Tsunemasa Hayashi, NTT
     Internet Draft                                 Haixiang He, Nortel
     Document:draft-ietf-mboned-maccnt-req-07.txt    Hiroaki Satou, NTT
     Intended Status: Informational                   Hiroshi Ohta, NTT
     Expires: December 22, 2008 July 16, 2009              Susheela Vaidya, Cisco Systems

                                                          June 20, 2008

                                                       January 12, 2009

         Requirements for Multicast AAA coordinated between Content
       Provider(s) and Network Service Provider(s) <draft-ietf-mboned-

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     This memo presents requirements in the area of accounting and
     access control for IP multicasting.  The scope of the
     requirements is limited to cases that Authentication,
     Accounting and Authorization (AAA) functions are coordinated
     between Content Provider(s) and Network Service Provider(s).
     General requirements for accounting and admission control
     capabilities including quality-of-service (QoS) related issues
     are listed.  This memo assumes that these capabilities can be
     realized by functions implemented at edges of a network based
     on IGMP or MLD.  Finally, cases for Content Delivery Services
     (CDS) are described as application examples which could benefit
     from multicasting accounting and access control capabilities as
     described in this memo.

     This memo defines requirements related to AAA issues for multi-
     entity provider models in which the network service provider and
     content provider cooperate to provide CDS and various related AAA
     functions for purposes such as protecting and accounting for the
     access to content and network resources.  The requirements are
     generally not relevant to cases in which there is not a reason to
     share AAA functions between separate entities.

                              Table of Contents

     Copyright Notice.................................................1

     1. Introduction..................................................3
     2. Definitions and Abbreviations.................................5
     2.1 Definitions..................................................5
     2.2 Abbreviations................................................6
     3. Problem Statement.............................................6
     3.1  Accounting Issues...........................................6
     3.2  Relationship with Secure Multicasting (MSEC)................8
     3.3  Regarding Access Media and User Separation..................8
     4. General AAA-related Functional Requirements for IP Multicasting
     5. Application Example and its Specific Requirements............14
     5.1 IP Multicast-based Content Delivery Service (CDS): CP and NSP
     are different entities (companies)..............................14
     5.1.1 Network Model for Multicast Content Delivery Service......15
     5.1.2 Content Delivery Service Requirements.....................17 Accounting Requirements.................................17 Authorization Requirements..............................18 Authentication Requirements.............................19
     5.2 IP Multicast-based Content Delivery Service (CDS): CP and NSP
     are the same entities (companies)...............................19
     6. Acknowledgments..............................................21
     7. IANA Considerations..........................................21
     8. Security Considerations......................................21
     9. Privacy considerations.......................................21
     10. Conclusion..................................................21
     Normative References............................................22
     Authors' Addresses..............................................23
     Full Copyright Statement........................................24
     Intellectual Property...........................................24

  1. Introduction

     This memo presents general functional requirements related to
     accounting, access control and admission control issues in IP
     multicasting networks. A multicast network which fulfills all of
     these requirements is called a "fully AAA and QoS enabled" IP
     multicasting network here. Fulfillment of all or some of the
     requirements will make possible more robust management of IP
     multicasting networks.

     IP multicasting is becoming widely used as a method to save
     network resources such as bandwidth or CPU processing power of the
     sender's server for cases where a large volume of information
     needs to be distributed to a very large number of receivers at a
     given data speed.  This trend can be observed both in enterprise
     use and in broadband services provided by network operator/service

     Distance learning within a university and in-house (in-company)
     sharing of multimedia information are examples of enterprise use.
     In these examples, sources generate high-bit rate (e.g., 6Mbit/s)
     streaming information.  When the number of receivers becomes large,
     such systems do not scale well without multicasting.

     On the other hand, a content delivery service (CDS) is an example
     of a broadband service provided by network operators/service
     providers.  Distribution of movies and other video programs to
     each user is a typical service.  Each channel requires large
     bandwidth (e.g., 6Mbit/s) and operator/service providers need to
     provide many channels to make their service attractive.  In
     addition, the number of receivers is large (e.g., more than a few
     thousands).  A system to provide this service does not scale well
     without multicasting.

