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Authentication, Authorization and                              F. Alfano
Accounting                                                     P. McCann
Internet-Draft                                       Lucent Technologies
Expires: January 19, 2006                                  H. Tschofenig
                                                               T. Tsenov
                                                                 Siemens
                                                           July 18, 2005


                Diameter Quality of Service Application
                    draft-alfano-aaa-qosprot-03.txt

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
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   This Internet-Draft will expire on January 19, 2006.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This document describes a Diameter Application that performs
   Authentication, Authorization, and Accounting for Quality of Service
   (QoS) reservations.  This protocol is used by elements along the path
   of a given application flow to authenticate a reservation request,
   ensure that the reservation is authorized, and to account for



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   resources consumed during the lifetime of the application flow.
   Clients that implement the Diameter QoS application contact an
   authorizing entity/application server that is located somewhere in
   the network, allowing for a wide variety of flexible deployment
   models.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Framework  . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     3.1   Network element functional model . . . . . . . . . . . . .  7
     3.2   Authorization models . . . . . . . . . . . . . . . . . . .  9
     3.3   QoS authorization considerations . . . . . . . . . . . . . 10
   4.  Diameter QoS Authorization session establishment and
       management . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     4.1   Session parties' functional description  . . . . . . . . . 14
       4.1.1   End-user initiator of the QoS signaling session  . . . 14
       4.1.2   QoS policy aware transport plane element
               functionality  . . . . . . . . . . . . . . . . . . . . 15
       4.1.3   Authorizing Entity functionality . . . . . . . . . . . 16
     4.2   QoS authorization session re-authorization . . . . . . . . 16
       4.2.1   Client-side initiated Re-Authorization . . . . . . . . 16
       4.2.2   Server-side initiated Re-Authorization . . . . . . . . 16
     4.3   Server-side initiated QoS parameter provisioning . . . . . 17
     4.4   Session Termination  . . . . . . . . . . . . . . . . . . . 17
       4.4.1   Client-side initiated session termination  . . . . . . 17
       4.4.2   Server-side initiated session termination  . . . . . . 17
   5.  Accounting . . . . . . . . . . . . . . . . . . . . . . . . . . 18
   6.  Diameter QoS authorization application Messages  . . . . . . . 19
     6.1   QoS-Authorization Request (QAR)  . . . . . . . . . . . . . 20
     6.2   QoS-Authorization Answer . . . . . . . . . . . . . . . . . 20
     6.3   QoS-Install Request  . . . . . . . . . . . . . . . . . . . 21
     6.4   QoS-Install Request  . . . . . . . . . . . . . . . . . . . 22
   7.  Diameter QoS Authorization Application AVPs  . . . . . . . . . 23
     7.1   Diameter Base Protocol AVPs  . . . . . . . . . . . . . . . 23
     7.2   Credit Control application AVPs  . . . . . . . . . . . . . 23
     7.3   Authentication/Authorization AVPs  . . . . . . . . . . . . 24
     7.4   Accounting AVPs  . . . . . . . . . . . . . . . . . . . . . 24
     7.5   Diameter QoS Application Defined AVPs  . . . . . . . . . . 24
   8.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 33
   10.   Contributors . . . . . . . . . . . . . . . . . . . . . . . . 34
   11.   Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 35
   12.   Open Issues  . . . . . . . . . . . . . . . . . . . . . . . . 36
   13.   References . . . . . . . . . . . . . . . . . . . . . . . . . 37
     13.1  Normative References . . . . . . . . . . . . . . . . . . . 37
     13.2  Informative References . . . . . . . . . . . . . . . . . . 37



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       Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 39
       Intellectual Property and Copyright Statements . . . . . . . . 40

















































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1.  Introduction

   To meet the Quality of Service needs of applications such as Voice-
   over-IP in a heavily loaded network, packets belonging to real-time
   application flows must be identified and segregated from other
   traffic to ensure that bandwidth, delay, and loss rate requirements
   are met.  In addition, new flows should not be added to the network
   when it is at or near capacity, which would result in degradation of
   quality for all flows carried by the network.

   In some cases, these goals can be achieved with mechanisms such as
   differentiated services and/or end-to-end congestion and admission
   control.  However, when bandwidth is scarce and must be carefully
   managed, such as in cellular networks, or when applications and
   transport protocols lack the capability to perform end-to-end
   congestion control, explicit reservation techniques are required.  In
   these cases, the endpoints will send reservation requests to edge
   and/or interior nodes along the communication path.  In addition to
   verifying whether resources are available, the recipient of a
   reservation request must also authenticate and authorize the request,
   especially in an environment where the endpoints are not trusted.  In
   addition, these nodes will generate accounting information about the
   resources used and attribute usage to the requesting endpoints.  This
   will enable the owner of the network element to generate usage-
   sensitive billing records and to understand how to allocate new
   network capacity.

   A variety of protocols could be used to make a QoS request, including
   RSVP [RFC2210], NSIS [I-D.ietf-nsis-qos-nslp], link-specific
   signaling or even SIP/SDP [RFC2327].  This document focuses on
   supporting the NSIS QoS NSLP.  This will have an implication on the
   content and format of the flow identifiers and QoS attributes that
   represent a particular reservation request within the Diameter QoS
   application; however, other aspects of its operation can easily be
   generalized to other QoS signaling protocols.  The Diameter QoS
   application could be used directly in the context of these other
   reservation protocols, given the definition of a suitable conversion
   between the representations used by those protocols and the ones used
   by NSIS.












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2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

   The following terms are used in this document:

   Application Server

      An application server is a network entity that exchanges signaling
      messages with an application endpoint.  It may be a source of
      authorization for QoS-enhanced application flows.  For example, a
      SIP server is one kind of application server.

   Application Endpoint

      An application endpoint is an entity in an end user device that
      exchanges signaling messages with application servers or directly
      with other application endpoints.  Based on the result of this
      signaling, the endpoint will make a request for QoS from the
      network.  For example, a SIP User Agent is one kind of application
      endpoint.

   Authorizing Entity

      The authorizing entity is that entity responsible for authorizing
      QoS requests for a particular application flow.  This may be a AAA
      server (with a subscriber database) or an application server or
      some other entity.

   AAA Cloud

      A network of AAA proxy/broker arrangements.


   Furthermore, we use terminology defined in [RFC3588].














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3.  Framework

   The Diameter QoS application runs between a network element receiving
   QoS reservation requests (acting as a AAA client) and the resource
   authorizing entity (acting as a AAA server).  A high-level picture of
   the resulting architecture is shown in Figure 1.


