of network services that use Diameter based

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on August 31, 2017.

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   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
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   than English.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Predicted Service AVPs  . . . . . . . . . . . . . . . . . . .   3
     3.1.  Predicted-Service-Units . . . . . . . . . . . . . . . . .   3
     3.2.  Service-Cost-Information  . . . . . . . . . . . . . . . .   4
   4.  Usage Examples  . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   When a User is authorized to use a service via Diameter applications
   such as [RFC4006] or [RFC7155], the Client is not aware of the
   average load placed upon it by User.  This can lead to overload
   situations or the Diameter Client redirecting or denying services to
   valid Users even though their presence may overload the service.

   Given virtualization and the use of many software based services the
   service capacity varies on a service instance, i.e. Diameter Client,

   This specification introduces the Predicted-Service-Units Attribute
   Value Pair (AVP).  This information conveys the predicted usage
   introduced on the service by the authorized User.  Such information
   can be used by the Diameter Client to estimate future load and
   proactively manage its resources.

   Although this informaiton is conveyed from the Diameter Server to the
   Client several system aspects are out of the scope of this document:

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   o  How the Diameter Server acquired the information contained in the
      Predicted-Service-Units AVP.

   o  How the values in the Predicted-Service-Units AVP were determined.

   o  The accuracy or validity of the values in the Predicted-Service-
      Units AVP.

   o  Specific actions the Diameter Client should take when its service
      functions are overloaded.

   o  Specific actions the Diameter Client takes to bring itself in/out
      of service for new or existing Users.

   When the value(s) or multiple types of Costs are provided they are
   represented by the Time-Of-Day-Condition AVP defined in [RFC5777] and
   contained in a Predicted-Service-Units-Series AVP.  This AVP contains
   one or more Predicted-Service-Units.  Multiple Cost types, e.g.  CC-
   Total-Octets and CC-Time, may be represented in the same Predicted-
   Service-Units entry and in the same Predicted-Service-Units-Series so
   long as no overlapping times exist for the same Cost Type.

2.  Terminology

   In this document, the key words "MAY", "MUST", "MUST NOT",
   interpreted as described in [RFC2119].

3.  Predicted Service AVPs

3.1.  Predicted-Service-Units

   The Predicted-Service-Units AVP (AVP Code TBD1) is of type Grouped
   and contains the amount of units that the Diameter credit-control
   client can expect to provide to the end user until the service must
   be released or the new Credit-Control-Request must be sent, if a
   Granted-Service-Unit AVP [RFC4006] has been applied to the user's
   service.  A client is not required to implement all of the unit
   types, and it MUST ignore unknown or unsupported unit types.

   The Predicted-Service-Units AVP is defined as follows (per the
   grouped- avp-def of [RFC6733]):

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            Predicted-Service-Units ::= < AVP Header: TBD1 >
                                       [ CC-Time ]
                                       [ CC-Money ]
                                       [ CC-Total-Octets ]
                                       [ CC-Input-Octets ]
                                       [ CC-Output-Octets ]
                                       [ CC-Service-Specific-Units ]
                                       [ Time-Of-Day-Condition ]
                                      *[ AVP ]

   The Time-Of-Day-Condition AVP is defined in [RFC5777], all other AVPs
   are defined in [RFC4006].

   The presence of this information is provided as anticipated load
   information to the Diameter Client and is not intended to be
   prescriptive in any manner regarding the user's service.

   When the Time-Of-Day-Condition AVP is not present, the value(s) are
   assumed to apply for the duration of the authorized session until
   this value is updated as part of the Diameter application, e.g. a
   Diameter Re-Auth-Request/Answer (RAR/RAA) message [RFC6733].

3.2.  Service-Cost-Information

   The Predicted-Service-Units AVP (AVP Code TBD2) is of type Grouped,
   and contains one or more Predicted-Service-Units with non-overlapping
   times for each specific Cost type..

   A client is not required to implement all of the unit types, and it
   MUST ingore unknown or unsupported unit types.