     As such, multicasting can be useful to make a network more
     scalable when a large volume of information needs to be
     distributed to a large number of receivers.  However, multicasting
     according to current standards (e.g., IGMPv3[1] and MLDv2[2]) has
     drawbacks compared to unicasting when one applies it to commercial
     services.  Accounting of each user's actions is not possible with
     multicasting as it is with unicasting.  Accounting consists of
     grasping each user's behavior, when she/he starts/stops to receive
     a channel, which channel she/he receives, etc.

     There are limitations to the application of multicasting in usage
     models where user-based accounting is necessary, such as is the
     case with many commercial applications. These limitations have
     prevented the widespread deployment of multicasting.  Development
     and use of proprietary solutions to address such issues is an
     alternative to providing standardized solutions.  However, non-
     standard solutions have drawbacks in terms of interoperability or
     cost of development and maintenance.

     Without accounting capability in multicasting, information
     providers desiring accounting capability are forced to use
     unicasting even when multicasting would otherwise be desirable
     from a bandwidth/server resource perspective.  If multicasting
     could be used with user-based accounting capabilities, its
     applicability would be greatly widened.

     This memo first describes problems on accounting issues in
     multicasting.  Then the general requirements for this capability
     including QoS related issues are listed.  Finally, application
     examples which could benefit from multicasting with accounting
     capabilities are shown.

  2. Definitions and Abbreviations

  2.1 Definitions

     Authentication: action for identifying a user as a genuine one.

     Authorization: action for giving permission for a user to access
     content or the network.

     Eligible user: Users may be eligible (permitted) to access
     resources because of the attributes they have (e.g., delivery may
     require possession of the correct password or digital
     certificate), their equipment has (e.g., content may only be
     eligible to players that can decode H.264 or 3GPP streams), their
     access network has (e.g., HDTV content may only be eligible to
     users with 10 Mbps or faster access line), or because of where
     they are in network topology (e.g., HDTV content may not be
     eligible for users across congested links) or in actual geography
     (e.g., content may only be licensed for distribution to certain
     countries), and, of course, a mix of attributes may be required
     for eligibility or ineligibility.

     User: In this document user refers to a requester and a recipient
     of multicast data, termed a viewer in CDS.

     User-based accounting: actions for grasping each user's behavior,
     when she/he starts/stops to receive a channel, which channel
     she/he receives, etc.

  2.2 Abbreviations

     AAA: Authentication, Accounting and Authorization

     ASM: Any-Source Multicast

     CDS: Content Delivery Service

     CP: Content Provider

     IGMP: Internet Group Management Protocol

     MLD: Multicast Listener Discovery

     NSP: Network Service Provider

     SSM: Source Specific Multicast

     QoS: Quality of Service

  3. Problem Statement

  3.1  Accounting Issues

     In unicast communications, the server (information source) can
     identify the client (information receiver) and only permits
     connection by an eligible client when this type of access control
     is necessary.  In addition, when necessary, the server can grasp
     what the client is doing (e.g., connecting to the server, starting
     reception, what information the client is receiving, terminating
     reception, disconnecting from the server).

     On the other hand, in multicast communication with current
     standards (e.g., IGMPv3[1] or MLDv2[2]) the server just feeds its
     information to the multicast router [as in Fig.1].  Then, the
     multicast router replicates the data to any link which has at
     least one client requesting the information.    In this process,
     no eligibility check is conducted.  Any client can receive
     information just by requesting it.