                                 +-------------+
                                 | Resource    |
                                 | Authorizing |
                                 | Entity      |
                                 +-----+-------+
                                       |
                                       |
                                /\-----+-----/\
                            ////               \\\\
                          ||                       ||
                         |         AAA Cloud         |
                          ||                       ||
                            \\\\               ////
                                \-------+-----/
                                        |
                         +---+--+   +---+--+   +---+--+
            Application  |      |   |      |   |      |
          ===============+  NE  +===+  NE  +===+  NE  +========>>
               Flow      |      |   |      |   |      |
                         +------+   +------+   +------+

               Figure 1: An Architecture supporting QoS-AAA

   Figure 1 depicts network elements through which application flows
   need to pass, a cloud of AAA servers, and an authorizing entity.
   Note that there may be more than one router that needs to interact
   with the AAA cloud along the path of a given application flow,
   although the figure only depicts one for clarity.  Routers will
   request authorization for QoS from the AAA cloud, which will route
   the request, for example, to the home network where the home
   authorizing entity will return authorizing information.

   In more complex deployment models, the authorization will be based on
   dynamic application state, so the request must be authenticated and
   authorized based on information from one or more application servers.
   If defined properly, the interface between the routers and AAA cloud
   would be identical in both cases.  Routers are therefore insulated
   from the details of particular applications and need not know that
   application servers are involved at all.  Also, the AAA cloud would
   naturally encompass business relationships such as those between



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   network operators and third-party application providers, enabling
   flexible intra- or inter-domain authorization, accounting, and
   settlement.

3.1  Network element functional model

   Figure 2 depicts a logical operational model of resource management
   in a router.











































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          +-----------------------------------------------------+
          | DIAMETER Client                                     |
          | Functionality                                       |
          | +---------------++---------------++---------------+ |
          | | User          || Authorization || Accounting    | |
          | | Authentication|| of QoS        || for QoS       | |
          | +---------------+| Requests      || Traffic       | |
          |                  +---------------++---------------+ |
          +-----------------------------------------------------+
                 ^                            ^
                 v                            v
            +--------------+            +----------+
            |QoS Signaling |            | Resource |
            |Msg Processing|<<<<<>>>>>>>|Management|
            +--------------+            +----------+
                 .  ^   |              *      ^
                 |  v   .            *        ^
            +-------------+        *          ^
            |Signaling msg|       *           ^
            | Processing  |       *           V
            +-------------+       *           V
                 |      |         *           V
     ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
                 .      .         *           V
                 |      |         *     .............................
                 .      .         *     .   Traffic Control         .
                 |      |         *     .                +---------+.
                 .      .         *     .                |Admission|.
                 |      |         *     .                | Control |.
       +----------+    +------------+   .                +---------+.
   <-.-|  Input   |    | Outgoing   |-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.->
       |  Packet  |    | Interface  |   .+----------+    +---------+.
   ===>|Processing|====| Selection  |===.|  Packet  |====| Packet  |.=>
       |          |    |(Forwarding)|   .|Classifier|     Scheduler|.
       +----------+    +------------+   .+----------+    +---------+.
                                        .............................
           <.-.-> = signaling flow
           =====> = data flow (sender --> receiver)
           <<<>>> = control and configuration operations
           ****** = routing table manipulation

                Figure 2: Network element functional model

   Processing of incoming QoS reservation requests includes three
   actions: admission control, authorization and resource reservation.

   The admission control function provides information for available
   resources and determines whether there are enough resources to



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   fulfill the request.  Authorization is performed by the Diameter
   client function which involves contacting an authorization entity
   through the AAA cloud shown in Section 3.  If both checks are
   successful, the authorized QoS parameters are set in the packet
   classifier and the packet scheduler.  Note that the parameters passed
   to the Traffic Control function may be different from requested QoS
   (depending on the authorization decision).  Once the requested
   resource is granted, the Resource Management function provides
   accounting information to the Authorizing entity using the Diameter
   client function.

3.2  Authorization models

   With respect to NSIS signaling, different authorization models have
   been investigated and discussed in detail in [I-D.tschofenig-nsis-
   aaa-issues] and in [I-D.tschofenig-nsis-qos-authz-issues].  From the
   Diameter QoS application's point of view these models differ in type
   of information that need to be carried.  Here we focus on the 'Three
   party approach' model (Figure 3) and the 'Token based three party
   approach' model (Figure 4).


                                        +--------------+
                                        | Entity       |
                                        | authorizing  | <......+
                                        | resource     |        .
                                        | request      |        .
                                        +------------+-+        .
                                        --^----------|--   .    .
                                   /////  |          |  \\\\\   .
                                 //       |          |       \\ .
                                |     QoS | QoS AAA  | QoS     |.
                                |    authz| protocol |authz    |.
                                |     req.|          | res.    |.
                                 \\       |          |       // .
                                   \\\\\  |          |  /////   .
                          QoS           --|----------v--   .    .
       +-------------+    request       +-+------------+        .
       |  Entity     |----------------->| BE           |        .
       |  requesting |                  | performing   |        .
       |  resource   |granted / rejected| QoS          |  <.....+
       |             |<-----------------| reservation  | financial
       +-------------+                  +--------------+ settlement

                      Figure 3: Three Party Approach

   In the 'Three party approach' model, a resource request by the end
   host is received at the router in the local network and then sent to



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   the user's home network (after processing) where authorization is
   provided.  The response is then returned and resources are granted
   (in case of a successful authorization decision).  The interaction
   between the visited network and the home network establishes the
   necessary financial infrastructure to later charge the user for the
   consumed resources.


                               financial settlement
                                ...........................+
      Authorization             V             -------      .
      Token Request   +--------------+      / QoS AAA \    .
      +-------------->| Entity       |     /  protocol \   .
      |               | authorizing  +--------------+   \  .
      |               | resource     |   |          |    | .
      |        +------+ request      |<--+----+     |    | .
      |        |      +--------------+  |QoS  |     |QoS  |.
      |        |                        |authz|     |authz|.
      |        |Authorization           |req.+|     |res. |.
      |        |Token                   |Token|     |     |.
      |        |                         |    |     | .  | .
      |        |                          \   |     | . /  .
      |        |                            \ |     | /    .
      |        |      QoS request             |-----V .    .
    +-------------+ + Authz. Token   +--------+-----+      .
    |  Entity     |----------------->| BE           |      .
    |  requesting |                  | performing   |      .
    |  resource   |granted / rejected| QoS          | <....+
    |             |<-----------------| reservation  |
    +-------------+                  +--------------+

                Figure 4: Token based three party approach

   The token based three party approach is applicable in environments
   where a previous protocol interaction is used to request
   authorization tokens (or something similar) to assist the
   authorization process at the entity performing the QoS reservation.
   A host contacts the Authorizing entity and obtains an authorization
   token for a requested service prior to sending a QoS reservation
   request.  It includes the authorization token in its reservation
   request and this token is used in the routers along the flow path for
   QoS authorization. (e.g. the authorization token is included in QoS
   AAA messages between the router and the Authorizing entity.)

