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   Network Working Group                              F. Adrangi, Intel
   INTERNET DRAFT                 P. Congdon, C. Black, Hewlett Packard
   Category: Informational                 A. Lior, Bridgewater Systems
   Expires: Aug 2004                             F. Bari, AT&T Wireless
                                                            Feb 8, 2004

                      Access Network Bandwidth Capability
                draft-adrangi-radius-bandwidth-capability-00.txt


   Status of this Memo

        This document is an Internet-Draft and is in full conformance
        with all provisions of Section 10 of RFC2026.

        Internet-Drafts  are  working  documents  of  the  Internet
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        Drafts as reference material or to cite them other than as "work
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        http://www.ietf.org/ietf/1id-abstracts.txt

        The list of Internet-Draft Shadow Directories can be accessed at
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   Abstract

      This  document  describes  network  bandwidth  parameters  and  a
      protocol framework within which the parameters can be exchanged
      between an Access Network (AN) and a Home Service Network (HSN)
      in order to determine the average minimum and maximum bandwidth
      for both ingress and egress traffic that should be allocated by
      the AN for the duration of an authorized client session.













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   Table of Contents

   1. Introduction....................................................2
   1.2 Requirements language..........................................3
   1.3 Terminology....................................................3
   2. Overview........................................................3
   2.1 Bandwidth Parameters...........................................3
   2.1.1 Ingress Minimum Bandwidth....................................3
   2.1.2 Ingress Maximum Bandwidth....................................4
   2.1.3 Egress Minimum Bandwidth.....................................4
   2.1.4 Egress Maximum Bandwidth.....................................4
   2.2 Protocol.......................................................4
   2.2.1 Static Bandwidth Allocation..................................5
   2.2.2 Dynamic Bandwidth Allocation.................................7
   2.2.2.1 Push Method................................................7
   2.2.2.2 Pull Method................................................8
   3. Operations.....................................................10
   4. Attribute Format/Syntax........................................10
   5.  Table of Attribute(s).........................................12
   6. Attribute Usage Examples.......................................12
   7. IANA Considerations............................................13
   8. Security Considerations........................................13
   9. Acknowledgements...............................................13
   10. References....................................................13
   AuthorsÆ Addresses................................................14



   1. Introduction

     The bandwidth that a user is authorized within an Access Network
     (AN) can be a result of the AN bandwidth capabilities based on its
     architecture and access technology, and the type of user
     subscription to the home network (e.g., gold, silver, bronze user
     types).

     This document describes a simple protocol framework that enables
     an Access Network (AN) to advertise its network bandwidth
     capabilities that it can allocate for a given AN client connection
     to the clientÆs Home Service Network (HSN).  And, it also enables
     the HSN to indicate its selection of the desired network bandwidth
     capabilities for the client connection to the AN.

     User bandwidth can be determined during initial authentication
     authorization of the session.  It is also desirable to change the
     bandwidth for the mid-session.  For example, the user may want to
     purchase additional bandwidth to download a large file.  This
     document enables operators to dynamically modify the bandwidth
     allocation for a session.



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     This document defines a new AAA attribute used for exchanging
     network bandwidth parameters between the AN and the HSN, to
     determine the average minimum and maximum bandwidth for both
     ingress and egress traffic that an AN should allocate for the
     duration of an authorized client session.  This attribute is also
     used for reporting the allocated bandwidth in accounting records.
     The attribute is described for RADIUS [1].

   1.2 Requirements language

      In this document, several words are used to signify the
      requirements of the specification.  These words are often
      capitalized.  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 [RFC2119].

   1.3 Terminology

      Access Network (AN)
          The network that provides wired or wireless connectivity
          to the Internet for clients (or stations) present in the
          local access area. This MAY be in a separate security and
          routing domain with respect to the Home Service Network or a
          Mediating Network.

      Home Service Network (HSN)
          The network providing the service and therefore maintaining
          the direct relationship to its users and subscribers. All AAA
          functions are ultimately performed by the HSN.