     It is envisioned that there are many large-scale content
     distribution applications transferred over IP-based networks that
     can leverage multicasting technologies to meet their scalability
     requirements for clients and data volume, and that some of these
     applications require user-based accounting capabilities similar to
     available with unicast networks. For example, accounting is needed
     if one wants to charge for distributed information on a non-flat-
     fee basis. The current standards do not provide multicasting with
     authorization or access control capabilities sufficient to meet
     the requirements of accounting.

     |--- user ----|------------NSP------------------|-----CP---|

       | user   |\
       +--------+ \
                   \+------+    +------+    +------+    +------+
       +--------+   |Multi-|    |Multi-|    |Multi-|    |      |
       | user   |---|cast  |----|cast  |----|cast  |----|Server|
       +--------+   |router|    |router|    |router|    |      |
                   /+------+    +------+    +------+    +------+
       +--------+ /
       | user   |/

              Fig.1 Example network for multicast communication

     As such, the same level of user-based accounting capabilities as
     provided in unicast networks should be provided in multicast

  3.2  Relationship with Secure Multicasting (MSEC)

     In many cases, content encryption (e.g. MSEC) is an effective
     method for preventing unauthorized access to original content (in
     other words, the ability to decode data to return it to its
     generally usable form.)  This memo presents requirements for
     multicasting networks in the areas of 1) access control to prevent
     unauthorized usage of network resources (link bandwidth, router's
     processing power, etc.) , and 2) accounting to grasp user activity
     in a NSP.  The functional requirements do not require content
     encryption although it might solve some of the content related
     problems.  At this point, it is not yet clear whether encryption
     would be part of a solution and if so, what other components (if
     any) would also be required. Multicast streams generally consume
     large amounts of bandwidth for extended periods of time.
     Additionally, some multicast streams may have high-priority
     depending on a NSP's policy. NSP does not want to let ineligible
     users waste large amounts of bandwidth:  for example encryption
     protects against content viewing but NSP desires protection
     against DoS attacks of ineligible users wasting network resources,
     even if it is encrypted. Content encryption and multicast access
     control should both be able to coexist for more robust security.

  3.3  Regarding Access Media and User Separation

     The requirements defined in this memo apply to solutions that
     provide user separation either through physical separation
     provided by dedicated access media between the user and multicast
     router  (see  Fig.  1) or else through logical separation in cases
     of shared physical access media (e.g. using VLAN). However, IP
     multicast solutions with shared Layer 2 access media between the
     user and multicast router and no logical user separation (e.g.
     Ethernet with shared links and no VLAN) are out of scope of this
     memo. Nevertheless, some of the requirements in this memo defined
     for multicasting may also be relevant to multicasting over links
     without either physical or logical user separation.  Therefore in
     the interest of modularity and flexibility, solutions addressing
     the requirements of this memo may also take into account
     application to multicasting without such user separation.

  4. General AAA-related Functional Requirements for IP Multicasting

     In consideration of the issues presented in section 3, the
     following requirements have been derived:

     (1) User identification

     The network should be able to identify each user when they attempt
     to access the service so that necessary access controlling actions
     can be applied.  Also, it is necessary to identify the user's
     receiver (e.g. IP address) of each request (e.g., join/leave) for
     per host tracking purposes.

     With current protocols (IGMP/MLD), the sender cannot distinguish
     which receivers (end hosts) are actually receiving the information.
     The sender must rely on the information from the multicasting
     routers. This can be complicated if the sender and routers are
     maintained by different entities.

     (2) Issue of Network Resource Protection

     In order to guarantee certain QoS it is important for network
     providers to be able to protect their network resources from being
     wasted, (either maliciously or accidentally).

     For comparisons sake, for unicast this issue can be resolved e.g.
     by using RSVP in some cases.

     (2.1) Access control

     The network should be able to apply necessary access controlling
     actions when an eligible user requests an action (such as a join
     or a leave.)  The network should be able to reject any action
     requested from an ineligible user.

     (2.2) Control mechanism to support bandwidth of multicast stream
          from a physical port of edge router or switch
     The network may need to control the combined bandwidth for all
     channels at the physical port of the edge router or switch so that
     these given physical entities are not overflowed with traffic.

     (2.3) Control mechanism of number of channels delivered from a
          physical port of edge router and switch

     If an NSP desires to guarantee a certain level of QoS to CP and
     the receivers, it is necessary that the NSP be able to control the
     number of channels delivered from a physical port of an edge
     router and a switch in cases that there is a limit to the number
     of packet copies and/or number of channels that can be handled by
     multicast routers.

     For comparisons sake, for unicast this issue can be resolved e.g.
     by using RSVP in some cases.