3.3   QoS authorization considerations

   A QoS authorization application must meet a number of requirements
   applicable to a diverse set of networking environments and services.



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   It should be compliant with different deployment scenarios with
   specific QoS signaling models and security issues.  In addition,
   real-time signaling for QoS provisioning requires a QoS authorization
   application to support flexible and fast authentication and
   authorization methods.  Satisfying these requirements while
   interworking with QoS signaling protocols, a Diameter QoS application
   should accommodate the capabilities of the QoS signaling protocols
   rather than introducing functional requirements on them.  A list of
   requirements for a QoS authorization application is reviewed in
   details in [I-D.alfano-aaa-qosreq].  A short list is provided here:

   Inter-domain support

      In particular, users may roam outside their home network, leading
      to a situation where the network element and authorizing entity
      are in different administrative domains.

   Identity-based Routing

      The QoS AAA protocol MUST route AAA requests to the authorizing
      entity based on the identity information given in the QoS
      signaling protocol.

   Flexible Authentication Support

      The QoS AAA protocol MUST support a variety of different
      authentication protocols for verification of authentication
      information present in QoS signaling messages.

   Making an Authorization Decision

      The QoS AAA protocol MUST exchange sufficient information between
      the authorizing entity and the enforcing entity (and vice versa)
      to compute an authorization decision and to execute this decision.

   Triggering an Authorization Process

      The QoS AAA protocol MUST allow periodic and event triggered
      execution of the authorization process, originated at the
      enforcing entity or even at the authorizing entity.

   Associating QoS Reservations and Application State

      The QoS AAA protocol MUST carry information sufficient for an
      application server to identify the appropriate application session
      and associate it with a particular QoS reservation.





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   Dynamic Authorization

      It MUST be possible for the QoS AAA protocol to push updates
      towards the network element(s) from authorizing entities.

   Bearer Gating

      The QoS AAA protocol MUST allow the authorizing entity to gate
      (i.e., enable/disable) authorized application flows based on e.g.,
      application state transitions.

   Accounting Records

      The QoS AAA protocol MUST define QoS accounting records containing
      duration, volume (byte count) usage information and description of
      the QoS attributes (e.g., bandwidth, delay, loss rate) that were
      supported for the flow.

   Sending Accounting Records

      The network element MUST send accounting records for a particular
      application flow to the authorizing entity for that flow or to
      another entity identified by the authorizing entity.

   Failure Notification

      The QoS AAA protocol MUST allow the network element to report
      failures(such as loss of connectivity due to movement of a mobile
      node or other reasons for packet loss) to the authorizing entity.

   Accounting Correlation

      The QoS AAA protocol MUST support the exchange of sufficient
      information to allow for correlation between accounting records
      generated by the network elements and accounting records generated
      by an application server.

   Interaction with other AAA Applications

      Interaction with other AAA applications such as Diameter Credit
      Control [I-D.ietf-aaa-diameter-cc] and Diameter NASREQ [I-D.ietf-
      aaa-diameter-nasreq] is required for exchange of authorization,
      authentication and accounting information.


   Deployment scenarios for Diameter QoS applicatuion should be divided
   into Authorization_Only or Authentication_and_Authorization,
   depending on the service that a contacted 3-rd party Authorizing



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   entity must provide.  Authorization decisions are based on a provided
   identifier (user or application session) that must be authenticated.

   In cases where authentication is done a priory at the Authorizing
   entity or at the transport plane element by other means, (e.g.,
   collocated application for network access (NASREQ) or authentication
   for secured transport channel establishment used by GIMPS [I-D.ietf-
   nsis-ntlp] in the NSIS, the Authorizing entity is contacted only with
   a request for QoS authorization.  In cases where other authentication
   mechanisms are not present, the Authorizing entity must also
   authenticate the user in order to authorize the QoS request.








































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4.  Diameter QoS Authorization session establishment and management

4.1  Session parties' functional description

   Authorization models supported by this application include 3 parties:
   o  The End-user as the initiator of the QoS signaling session.
   o  QoS policy aware transport plane element(s) (Diameter QoS
      application client).
   o  Authorizing entity (Diameter QoS application server).
   Note that the End-user is an indirect participant in the QoS
   authorization session and is not directly involved in the Diameter
   QoS application session.  The End-user may communicate with the
   Authorizing entity via off-path application level signaling.  The
   End-user communicates with the QoS policy aware network element(s)
   via the QoS signaling protocol.  Considering its indirect role in the
   Diameter QoS application session, we briefly include its functional
   description for clarification purposes.

4.1.1  End-user initiator of the QoS signaling session

   Based on one of the authorization and authentication models, an End-
   user may be involved in application level service negotiation with an
   Application server (Authorizing entity).  At that time the user
   requests are validated against their subscription and as a result the
   Application server issues an authorization token to the End-user for
   the negotiated application service and QoS resources.  An
   authorization token may contain several pieces of information
   pertaining to the authorized application session, but at minimum it
   should contain:
   o  An identifier of the Application server which issued the token,
   o  An identifier of the application session for which it is issued
      and
   o  Authentication data that guarantees the validity of the token.
   A possible structure for the authorization token and the policy
   element carrying it are proposed in [RFC3520], [ETSI-OSP].

   In a different authentication and authorization scenario, which does
   not use a token generated by the authorizing entity, (General 3 party
   approach Figure 3), an End-user MAY initiate a QoS signaling session
   by generating a QoS Reserve message containing the requested QoS
   resource description and additional user identification data, which
   is used also to locate the Authorizing entity.  The Authorizing
   entity should use the provided request and credentials in the
   authentication and authorization process and integrity verification
   of the QoS request.






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4.1.2  QoS policy aware transport plane element functionality

   A request for a QoS reservation received by a Policy aware node,
   initiates a Diameter QoS authorization session.  The Policy aware
   node generates a QoS-Authorization-Request message (QAR) in which it
   maps required objects from the QoS signaling message to Diameter
   AVPs.  Depending on the deployment scenario, information for
   signaling session identification, Authorizing entity identification,
   requested QoS description, End-user identity, authorization token,
   End-user authentication credentials and authentication information
   for QoS objects may all be encapsulated into Diameter AVPs and
   included into the Diameter message send to the Authorizing entity
   (Application server or End-user's home realm).

   The final result of the authorization request is provided in the
   Result-Code AVP of the QoS-Authorization-Answer message (QAA) sent by
   the Authorizing entity.  Description of authorized QoS resources and
   status of the authorized flow (enabled/disabled) are provided in the
   included QoS-Authorization-Resources AVP of the QAA message too.
   Authorized parameters may be installed into the QoS Traffic Control
   function of the QoS policy aware transport plane element (see
   Figure 2).