   It is defined as follows (per the grouped-avp-def of [RFC6733]):

             Predicted-Service-Units-Series ::= < AVP Header: TBD2 >
                                       1*{ Predicted-Service-Units }

   For each specific type of Cost, e.g.  CC-Time, any two Predicted-
   Service-Units values in the series MUST NOT contain overlapping time
   windows specified in their Time-Of-Day-Condition values.  When an
   entry has no Time-Of-Day-Condition present it is assumed to apply at
   all times.

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4.  Usage Examples

   When Predicted-Service-Units are returned as part of an authorization
   per [RFC7155] or [RFC4006], the client MAY use this information as
   guidance on projected load the new user will generate on the service.

   If the client supports/understnds the information provided in the
   Predicted-Service-Units AVP, it can update its projected load.  Based
   upon this information it MAY take one or more of the following
   actions (this is not exhaustive):

   o  Redirect at the service / protocol level any new service requests.

   o  Begin enforcing mechanisms to reduce the amount of service load on
      a subset of services already established.

   o  Remove itself from any system that directs new service requests to

   o  Initiate administrative functions to increase its capacity or
      start the process of creating new intances to service requests.

5.  IANA Considerations

   IANA allocated AVP codes in the IANA-controlled namespace registry
   specified in Section 11.1.1 of [RFC6733] for the following AVPs that
   are defined in this document.

   | AVP                            | AVP   | Section       | Data     |
   |                                | Code  | Defined       | Type     |
   | Predicted-Service-Units        | TBD1  | Section 3.1   | GROUPED  |
   | Predicted-Service-Units-Series | TBD2  | Section 3.2   | GROUPED  |

6.  Security Considerations

   The Diameter base protocol [RFC6733] requires that each Diameter
   implementation use underlying security; i.e., TLS/TCP, DTLS/SCTP or
   IPsec.  These mechanisms are believed to provide sufficient
   protection under the normal Internet threat model; that is, assuming
   that the authorized nodes engaging in the protocol have not been
   compromised, but that the attacker has complete control over the
   communication channels between them.  This includes eavesdropping,
   message modification, insertion, and man-in-the-middle and replay
   attacks.  Note also that this application includes a mechanism for
   application layer replay protection by means of the Session-Id from

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   [RFC6733] and CC- Request-Number, which is specified in this
   document.  The Diameter credit-control application is often used
   within one domain, and there may be a single hop between the peers.
   In these environments, the use of TLS/TCP, DTLS/SCTP or IPsec is
   sufficient.  The details of TLS/TCP, DTLS/SCTP or IPsec related
   security considerations are discussed in the [RFC6733].

   Because this application conveys past usage information (directly or
   indirectly), it increases the interest for various security attacks.
   Therefore, all parties communicating with each other MUST be
   authenticated, including, for instance, TLS client-side
   authentication.  In addition, authorization of the client SHOULD be
   emphasized; i.e., that the client is allowed to perform credit-
   control for a certain user.  The specific means of authorization are
   outside of the scope of this specification but can be, for instance,
   manual configuration.

   The attributes provided by this solution MUST be assumed to be
   privacy sensitive by both the client and server.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC4006]  Hakala, H., Mattila, L., Koskinen, J-P., Stura, M., and J.
              Loughney, "Diameter Credit-Control Application", RFC 4006,
              DOI 10.17487/RFC4006, August 2005,

   [RFC5777]  Korhonen, J., Tschofenig, H., Arumaithurai, M., Jones, M.,
              Ed., and A. Lior, "Traffic Classification and Quality of
              Service (QoS) Attributes for Diameter", RFC 5777,
              DOI 10.17487/RFC5777, February 2010,

   [RFC6733]  Fajardo, V., Ed., Arkko, J., Loughney, J., and G. Zorn,
              Ed., "Diameter Base Protocol", RFC 6733,
              DOI 10.17487/RFC6733, October 2012,

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7.2.  Informative References

   [RFC7155]  Zorn, G., Ed., "Diameter Network Access Server
              Application", RFC 7155, DOI 10.17487/RFC7155, April 2014,

Author's Address

   Lyle Bertz
   6220 Sprint Parkway
   Overland Park, KS  66251
   United States

   Email: lylebe551144@gmail.com

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