     (3) User Authentication

     The network should be able to authenticate a user.

     (4) User Authorization

     The network, at its option, should be able to authorize a user's
     access to content or a multicast group, so as to meet any demands
     by a CP to prevent content access by ineligible users.  In the
     case that the NSP may wish to provide a service based on
     guaranteed delivery, the NSP would not want to waste its network
     resources on ineligible users.

     (5) Accounting and Billing

     In many commercial multicast situations, NSPs would like to be
     able to precisely grasp network resource consumption and CPs would
     like to be able to precisely grasp the content consumption by
     users.  Such information might be used for identifying highly
     viewed content for advertising revenue, ratings calculations,
     programming decisions, etc., as well as billing and auditing
     purposes. Also content and network providers may wish to provide
     users with access to their usage history.

     To assemble such an understanding of user behavior, it is
     necessary to precisely log information such as who (host/user) is
     accessing what content at what time (join action) until what time
     (leave action).  The result of the access-control decision (e.g.
     results of authorization) would also be valuable information.  The
     desired degree of logging precisions would depend on the
     application used.

     (5.1) How to share user information

     For commercial multicast applications it is important for NSP and
     CP to be able to share information regarding user's behaviour (as
     described in (5) in standardized ways.

     (6) Notification to Users of the Result of the Join Request

     It should be possible to provide information to the user about the
     status of his/her join request(granted/denied/other).

     (7) Service and Terminal Portability

     Depending on the service, networks should allow for a user to
     receive a service from different places and/or with a different
     terminal device.

     (8) Support of ASM and SSM

     Both ASM (G), and SSM (S,G) should be supported as multicast

     (9) Admission Control for Join Action
     In order to maintain a predefined QoS level, depending on the
     NSP's policy, a user edge should be able to control the number of
     streams it serves to a user, and total bandwidth consumed to that
     user. For example if the number of streams being served to a
     certain user has reached the limit defined by the NSP's policy,
     then the user edge should not accept a subsequent "join" until one
     of the existing streams is terminated.  Similarly, if the NSP is
     controlling by per-user bandwidth consumption, then a subsequent
     "join" should not be accepted if delivery of the requested stream
     would push the consumed bandwidth over the NSP policy-defined

     (10)  Channel Join Latency and Leave Latency

     Commercial implementations of IP multicasting are likely to have
     strict requirements in terms of user experience.  Join latency is
     the time between when a user sends a "join" request and when the
     requested data streaming first reaches the user.  Leave latency is
     the time between when a user sends a "leave" signal and when the
     network stops streaming to the user.

     Leave and Join latencies impact the acceptable user experience for
     fast channel surfing. In an IP-TV application, users are not going
     to be receptive to a slow response time when changing channels.
     If there are policies for controlling the number of simultaneous
     streams a user may access then channel surfing will be determined
     by the join and leave latencies.

     Furthermore, leave affects resource consumption:  with a low
     "leave latency" network providers could minimize streaming content
     when there are no audiences.

     It is important that any overhead for authentication,
     authorization, and access-control be minimized at the times of
     joining and leaving multicast channels so as to achieve join and
     leave latencies acceptable in terms of user experience. For
     example this is important in an IP-TV application, because users
     are not going to be receptive to a slow response time when
     changing channels.

     (11)  Scalability

     Solutions that are used for AAA and QoS enabled  IP multicasting
     should scale enough to support the needs of content providers and
     network operators. NSP's multicast access and QoS policies should
     be manageable for large scale users. (e.g. millions of users,
     thousands of edge-routers)

     (12) Small Impact on the Existing Products

     Impact on the existing products (e.g., protocols, software, etc.)
     should be as minimal as possible.

     Ideally the NSP should be able to use the same infrastructure
     (such as access control) to support commercial multicast services
     for the so called "triple play" services: voice (VoIP), video, and
     broadband Internet access services.