   Authorization duration information is also provided in the QAA.  A
   number of factors MAY influence the authorized session duration such
   as the user's subscription plan or the method used for QoS
   negotiation and authorization.  Currently authorization duration is
   time-based as specified in [RFC3588].  Before expiration of the
   authorization period, a new QoS-Authorization-Request/Answer message
   exchange should be initiated.  After expiration of the authorization
   lifetime, an explicit request for re-authorization must be sent to
   the transport plane element using a Re-Auth-Request message (RAR).
   Further authorization session maintenance issues are discussed in the
   following section for Re-Authorization and Session termination (see
   Section 4.2 and Section 4.4).

   Authorization duration may also be based on data volume transferred
   on an authorized data flow.

   After successful authorization, session establishment and initiation
   of the data flow, a Diameter accounting session should be established
   between the  transport plane element and an Accounting server.
   Accounting information is reported as specified in [RFC3588] with
   additional extensions specified in a subsequent section for
   Accounting (Section 5).






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4.1.3  Authorizing Entity functionality

   The Diameter QoS application server receives the initial QoS-
   Authorization-Request message (QAR).  It verifies the integrity of
   the included Authorization-Token AVP (if included) (Figure 4).  Based
   on the info in the authorization token and/or the provided user
   identity and credentials, the server determines the authorized QoS
   resources and flow state (enabled/disabled) from a priory negotiated
   resource information or user subscription profile, and includes this
   information in an QoS-Authorization-Answer message (QAA).

   Authorizing entity establishes authorization session state and SHOULD
   save additional information for management of the session (Acc-
   Mulisession-Id, signaling session identifier and authentication data)
   as part of the session state info.  Signaling session identifier (if
   present) SHOULD be used together with the generated
   Acc-Multisession-Id AVP for binding of authorization and accounting
   session information in case of user mobility.  The authentication
   data should be used for verification of the freshness and
   authenticity of subsequent QoS requests.

4.2  QoS authorization session re-authorization

   Client and server-side initiated re-authorizations are considered in
   the design of the Diameter QoS application.  These have impact on the
   interworking between the Diameter and the QoS signaling protocols.

4.2.1  Client-side initiated Re-Authorization

   As described above, the Authorizing entity provides the duration of
   the authorization session as part of the QoS-Authorization-Answer
   message (QAA).  At any time before expiration of this period, a new
   QoS-Authorization-Request message (QAR) may be sent to the
   authorizing entity.  It may be triggered by a reception of a new QoS
   Reserve message which requests modification of the authorized QoS
   reservation state.

4.2.2  Server-side initiated Re-Authorization

   If the client does not re-authorize the session before it expires,
   after expiration of the authorization lifetime, an explicit request
   for re-authorization is sent from the Authorizing entity to the
   transport plane element with an Re-Auth-Request message (RAR).  This
   message should trigger a notification QoS signaling message sent to
   the End-user who is expected to initiate a refreshing QoS Reserve
   message containing a description of the refreshed QoS resources.
   Reception of this message at the QoS policy aware node will trigger
   QoS-Authorization-Request message (QAR), which eventually re-



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   authorizes the authorization session and extend its lifetime.

   At any time during the QoS authorization session the Authorizing
   server MAY send Re-Auth-Request message (RAR).  The transport plane
   element MUST respond with Re-Auth-Answer message (RAA) and send a
   notification QoS signaling message to the End-user, which will
   trigger the previously described process of QoS state refresh and re-
   authorization.

4.3  Server-side initiated QoS parameter provisioning

   The Authorizing entity (Home Server or Application Server) is enabled
   to update installed QoS parameters and flow state at the QoS aware
   transport plane elements by sending a QoS-Install Request message
   (QIR).  Transport elements MUST apply the updates and respond with an
   QoS-Install Answer message (QIA).  An example application of this
   functionality would be updating of the flow status of an established
   QoS reservation due to a change of the application service session.
   Early initial QoS parameter installation (prior to a request from a
   transport plane element) is allowed.  Early installation requires
   availability of specific information to the Authorizing entity, e.g.,
   identity of the node that should be contacted and identification of
   the flow (filter specifications) for which the QoS reservation is
   established.

4.4  Session Termination

4.4.1  Client-side initiated session termination

   A QoS authorization session MAY be terminated from the client side by
   sending a Session-Termination-Request message (STR) to the server.
   This is a Base Diameter protocol functionality and it is defined in
   [RFC3588].  Session termination can be caused by a QoS signaling tear
   down message or via a loss of bearer report.  After a successful
   termination of the authorization session, final accounting messages
   should be exchanged.

4.4.2  Server-side initiated session termination

   At anytime during a session the Authorizing server may send an Abort-
   Session-Request message (ASR) to the transport plane element
   [RFC3588].  Possible reasons are insufficient accounting credits or
   session termination at the application layer.  This results in
   termination of the authorization session, release of the reserved
   resources at the transport plane node and sending appropriate QoS
   signaling notification to other transport plane elements aware of the
   signaling session.  Final accounting message exchanges must also
   occur.



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5.  Accounting

   The Diameter QoS application presented in this document reuses
   Diameter Accounting as defined in [RFC3588].  A definition of new
   Accounting attributes is necessary, but left for further study.

   After a successful QoS authorization and start of the transport plane
   flow, the transport plane element starts the corresponding accounting
   session by sending an Accounting-Request message (ACR).  The message
   SHOULD contain necessary attributes to facilitate the binding of the
   current accounting session to the reported authorization session.
   The Accounting server replies to a successfully received Accounting-
   Request message (ACR) with an Accounting-Answer message (ACA), which
   MAY contain instructions for handling of the accounting session,
   e.g., the Accounting-Interim-Interval AVPs.

   After every successful re-authorization procedure the transport plane
   element SHOULD initiate an accounting message exchange.

   After successful session termination the transport plane element MUST
   initiate a final exchange of accounting messages with the Accounting
   server.





























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6.  Diameter QoS authorization application Messages

   The Diameter QoS Application requires the definition of new mandatory
   AVPs and Command-codes [RFC3588].  Four new Diameter messages are
   defined along with Command-Codes whose values MUST be supported by
   all Diameter implementations that conform to this specification.