      RADIUS server
         ôThis is a server which provides for
         authentication/authorization via the protocol described in
         [1], and for accounting as described in [6].ö  It is deployed
         in the PWLAN AN, MN, and HSN.

   2. Overview

     This section describes the bandwidth parameters and the protocol
     by which these parameters are exchanged between an AN and a HSN.

   2.1 Bandwidth Parameters

      Bandwidth parameters describe the average minimum and maximum
      data rates (for both ingress and egress traffic) for a client
      connection within an AN.  There are four bandwidth parameters,
      which are described in the following subsections.

   2.1.1 Ingress Minimum Bandwidth


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        The ingress minimum bandwidth parameter indicates the average
        minimum ingress data rate that an AN will try to provide to an
        authorized user.  This value is a target, rather than a
        guarantee.

   2.1.2 Ingress Maximum Bandwidth

        The ingress maximum bandwidth parameter indicates the average
        maximum ingress data rate that an AN can allow to an authorized
        user.

   2.1.3 Egress Minimum Bandwidth

        The minimum egress bandwidth parameter indicates the average
        minimum egress data rate that an AN will try to provide to an
        authorized user.

   2.1.4 Egress Maximum Bandwidth

        The maximum egress bandwidth parameter indicates the average
        maximum data rate that an AN can allow to an authorized user.

   2.2 Protocol

      Two protocols are described.  One protocol is used to allocate
      bandwidth when a service is initiated (referred to as Static
      Bandwidth Allocation); the other protocol describes how to change
      bandwidth attribute dynamically that is, mid session (referred to
      as Dynamic Bandwidth Allocation).

      Both protocols exchange bandwidth parameters using the various
      RADIUS messages, and they are comprised of three phases:
      bandwidth Advertisement, Selection, and Confirmation.

      Bandwidth Advertisement:

         MAY be sent in Access-Request packet from the AN to the HSN
         and conveys possible/available bandwidth parameters that can
         be allocated for an the AN client connection to the HSN by the
         AN.  Advertisements are optional.

      Bandwidth Selection:

         MAY be sent in Access-Accept packet and Change of
         Authorization (COA) messages.  Selection conveys the desired
         bandwidth for the AN Client connection to the AN by the HSN.

      Bandwidth Confirmation:

         If Bandwidth Selection is received and enforced, It MUST be
         sent in Accounting-Request packets.  Confirmation indicates

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         that the desired bandwidth parameters specified by a HSN are
         being enforced by the AN.


      Bandwidth Attribute (BA), defined in section 3, is used to carry
      the Bandwidth Advertisement, Selection, Confirmation in various
      RADIUS packets.

      An Advertisement, Selection, Confirmation is said to be valid if
      it contains the four aforementioned bandwidth parameters and the
      minimum bandwidth rate values for ingress and egress traffic MUST
      be equal or less than their corresponding maximum bandwidth rate
      values.

      If a Selection is sent in response to an Advertisement, for the
      Selection to be considered valid, then the bandwidth parameters
      in the Selection MUST NOT exceed the corresponding bandwidth
      parameters in the Advertisement.

      The following subsections describe static and dynamic bandwidth
      allocation.

   2.2.1 Static Bandwidth Allocation

        Static bandwidth allocation is preformed during the initial
        session authentication / authorization.

        The following diagram shows the protocol interaction between
        the AN and the HSN for determining network bandwidth rates that
        an AN needs to allocate for an AN client connection.






