     When a CP requires the NSP to provide a level of QoS surpassing
     "best effort" delivery or to provide special services (e.g., to
     limited users with specific attributes), certain parameters of the
     CDS may be defined by a contractual relation between the NSP and
     the CP.  However, just as for best-effort unicast, multicast
     allows for content sourced by CPs without a contractual relation
     with the NSP.  Therefore, solutions addressing the requirements
     defined in this memo should not make obsolete multicasting that
     does not include AAA features. NSPs may offer tiered services,
     with higher QOS, accounting, authentication, etc., depending on
     contractual relation with the CPs. It is therefore important that
     Multicast AAA and QoS functions be as modular and flexible as

     (13) Deployable as Alternative to Unicast

     IP Multicasting would ideally be available as an alternative to IP
     unicasting when the "on-demand" nature of unicasting is not
     required. Therefore interfaces to multicasting should allow for
     easy integration into CDS systems that support unicasting.

     Especially equivalent interfaces for authorization, access control
     and accounting capabilities should be provided.

     (14) Multicast Replication

     The above requirements should also apply if multicast replication
     is being done on an access-node (e.g. DSLAMs or OLTs).

     Specific functional requirements for each application can be
     derived from the above general requirements.  An example is shown
     in the section 5.

  5. Application Example and its Specific Requirements

     This section shows an application example which could benefit from
     multicasting.  Then, specific functional requirements related to
     user-based accounting capabilities are derived.

  5.1 IP Multicast-based Content Delivery Service (CDS): CP and NSP are
     different entities (companies)

     Broadband access networks such as ADSL (Asymmetric Digital
     Subscriber Line) or FTTH (Fiber to the Home) have been deployed
     widely in recent years. Content Delivery Service (CDS) is expected
     to be a major application provided through broadband access
     networks. Because many services such as television broadcasting
     require huge bandwidth (e.g., 6Mbit/s) and processing power at
     content server, IP multicast is used as an efficient delivery
     mechanism for CDS.

     One way to provide high quality CDS is to use closed networks
     ("walled-garden" model).

     This subsection shows an example where CP and NSP are different
     entities (companies).

  5.1.1 Network Model for Multicast Content Delivery Service

     As shown in Fig.2, networks for CDS contain three different types
     of entities: Content Provider (CP), Network Service Provider (NSP),
     and user clients. An NSP owns the network resources
     (infrastructure). It accommodates content providers on one side
     and accommodates user clients on the other side. NSP provides the
     network for CDS to two other entities (i.e., CPs and user clients).
     A CP provides content to each user through the network of NSPs.
     NSPs are responsible for delivering the content to user clients,
     and for controlling the network resources.

       +-------------+  +-------------+  +-------------+
       | CP          |  | CP          |  | CP          |
       |          #1 |  |          #2 |  |          #3 |
       | +---------+ |  | +---------+ |  | +---------+ |
       | | content | |  | | content | |  | | content | |
       | | server  | |  | | server  | |  | | server  | |
       | +-------+-+ |  | +----+----+ |  | +-+-------+ |
       +----------\--+  +------|------+  +--/----------+
                   \           |           /
                    \          |          / <- network/network
                     \         |         /     interface
       +------------- \ ------ | ------ / ----+
       |               \       |       /      |
       |   NSP         +-+-----+-----+-+      |
       |               | Provider Edge |      |
       |               +-------+-------+      |   +-----------------+
       |                       |              |---| Information     |
       |                       |              |   | server          |
       |             +--+------+---+          |   +-----------------+
       |             | User Edge   |          |
       |             +--+---+---+--+          |
       |               /    |    \            |
       +------------- / --- | --- \ ----------+
                     /      |      \
                    /       |       \ <- user/network interface
                   /        |        \
        +---------++  +-----+----+   ++---------+
        |client #a |  |client #b |   |client #c |
        +----------+  +----------+   +----------+
        User A        User B         User C

                 Fig.2 Example of CDS network configuration

     The NSP provides the information server for all multicast channels,
     and a CP gives detailed channel information (e.g., Time table of
     each channel) to the information server. An end-user client gets
     the information from the information server. In this model,
     multicasting is used in the NSP's CDS network, and there are two
     different contracts. One is the contract between the NSP and the
     user which permits the user to access the basic network resources
     of the NSP.  Another contract is between the CP and user to permit
     the user to subscribe to multicast content. Because the CP and NSP
     are different entities, and the NSP generally does not allow a CP
     to control (operate) the network resources of the NSP, user
     authorization needs to be done by the CP and NSP independently.
     Since there is no direct connection to the user/network interface,
     the CP cannot control the user/network interface. A user may want
     to move to another place, or may want to change her/his device
     (client) any time without interrupting her/his reception of
     services.  As such, IP Multicast network should support
     portability capabilities.