   Command-Name                  Abbrev.        Code      Reference
   QoS-Authz-Request              QAR           [TBD]     Section 6.1
   QoS-Authz-Answer               QAA           [TBD]     Section 6.2
   QoS-Install-Request            QIR           [TBD]     Section 6.3
   QoS-Install-Answer             QIA           [TBD]     Section 6.4

   In addition, the following Diameter Base protocol messages are used
   in the Diameter QoS application:


   Command-Name                  Abbrev.        Code      Reference
   Accounting-Request             ACR            271       RFC 3588
   Accounting-Request             ACR            271       RFC 3588
   Accounting-Answer              ACA            271       RFC 3588
   Re-Auth-Request                RAR            258       RFC 3588
   Re-Auth-Answer                 RAA            258       RFC 3588
   Abort-Session-Request          ASR            274       RFC 3588
   Abort-Session-Answer           ACA            274       RFC 3588
   Session-Term-Request           STR            275       RFC 3588
   Session-Term-Answer            STA            275       RFC 3588

   Diameter nodes conforming to this specification MAY advertise support
   by including the value of TBD (TBD) in the Auth-Application-Id or the
   Acct-Application-Id AVP of the Capabilities-Exchange-Request and
   Capabilities-Exchange-Answer commands [RFC3588].

   The value of TBD (TBD) MUST be used as the Application-Id in all QAR/
   QAA and QIR/QIA commands.

   The value of TBD (TBD) MUST be used as the Application-Id in all ACR/
   ACA commands, because this application defines new, mandatory AVPs
   for accounting.

   The value of zero (0) SHOULD be used as the Application-Id in all
   STR/STA, ASR/ASA, and RAR/RAA commands, because these commands are
   defined in the Diameter base protocol and no additional mandatory
   AVPs for those commands are defined in this document.






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6.1  QoS-Authorization Request (QAR)

   The QoS-Authorization-Request message (QAR) indicated by the Command-
   Code field set to TDB (TBD) and 'R' bit set in the Command Flags
   field is used by transport plane elements to request quality of
   service related resource authorization for a given flow.

   The message MUST carry information for signaling session
   identification, Authorizing entity identification, requested QoS
   description, and End-user identity.  In addition, depending on the
   deployment scenario, an authorization token, End-user authentication
   credentials and QoS objects authentication information should be
   included.

   The message format is defined as follows:


   <QoS-Request> ::= < Diameter Header: XXX, REQ, PXY >
                     < Session-Id >
                     { Auth-Application-Id }
                     { Origin-Host }
                     { Origin-Realm }
                     { Destination-Realm }
                     { Auth-Request-Type }
                     [ Destination-Host ]
                     [ Signaling-Session-Id ]
                     [ Authorization-Token ]
                     [ User-Name ]
                     [ QoS-Authorization-Resources ]
                     [ QoS-Authentication-Data ]
                     [ CC-Corelation-Id ]
                     [ Acc-Multisession-Id ]
                  *  [ AVP ]


6.2  QoS-Authorization Answer

   The QoS-Authorization-Answer message (QAA), indicated by the Command-
   Code field set to TBD (TBD) and 'R' bit cleared in the Command Flags
   field is sent in response to the QoS-Authorization-Request message
   (QAR).  If the QoS authorization request is successfully authorized,
   the response will include the AVPs to allow authorization of the QoS
   resources as well as accounting and transport plane gating
   information.

   The message format is defined as follows:





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   <QoS-Answer> ::= < Diameter Header: XXX, PXY >
                    < Session-Id >
                    { Auth-Application-Id }
                    { Auth-Request-Type }
                    { Result-Code }
                    { Origin-Host }
                    { Origin-Realm }
                    [ Signaling-Session-Id ]
                    [ QoS-Authorization-Resources ]
                    [ Acc-Multisession-Id ]
                    [ Session-lifetime ]
                    [ Authz-Session-Lifetime ]
                    [ Authz-Grace-Period ]
                    [ Authz-Session-Volume ]
                 *  [ AVP ]


6.3  QoS-Install Request

   The QoS-Install Request message (QIR), indicated by the Command-Code
   field set to TDB (TBD) and 'R' bit set in the Command Flags field is
   used by Authorizing entity to install or update the QoS parameters
   and the flow state of an authorized flow at the transport plane
   element.

   The message MUST carry information for signaling session
   identification or identification of the flow to which the provided
   QoS rules apply, identity of the transport plane element, description
   of provided QoS parameters, flow state and duration of the provided
   authorization.

   The message format is defined as follows:


   <QoS-Install-Request> ::= < Diameter Header: XXX, REQ, PXY >
                             < Session-Id >
                             { Auth-Application-Id }
                             { Origin-Host }
                             { Origin-Realm }
                             { Destination-Realm }
                             { Auth-Request-Type }
                             [ Destination-Host ]
                             [ Signaling-Session-Id ]
                             [ QoS-Authorization-Resources ]
                             [ Session-Timeout ]
                             [ Authz-Session-Lifetime ]
                             [ Authz-Grace-Period ]
                             [ Authz-Session-Volume ]



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                          *  [ AVP ]


6.4  QoS-Install Request

   The QoS-Install Answer message (QAA), indicated by the Command-Code
   field set to TBD (TBD) and 'R' bit cleared in the Command Flags field
   is sent in response to the QoS-Install Request message (QIR) for
   confirmation of the result of the installation of the provided QoS
   reservation instructions.

   The message format is defined as follows:


   <QoS-Install-Answer> ::= < Diameter Header: XXX, REQ, PXY >
                            < Session-Id >
                            { Auth-Application-Id }
                            { Origin-Host }
                            { Origin-Realm }
                            { Auth-Request-Type }
                            { Result-Code }
                            [ Signaling-Session-Id ]
                            [ QoS-Authorization-Resources ]
                         *  [ AVP ]



























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7.   Diameter QoS Authorization Application AVPs

   Each of the AVPs identified in the QoS-Authorization-Request/Answer
   and QoS-Install-Request/Answer messages and the assignment of their
   value(s) is given in this section.

7.1  Diameter Base Protocol AVPs

   The Diameter QoS application uses a number of session management
   AVPs, defined in the Base Protocol ([RFC3588]).


   Attribute Name                AVP Code     Reference [RFC3588]
   Origin-Host                   264             Section 6.3
   Origin-Realm                  296             Section 6.4
   Destination-Host              293             Section 6.5
   Destination-Realm             283             Section 6.6
   Auth-Application-Id           258             Section 6.8
   Result-Code                   268             Section 7.1
   Auth-Request-Type             274             Section 8.7
   Session-Id                    263             Section 8.8
   Authz-Lifetime                291             Section 8.9
   Authz-Grace-Period            276             Section 8.10
   Session-Timeout                27             Section 8.13
   User-Name                       1             Section 8.14

   Some of the listed AVPs require definition and assignment of
   additional values which is described here:

   Auth-Application-Id AVP

      The Auth-Application-Id is assigned by IANA to Diameter
      applications.  The value of the Auth-Application-Id for the
      Diameter QoS application is TBD (TBD).