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      AN Client      AN Device + AAA client       HSN + AAA Server

          |                  |                              |
          |                  |                              |
          | Authentication   |                              |
          | Phase Begin      |                              |
          |----------------->|        Access-Request        |
          |                  |            +                 |
          |                  |    BA for Advertisement      |
          |                  |----------------------------->|
          |                  |                              |
          |<<More Authentication/Authorization Exchanges>>  |
          |                  |                              |
          |                  |                              |
          |                  |<-----------------------------|
          |                  |        Access-Accept         |
          | Authentication   |            +                 |
          |    Accept        |      BA for Selection        |
          |<-----------------|                              |
          |                  |                              |
          |                  |                              |
          |                  |       Accounting Request     |
          |                  |             +                |
          |                  |     BA for Confirmation      |
          |                  |----------------------------->|
          |                  |                              |



        The AN MAY send an Advertisement in an Access-Request message.
        If the HSN receives an invalid Advertisement, then the HSN MUST
        silently discard the Access-Request.

        A HSN MAY send the Selection after receiving a valid
        Advertisement.  It MAY also send the Selection in the absence
        of an Advertisement, based on local policies such as the AN
        clientÆs subscription profile.  When the AN receives an invalid
        Selection, it MUST treat the Access-Accept message as an Access
        Reject.

        If the AN receives a valid Selection in response to an Access-
        Request that did not contain an Advertisement, then the AN MAY
        honor the Selection.

        If the AN receives a valid Selection in response to an Access-
        Request that contained a valid Advertisement, then the AN MUST
        honor the Selection.

        In the absence of a Selection after sending a valid
        Advertisement, in accordance with local policy, the AN MAY


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        enforce its default bandwidth rate values or it MAY use ôbest
        effortö bandwidth for that client connection.

   2.2.2 Dynamic Bandwidth Allocation

        Dynamic bandwidth allocation uses the Change of Authorization
        (COA) message as defined in [3].  In accordance with [3] there
        are two methods for dynamically changing authorization
        attributes of a session.  These two methods are described in
        this section.

        At anytime during the session the HSN may send the AN a COA
        message containing session identification attributes (see [3]
        for the possible options).  The COA message may include
        authorization attributes in which case it is pushing the BAs to
        the AN; or it may instruct the AN to generate an Authorize-Only
        Access-Request (Access-Request with Service-Type set to
        ôAuthorize-Onlyö) in which case it is instructing the AN to
        pull the BAs.

        In either push or pull method, upon successful acceptance of
        the new bandwidth parameters for the session.  The AN MUST
        generate an Accouting-Stop record that contains the old
        bandwidth attributes followed by an Accounting-Start message
        that contains the new bandwidth attributes.

        In order to allow for downstream correlation of the accounting
        records, an AN that supports dynamic bandwidth allocation MUST
        include Acct-Multi-Session-Id when writing accounting records.


   2.2.2.1 Push Method

          In the Push Method, to effect a dynamic bandwidth change the
          HSN sends a COA message and includes a valid Selection.  The
          AN MAY also include other attributes in the COA message.
















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             AN                                            HSN
             |                                              |
             |                                              |
             |  COA + BAs for Selection                     |
             |<---------------------------------------------|
             |                                              |
             |                                              |
             |  COA ACK                                     |
             |--------------------------------------------->|
             |                                              |
             |                                              |
             | Accounting-Stop + old BAs for Confirmation   |
             |--------------------------------------------->|
             |                                              |
             | Accounting-Start + new bandwidth             |
             |--------------------------------------------->|
             |                                              |
             |                                              |


          Upon the successful reception of the COA message (see [3] for
          details) by the AN, if the COA message contains an invalid
          Selection, the AN MUST respond with a COA NAK with Error
          Cause (101) set to ôInvalid Requestö (404).

          If the AN is able to offer the requested bandwidth to the
          specified session, the AN MUST reply with a COA-ACK and it
          MUST generate an Accounting-Stop record containing the old
          bandwidth attributes followed by an Accounting-Start record
          containing the new bandwidth attributes.  If the AN can not
          comply with the request for new bandwidth it MUST reply with
          a COA-NAK with Error Cause (101) set to ô"Resources
          Unavailable"(506).