  5.1.2 Content Delivery Service Requirements

     Below are listed specific requirements to support common business
     cases/ contractual arrangements for the IP Multicast-based Content
     Delivery Service. Accounting Requirements

     An NSP may have different contractual agreements with various CPs
     or various legal obligations in different locations.  One possible
     business relationship between a CP and NSP is that of a revenue
     sharing which could be on a per content/usage-base.  A solution
     should support varied billing and charging methods to satisfy both
     common legal and business/financial requirements to deploy
     multicasting services:  this requires accurate and near real-time
     accounting information about the user clients' activity accessing
     the content services.
     The user accessing particular content is represented by the user's
     activities of joining or leaving the corresponding multicast
     group/channel (<(*,g)> or (s,g)). In multicast networks, only NSPs
     can collect joining or leaving activities in real-time through
     their user edges. The NSPs can transfer the accounting information
     to related CPs for them to generate user billing information.
     Existing standard AAA technology may be used to transfer the
     accounting information.

     To match the accounting information with a particular user, the
     user has to be authenticated. Usually the account information of a
     user for content access is maintained by the CP. A user may have
     different user accounts for different CPs.(e.g. user_a@cp#1 and
     user_b@cp#2) The account is usually in the format of (username,
     password) so an user can access the content services from anywhere.
     For example, an user can access the CP from different NSPs.(e.g. a
     fixed line NSP and a mobile NSP). It should be noted that the user
     account used for content access can be different from the one used
     for network access maintained by NSPs.

     The NSP-CP model represents a multi-domain AAA environment. There
     are plural cases of the model depending on the trust relationship
     between the NSP and CP, and additional service requirements such
     as a certain QoS level guarantee or service/terminal portability.

     A mechanism is necessary to allow a CP and NSP to grasp each
     user's behavior independently.

     Another requirement related to accounting is the ability to notify
     a user when accounting really starts.  When a "free preview"
     capability is supported, accounting may not start at the same time
     as the user's joining of the stream.

     Any solution addressing the requirements of this memo should
     consider the Interdomain accounting issues presented in RFC-2975
     [3].  It is especially important to consider that the CP and NSP
     as separate administrative entities can not be assumed to trust
     one another.  The solution should be robust enough to handle
     packet loss between entity domains and assure for data integrity.
     In addition any solution should take into consideration common
     legal or financial requirements requiring confidential archiving
     of usage data. Authorization Requirements

    The NSPs are responsible for delivering content and are generally
    required to meet certain QoS levels or SLA (service level
    agreements). For example, video quality is very sensitive to packet
    loss. So if an NSP --due to limited network resources -- cannot
    meet quality requirements if it accepts an additional user request,
    the NSP should reject that user's access request to avoid charging
    the existing (i.e., already-joined) user for bad services.  For
    example, if an access line is shared by several users, an
    additional user's join may cause performance degradation for other
    users.  If the incoming user is the first user on a user edge, this
    will initiate the transmission of data between the provider edge
    and the user edge and this extra network traffic may cause
    performance degradation.  There may also be policies that do not
    necessarily give highest priority to the "first-come" users, and
    these should also be considered.