   Result-Code AVP

      The Result-Code AVP indicates if a particular request was
      completed successfully.  Definition of QoS authorization specific
      Result-Code values is for further study.  (TBD)


7.2  Credit Control application AVPs

   The process of QoS authorization and accounting of the consumed
   reserved resources is closely related to credit control over the
   services provided to a user.  An option for correlating of the
   accounting records for the different provided services should be



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   available.  For this purpose, the Diameter QoS application should
   support appropriate AVPs defined by the Diameter Credit Control
   document [I-D.ietf-aaa-diameter-cc].

   CC-Correlation-Id AVP

      The CC-Correlation-ID AVP (AVP code TBD) is of type OcterString
      and contains information to correlate accounting data generated
      for different components of the service, e.g. transport and
      application level.

7.3  Authentication/Authorization AVPs

   Authentication and authorization is essential for the Diameter QoS
   application.  Flexibility is desired for deployment into
   infrastructures with different security features and usage of
   authentication and authorization applications such as [I-D.ietf-aaa-
   eap] and [I-D.ietf-aaa-diameter-nasreq].  Multiple methods specified
   in these applications MIGHT be reused.  Alternatively autonomous and
   QoS-specific authentication methods may be supported depending on the
   features of the QoS signaling protocols.  Therefore, a number of AVPs
   of related Diameter applications can be used.

   The three party general approach (see Figure 3) utilizes an EAP based
   authentication and session key exchange which requires the support of
   AVPs defined in the Diameter-EAP application [I-D.ietf-aaa-eap].  The
   details of the required attributes for authentication and
   authorization is for further study.

7.4  Accounting AVPs

   The Diameter QoS application uses Diameter Accounting and accounting
   AVPs as defined in Section 9 of [RFC3588].  Additional description of
   the usage of some of them in QoS authorization context is provided:

   Acc-Multisession-ID

      Acc-Multisession-ID AVP (AVP Code 50) SHOULD be used to link
      multiple accounting sessions together, allowing the correlation of
      accounting information.  This AVP MAY be returned by the Diameter
      server in a QoS-Authorization-Answer message (QAA), and MUST be
      used in all accounting messages for the given session.

7.5  Diameter QoS Application Defined AVPs

   This section defines the Quality of Service AVPs that are specific to
   the Diameter QoS application and MAY be included in the Diameter QoS
   application messages.  Unlike the approach followed with RSVP (see



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   [RFC2749]), where the entire RSVP message is encapsulated into a COPS
   message, only the relevant fields SHOULD be included.  This approach
   avoids a certain overhead of transmitting fields which are irrelevant
   for the AAA infrastructure.  It keeps implementations simpler and it
   allows the reuse of other Diameter AVPs.

   The following table describes the Diameter AVPs in the QoS
   Application, their AVP code values, types, possible flag values, and
   whether the AVP MAY be encrypted.


                                             |    AVP Flag rules      |
                                             |----+---+----+-----|----+
                      AVP  Section           |    |   |SHLD| MUST|    |
    Attribute Name    Code Defined Data Type |MUST|MAY| NOT|  NOT|Encr|
   ------------------------------------------+----+---+----+-----+----+
   Signaling-Session  TBD    7.5  Unsigned32 | M  | P |    |  V  | Y  |
     -Id                                     |    |   |    |     |    |
   Flow-ID            TBD    7.5  Unsigned32 | M  | P |    |  V  | Y  |
   QoS-Filter-Rule    TBD    7.5  QoSFltrRule| M  | P |    |  V  | Y  |
   SPI                TBD    7.5  Unsigned32 | M  | P |    |  V  | Y  |
   QoS-Flow-State     TBD    7.5  Enumerated | M  | P |    |  V  | Y  |
   IND-Flow           TBD    7.5  Grouped    | M  | P |    |  V  | Y  |
   Flows              TBD    7.5  Grouped    | M  | P |    |  V  | Y  |
   QSPEC              TBD    7.5  OctetString| M  | P |    |  V  | Y  |
   QoS-Auth           TBD    7.5  Grouped    | M  | P |    |  V  | Y  |
     -Resources                              |    |   |    |     |    |
   QoS-Auth-Data      TBD    7.5  Grouped    | M  | P |    |  V  | Y  |
   Authorization      TBD    7.5  OctetString| M  | P |    |  V  | Y  |
     -Token                                  |    |   |    |     |    |
   Auth-Session       TBD    7.5  Unsigned32 | M  | P |    |  V  | Y  |
     -Volume                                 |    |   |    |     |    |
   ------------------------------------------+----+---+----+-----+----+

   Signaling-Session-ID

      Signaling-Session-ID AVP (AVP Code TBD) is of type Unsigned32 and
      contains a copy of the QoS signaling session identifier, which is
      a unique identifier of the QoS signaling session that in NSIS case
      remains unchanged for the duration of the session.

   Flow-ID

      The Flow-ID AVP (AVP Code TBD) is of type Unsigned32 and contains
      identifier of an IP flow.






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   QoS-Filter-Rule

      The QoS-Filter-Rule AVP (AVP Code TBD) is of type QoSFilterRule
      and provides filter rules for a packet flow of the user.  It would
      be used in case of the explicit rule provisioning initiated by the
      Authorizing server, too.

   SPI

      The SPI AVP (AVP Code TBD) is of type Unsigned32 and extends the
      QoS-Filter-Rule AVP to support IPsec protected traffic.

   QoS-Flow-State

      The QoS-Flow-State AVP (AVP Code TBD) is of type Enumerated.  It
      gives an indication by the Authorizing entity how the flow MUST be
      treated.  When included in a QAA message, it is instructions to
      the transport plane control element with regard to the state to
      which the flow should be set.  The supported values are:


   0  Open     - Enable the transport plane service, for which
                 the signaling is done
   1  Close    - Disable the transport plane service
   2  Maintain - Current state (enabled/disabled) of the transport
                 plane service is maintained


      The QoS-Flow-State is an optional AVP.  When not included in a QAA
      response, the default behaviour is to immediately allow the flow
      of packets (Open).


   IND-Flows

      The IND-Flows AVP (AVP Code TBD) is of type Grouped and specifies
      IP Flows via their flow identifiers and filter-rule.


   IND-Flows ::= <AVP Header>
                 [Flow-Id]
                 [QoS-Filter-Rule]
           [0-1] [SPI]
           [0-1] [QoS-Flow-State]







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   Flows

      The Flows AVP (AVP Code TBD) is of type Grouped and contains all
      the individual flows that receive the same QoS specified in the
      included QSPEC.


   Flows    ::= < AVP Header: XXX >
          [1+]* [ IND-Flows ]

   QSPEC

      The QSPEC AVP (AVP Code TBD) is of type OctetString and contains
      QoS parameter information.  Description format is taken from QoS
      NSLP Qspec template, which is expected to cover all present QoS
      description methods [I-D.ietf-nsis-qspec].


   QoS-Authorization-Resources

      The QoS-Auth-Resources AVP (AVP Code TBD) is of type Grouped and
      includes description of the resources that have been requested by
      the user or authorized by the application server for a particular
      QoS request.  More than one MAY be included into a message.