   2.2.2.2 Pull Method

          Alternatively, in the pull method, to effect a dynamic
          bandwidth change, as per [3], the HSN sends a COA message to
          instruct the AN to generate an Authorize-Only request
          (Access-Request with Service-Type set to Authorize-Only).












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            AN                                             HSN
             |                                               |
             |  COA  + Service-Type ôAuthorize Onlyö         |
             |<----------------------------------------------|
             |                                               |
             |  COA NAK + Service-Type ôAuthorize Onlyö      |
             |          + Error-Cause  "Request Initiated"   |
             |---------------------------------------------->|
             |                                               |
             | Access-Request + Service-Type ôAuthorize Onlyö|
             |                + BAs for Advertisement        |
             |---------------------------------------------->|
             |                                               |
             | Access-Accept + BAs for Selection             |
             |<----------------------------------------------|
             |                                               |
             | Accounting-Stop + old BAs for Confirmation    |
             |---------------------------------------------->|
             |                                               |
             | Accounting-Start + new BAs for Confirmation   |
             |---------------------------------------------->|
             |                                               |
             |                                               |


          As with the static bandwidth allocation (described earlier),
          the AN MAY Advertise the currently available bandwidth in the
          Authorize-Only message.

          Upon receiving the Authorize-Only message from the AN, the
          HSN MUST respond with either an Access-Accept message or an
          Access-Reject message.

          When responding with an Access-Accept message, the HSN MAY
          include the BAs for Selection.  If the Authorize-Only message
          included an Advertisement, the bandwidth parameters in
          Selection MUST be within the bounds of bandwidth parameters
          in the Advertisement received in the Authorize-Only message.

          Upon sending an Authorize-Only message, the AN will receive
          an Access-Accept message or an Access-Reject message.

          Upon receiving an Access-Reject in response to the Authorize-
          Only, the AN will terminate the session and send an
          Accounting-Stop record.

          Upon receiving an Access-Accept in response to an Authorize-
          Only request that does not contain bandwidth Selection, the
          AN MUST resume utilizing the existing bandwidth parameters,
          and it MUST NOT generate an Accounting Stop message.


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          Upon receiving an Access-Accept packet that contains an
          invalid Bandwidth Selection, the AN MUST treat the response
          as an Access-Reject and immediately terminate the session.

          Upon receiving an Access-Accept message in response to an
          Authorize-Only message that contained the Bandwidth
          Advertisement, then providing the bandwidth selections are
          within the bounds of the Advertisement, then AN MUST honor
          the requested bandwidth and generate an Accounting-Stop
          message that contains the old bandwidth attributes followed
          by an Account-Start message that contains the new bandwidth
          attributes.  If the bandwidth Selection were outside the
          bounds of the Advertisement, then the AN MUST treat the
          Access-Accept as an Access-Reject and immediately terminate
          the session.

          Upon receiving an Access-Accept message that contains a valid
          Selection in response to an Authorize-Only that did not
          contain the Advertisement, the AN MAY honor the Selection or
          it MAY continue to honor the previously agreed to bandwidth.
          In the former case, the AN must generate an Accounting Stop
          message containing the old bandwidth attributes followed by
          an Accounting-Start message containing the current bandwidth
          attributes.


   3. Operations

     Operation  is  identical  to  that  defined  in  RADIUS  AAA
     specifications  [1][2]  and  Dynamic  Authorization  Extensions  to
     Remote Authentication Dial In User Service (RADIUS)[3].

   4. Attribute Format/Syntax

     This section describes format and syntax for the attribute that
     carries AN bandwidth rate parameters. The attribute is used for
     bandwidth rate parameters Advertisement, Selection, and
     Confirmation.

     The attribute MAY be present in Access-Request, Access-Accept,
     Accounting-Request.











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     A summary of the AN Bandwidth Parameter Attribute is shown below.



       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Type      |    Length     |     Params                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                               Value                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


        Type

          TBD Network Bandwidth Capability


        Length

           8

        Params

           It indicates what the value signifies.  The values defined
           in the document are:

           1 û Average Minimum Bandwidth Rate for Ingress Traffic in
           bits per second
           2 û Average Minimum Bandwidth Rate for Ingress Traffic in
           Kilo bits per second
           3 û Average Minimum Bandwidth Rate for Ingress Traffic in
           Giga bits per second
           4 û Average Maximum Bandwidth Rate for Ingress Traffic in
           bits per second
           5 û Average Maximum Bandwidth Rate for Ingress Traffic in
           Kilo bits per second
           6 û Average Maximum Bandwidth Rate for Ingress Traffic in
           Giga bits per second
           7 û Average Minimum Bandwidth Rate for Egress Traffic in
           bits per second
           8 û Average Minimum Bandwidth Rate for Egress Traffic in
           Kilo bits per second
           9 û Average Minimum Bandwidth Rate for Egress Traffic in
           Giga bits per second
           10 û Average Maximum Bandwidth Rate for Egress Traffic in
           bits per second
           11 û Average Maximum Bandwidth Rate for Egress Traffic in
           Kilo bits per second
           12 û Average Maximum Bandwidth Rate for Egress Traffic in
           Giga bits per second


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        Value

           An integer value interpreted based the value of Param.

   5.  Table of Attribute(s)

     The following table provides a guide to which attribute(s) may be
     found in which kinds of packets, and in what quantity.


     Request Accept Reject Challenge Accounting  #  Attribute
                                      Request
       0-4      0-4      0      0         0-4   TBD  Network Bandwidth
                                                     Capability



   For Change-of-Authorization Messages

      Request   ACK      NAK   #   Attribute

       0-4      0-4      0    TBD   Network Bandwidth Capability


   6. Attribute Usage Examples

     This section provides an example on how Bandwidth attribute can be
     used to indicate the four bandwidth rate parameters, in
     Advertisement, Selection, and Confirmation.

     Ingress Minimum Bandwidth Rate for 28 Kilo bits per second

       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     TBD       |    7          |  2                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         28                                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Ingress Maximum Bandwidth Rate for 28 Kilo bits per second

       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     TBD       |    7          |  5                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         28                                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Egress Minimum Bandwidth Rate for 28 Kilo bits per second

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       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     TBD       |    7          |  8                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         28                                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Egress Maximum Bandwidth Rate for 28 Kilo bits per second

       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     TBD       |    7          |  11                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         28                                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



   7. IANA Considerations

     This  document  requires  the  assignment  of  three  new  RADIUS
     attribute numbers for the following attribute(s):

           AN-Bandwidth-Rate-Paramters

     See section 3 for the registered list of numbers.


   8. Security Considerations

     The attributes in this document have no additional security
     considerations beyond those already identified in [?].


   9. Acknowledgements

     The authors would like to thank Bernard Aboba (of Microsoft),
     Parviz Yegani (of Cisco), for their feedback and guidance.

   10. References

     [1] Rigney, C., Rubens, A., Simpson, W. and S. Willens, "Remote
         Authentication Dial In User Server (RADIUS)", RFC 2865, June
         2000.

     [2] Rigney, C., "RADIUS Accounting", RFC 2866, June 2000.

     [3] Chiba, M., Dommety, G., Eklud, M., Mitton, D., Aboba, B.,
         ôDynamic Authorization Extensions to Remote Authentication
         Dial In User Service (RADIUS)ö, RFC 3576, July 2003.

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   AuthorsÆ Addresses

   Farid Adrangi, Intel Corporatation        farid.adrangi@intel.com
   Chuck Black, Hewlett Packard Company      chuck.black@hp.com
   Paul Congdon, Hewlett Packard Company     paul.congdon@hp.com
   Farooq Bari, AT&T Wireless                farooq.bari@attws.com
   Avi Lior, Bridgwater Systems Corporation  avi@bridgewatersystems.com



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