   QoS-Auth-Resources ::= < AVP Header: XXX >
                   [0-1]  [ Signaling-Session-ID ]
                   [0-1]* [ Flows ]
                     [1]  [ QSPEC ]
                   [0-1]  [ QoS-Flow-State ]


      Included QoS-Flow-State AVP SHOULD be overwritten by any included
      QoS-Flow-State AVPs specified for the individual flows.


   QoS-Authentication-Data

      The QoS-Authentication-Data AVP (AVP Code TBD) is of type Grouped
      and contains data used for End-user authentication and integrity
      protection of the QoS signaling messages.  (TBD)









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   Authorization-Token

      The Authorization-Token AVP (AVP Code TBD) is of type OctetString
      and SHOULD contain application session authorization token such as
      the one defined in [RFC3520] (TBD)


   Authz-Session-Volume

      The Authz-Session-Volume AVP (AVP Code TBD) is of type Unsigned32
      and contains the maximum data volume authorized by the Authorizing
      entity.







































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8.  Examples

   This section illustrates a general message flow of QoS authorization
   session establishment(Figure 17) and interworking with NSIS
   (Figure 18).

   Figure 17 shows the protocol exchange between the Diameter client and
   the Diameter server.  An incoming QoS reservation request received at
   the transport plane element invokes sending of QoS-Authorization-
   Request message {QAR) to the Authorization server.  Server replies
   with QoS-Authorization-Answer message (QAA), which grants reservation
   of certain resources.  After the successful exchange of authorization
   QAR/QAA messages, the transport plane node starts an accounting
   session by sending an Accounting-Request message (ACR).  The server
   replies with an Accounting-Answer message (ACA) that MAY include
   instructions for further handling of the accounting session, such as
   the Acc-Interim-Period AVP.  A possible client-side re-authorization
   caused by expiration of the authorization lifetime initiates a QAR/
   QAA message exchange.  After successful re-authorization an
   accounting message ACR SHOULD be sent.  The server relpies to the ACR
   with an ACA message.  In this example, the Application server
   initiates a session termination.  To do this it sends an Abort-
   Session-Request message (ASR).  The client responds with an ASA
   message and a Session-Termination-Request message {STR).  After
   receiving the STA message sent by the server, which finalizes the
   authorization session, the client sends final accounting information
   with the ACR message.  The ACA message from the server also
   terminates the accounting session.























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              Router(Diameter client)               Diameter Server
   -----------> |                                            |
   QOS          | QoS-Request                                |
   reservation  |------------------------------------------->|
   request      |                                            |
                |              QoS-Answer/QoS-Auth-Res./     |
                |<-------------------------------------------|
                |                                            |
    Start       |Acc-Request/Start,QoS Acc-Msess-ID.../      |
    Accounting  |------------------------------------------->|
                |    Acc-Answer/...Acc-Interim-Period.../    |
                |<-------------------------------------------|
                |                                            |
   Authorization|                                            |
   LifeTime     |                                            |
   Expires:     |                                            |
   Re-          | QoS-Request                                |
   Authorization|------------------------------------------->|
                |       QoS-Answer/QoS-Auth-Res./            |
                |<-------------------------------------------|
                | Acc-Request/Interim, Acc-Msess-ID.../      |
                |------------------------------------------->|
                |    Acc-Answer/...Acc-Interim-Period.../    |
                |<-------------------------------------------|
                             .....................
                |                                            | Session
                |                                            |   Term.
                |                                            |initiate
                |                                            |by Server
                |        Abort-Session-Request               |<--------
                |<-------------------------------------------|
                | Abort-Session-Answer                       |
                |------------------------------------------->|
                | Session-Termination-Request                |
                |------------------------------------------->|
                |             Session-Termination-Answer     |
                |<-------------------------------------------|
   Accounting   |    Acc-Request/Final,Acc-Msess-ID.../      |
      end       |------------------------------------------->|
                |               Acc-Answer /Final,.../       |
                |<-------------------------------------------|

                Figure 17: Diameter QoS Application Session

   Figure 18 shows the interaction between NSIS, application layer
   signaling (e.g., SIP) and the Diameter QoS application.  First, a
   service request is sent from the client to the application server.
   In response, for example, it returns an authorization token to bind



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   the application layer signaling exchange to the subsequent NSIS
   signaling session.  The authorization token is attached to the NSIS
   signaling message and the message itself is intercepted by the first
   NSIS QoS NSLP node.  This router then needs to authorize the QoS
   request and delegates this responsibility to the Diameter QoS
   application.  This type of authorization model is described in
   Section 1 and in Section 3.6 of [I-D.ietf-nsis-qos-nslp].  The
   Diameter QoS Authorization Request (QAR), which includes the
   authorization token and QoS information, is forwarded to the
   administrative domain of the application domain for verification.  As
   a response, the authorization decision is returned with the Diameter
   QoS Answer (QAA) message.  Finally, the NSIS QoS NLP aware router
   acts as an enforcement point.  If the authorization decision provided
   with the QAA message was successful then the NSIS signaling message
   is forwarded further along the path.  Otherwise, the QoS NSLP returns
   an error message to the end host (such as 'Authorization denied').



































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                Diameter QoS
                Application
                Enabled Router                Application
                Enforcement Pt                  Server
     Application                    +
     Client                Domain 1 + Domain 2
          |            |            +             |
          |          Service Request (QoS)        |
          +------------+------------+------------->
          |            |            +             |
          |            |            +             |
          |      Service Response (QoS', Token)   |
          <------------+------------+-------------+
          |            |            +             |
          |            |            +             |
          |NSIS (Token)|            +             |
          +------------>            +             |
          |            |            +             |
          |            |           -+--           |
          |            |QAR(Token)- +  -QAR(Token)|
          |            +--------/>  +  --\-------->
          |            |       /    +     \       |
          |            |       /    +     \       |
          |            |      |     +      |      |
          |            | QAA(QoS)   +   QAA(QoS)  |
          |            <------+---  +  <---+------+
          |            |      |     +      |      |
          |            |      |  Diameter  |      |
          |            |       \ Network  /       |
          |            |       \    +     /       |
          |            |        \   +    /        |
          |      Authorization   \- +  -/         |
          |      Enforcement       -+--           |
          |      Decision           +             |
          |            |            +             |
          |            |            +             |
          |  Allow or Terminate Flow              |
          <-----------+*+------------------------->
          |            |            +             |
          |            |            +             |

      Figure 18: Message flow with NSIS and Diameter QoS Application

   A future version of this document will describe scenarios with other
   authorization models.






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9.  Security Considerations

   This document describes a mechanism for performing authorization of a
   QoS reservation at a third party entity.  Therefore, it is necessary
   the QoS signaling protocol to forward the necessary information to
   the backend AAA server.  This functionality is particularly useful in
   roaming environments where the authorization decision is most likely
   provided at an entity where the user can be authorized, such as in
   the home realm.  To provide proper authorization, authentication
   might be necessary at least for the generic third party model
   (described in Section 3.6 of [I-D.ietf-nsis-qos-nslp]).  Please note
   that authentication is not provided to the QoS NSLP router but
   torwards the users home network.  The concept of an authorization
   token based third party approach is also described in the same
   document.  The impact of the existence of different authorization
   models is (with respect to this Diameter QoS application) the ability
   to carry different authentication and authorization information.

   Further discussions on the authorization handling for QoS signaling
   protocols is available with [I-D.tschofenig-nsis-aaa-issues] and
   [I-D.tschofenig-nsis-qos-authz-issues].






























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10.  Contributors


















































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11.  Acknowledgements

   Add your name here.
















































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12.  Open Issues

   During our work on this document we identified the following open
   issues:

   o  This Diameter QoS application can reuse a number of other Diameter
      applications.  This is a big advantage over other approaches.
      This interaction and a list of useful attributes needs to be
      collected and described.  This aspect is for further study.

   o  The NSIS group is currently working on QoS models.  As soon as
      results are available it is feasible to incorporate them into this
      Diameter application to build a complete solution for QoS
      signaling which uses a backend infrastructure.

   o  Several authorization models have been described in [I-D.ietf-
      nsis-qos-nslp].  Section 8 currently addresses only the third
      party approach using authorization tokens.  Further work is needed
      to describe the details of a generic three party scenario.

   o  Section 4.2 raises the question of a re-authorizing capability for
      the Diameter application.  The authors think that such a re-
      authorization capability would be desirable (e.g., using with the
      RAR/RAA message exchange).  Note that it would require the
      transport plane signaling protocol (for example RSVP or NSIS) to
      support network-initiated re-auth, which might not always be in
      place.  There should be a failure code for the case where the
      underlying transport plane signaling protocol does not support it.

   o  The terminology regarding the 'transport plane node' needs further
      refinement.




















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13.  References

13.1  Normative References

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

   [RFC3588]  Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J.
              Arkko, "Diameter Base Protocol", RFC 3588, September 2003.

13.2  Informative References

   [ETSI-OSP]
              European Telecommunications Standards Institute,
              "Telecommunications and Internet Protocol Harmonization
              Over  Networks (TIPHON); Open Settlement Protocol (OSP)
              for Inter-domain  pricing, authorization, and usage
              exchange", TS 101 321.

   [I-D.alfano-aaa-qosreq]
              Alfano, F., "Requirements for a QoS AAA Protocol",
              draft-alfano-aaa-qosreq-01 (work in progress),
              October 2003.

   [I-D.ietf-aaa-diameter-cc]
              Mattila, L., Koskinen, J., Stura, M., Loughney, J., and H.
              Hakala, "Diameter Credit-control Application",
              draft-ietf-aaa-diameter-cc-06 (work in progress),
              August 2004.

   [I-D.ietf-aaa-diameter-nasreq]
              Calhoun, P., Zorn, G., Spence, D., and D. Mitton,
              "Diameter Network Access Server Application",
              draft-ietf-aaa-diameter-nasreq-17 (work in progress),
              July 2004.

   [I-D.ietf-aaa-diameter-sip-app]
              Garcia-Martin, M., "Diameter Session Initiation Protocol
              (SIP) Application", draft-ietf-aaa-diameter-sip-app-07
              (work in progress), March 2005.

   [I-D.ietf-aaa-eap]
              Eronen, P., Hiller, T., and G. Zorn, "Diameter Extensible
              Authentication Protocol (EAP) Application",
              draft-ietf-aaa-eap-10 (work in progress), November 2004.

   [I-D.ietf-nsis-ntlp]
              Schulzrinne, H. and R. Hancock, "GIMPS: General Internet



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              Messaging Protocol for Signaling", draft-ietf-nsis-ntlp-06
              (work in progress), May 2005.

   [I-D.ietf-nsis-qos-nslp]
              Bosch, S., Karagiannis, G., and A. McDonald, "NSLP for
              Quality-of-Service signaling", draft-ietf-nsis-qos-nslp-06
              (work in progress), February 2005.

   [I-D.ietf-nsis-qspec]
              Ash, J., "QoS-NSLP QSPEC Template",
              draft-ietf-nsis-qspec-05 (work in progress), July 2005.

   [I-D.tschofenig-nsis-aaa-issues]
              Tschofenig, H., "NSIS Authentication, Authorization and
              Accounting Issues", draft-tschofenig-nsis-aaa-issues-01
              (work in progress), March 2003.

   [I-D.tschofenig-nsis-qos-authz-issues]
              Tschofenig, H., "QoS NSLP Authorization Issues",
              draft-tschofenig-nsis-qos-authz-issues-00 (work in
              progress), June 2003.

   [RFC2210]  Wroclawski, J., "The Use of RSVP with IETF Integrated
              Services", RFC 2210, September 1997.

   [RFC2327]  Handley, M. and V. Jacobson, "SDP: Session Description
              Protocol", RFC 2327, April 1998.

   [RFC2749]  Herzog, S., Boyle, J., Cohen, R., Durham, D., Rajan, R.,
              and A. Sastry, "COPS usage for RSVP", RFC 2749,
              January 2000.

   [RFC3313]  Marshall, W., "Private Session Initiation Protocol (SIP)
              Extensions for Media Authorization", RFC 3313,
              January 2003.

   [RFC3520]  Hamer, L-N., Gage, B., Kosinski, B., and H. Shieh,
              "Session Authorization Policy Element", RFC 3520,
              April 2003.

   [RFC3521]  Hamer, L-N., Gage, B., and H. Shieh, "Framework for
              Session Set-up with Media Authorization", RFC 3521,
              April 2003.








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Authors' Addresses

   Frank M. Alfano
   Lucent Technologies
   1960 Lucent Lane
   Naperville, IL  60563
   USA

   Phone: +1 630 979 7209
   Email: falfano@lucent.com


   Peter J. McCann
   Lucent Technologies
   1960 Lucent Lane
   Naperville, IL  60563
   USA

   Phone: +1 630 713 9359
   Email: mccap@lucent.com


   Hannes Tschofenig
   Siemens
   Otto-Hahn-Ring 6
   Munich, Bavaria  81739
   Germany

   Email: Hannes.Tschofenig@siemens.com
   URI:   http://www.tschofenig.com


   Tseno Tsenov
   Siemens
   Otto-Hahn-Ring 6
   Munich, Bavaria  81739
   Germany

   Email: tseno.tsenov@mytum.de












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