    In order to protect network resources against misuse/malicious
    access and maintain a QoS level, appropriate admission control
    function for traffic policing purposes is necessary so that the NSP
    can accept or reject the request without degrading the QoS beyond
    the specified level. Authentication Requirements

     There are two different aims of authentication.  One is
     authentication for network access, and another one is for content
     access. For the first case of authentication, NSP has a AAA server,
     and for the second case, each CP has a AAA server. In some cases,
     CPs delegate (outsource) the operation of user authentication to

     As such, in addition to network access, multicast access by a user
     also needs to be authenticated.  Content authentication should
     support the models where:
          - authentication for multicast content is outsourced to the
          - authentication for multicast content access is operated by
            the CP

  5.2 IP Multicast-based Content Delivery Service (CDS): CP and NSP are
     the same entities (companies)

     Another application example is the case where the content provider
     (CP) and network service provider (NSP) are the same entity
     (company) as shown in Fig. 3.  In the case that the CP and NSP are
     the same entity, some of the requirements indicated in 4.1 are not

     This model does not require the following items:

          - Communication method between sender (content server) and
            user.  Since they belong to the same company, they can use
            all the available information.

          - Methods to share user-related information between NSPs and
       |              +---------+                            |
       |              | content |                            |
       |              | server  |                            |
       |              +----+----+                            |
       |                   |                                 |
       | CP+NSP    +-------+-------+                         |
       |           | Provider Edge |                         |
       |           +-------+-------+  +--------------------+ |
       |                   |          | Information server | |
       |                   |          +--------------------+ |
       |           +-------------+                           |
       |           | User Edge   |                           |
       |           +--+---+---+--+                           |
       |             /    |    \                             |
       +----------- / --- | --- \ ---------------------------+
                   /      |      \
                  /       |       \ <- user/network interface
                 /        |        \
      +---------++  +-----+----+   ++---------+
      |Client #a |  |client #b |   |client #c |
      +----------+  +----------+   +----------+
        User A    User B     User C

                 Fig.3 Example of CDS network configuration
  6. Acknowledgments

     The authors of this draft would like to express their appreciation
     to Pekka Savola of Netcore Ltd., Daniel Alvarez, and Toerless
     Eckert of Cisco Systems, Sam Sambasivan of AT&T, Sanjay Wadhwa of
     Juniper, Tom Anschutz and Steven Wright of BellSouth, Nicolai
     Leymann of T-Systems, Carlos Garcia Braschi of Telefonica Empresas,
     Marshall Eubanks of Multicast Techno, Stephen Rife of NTT and
     David Meyer in his role as mboned WG chair, as well as their
     thanks to the participants of the MBONED WG in general.

     Funding for the RFC Editor function is currently provided by the
     Internet Society.

  7. IANA Considerations

     This memo does not raise any IANA consideration issues.

  8. Security Considerations

     Accounting capabilities can be used to enhance the security of
     multicast networks by excluding ineligible clients from the

     These requirements are not meant to address encryption issues.
     Any solution meeting these requirements should allow for the
     implementation of encryption such as MSEC on the multicast data.

  9. Privacy considerations

     Any solution which meets these requirements should weigh the
     benefits of user-based accounting with the privacy considerations
     of the user. For example solutions are encouraged when applicable
     to consider encryption of the content data between the content
     provider and the user in such a way that the Network Provider does
     not know the contents of the channel.

  10. Conclusion
     This memo describes general requirements for providing AAA and QoS
     enabled IP multicasting services. It lists issues related to
     accounting, authentication, authorization and admission control
     for multicast content delivery.  Content Delivery Services with
     different business models are cited as the type of application
     which could benefit from the capabilities of AAA and QoS enabled
     IP multicasting described in this document.

  Normative References

     [1] B. Cain, et. al., "Internet Group Management Protocol, Version
         3", RFC3376, October 2002.

     [2] R. Vida, et. al., "Multicast Listener Discovery Version 2
         (MLDv2) for IPv6", RFC3810, June 2004.

     [3] Aboba B , et. al., "Introduction to Accounting Management",
         RFC 2975, October 2000.

  Authors' Addresses

             Tsunemasa Hayashi
             NTT Network Innovation Laboratories
             1-1 Hikarino'oka, Yokosuka-shi, Kanagawa, 239-0847 Japan
             Phone: +81 46 859 8790
             Email: hayashi.tsunemasa@lab.ntt.co.jp

             Haixiang He
             600 Technology Park Drive Billerica, MA 01801, USA
             Phone: +1 978 288 7482
             Email: haixiang@nortel.com

             Hiroaki Satou
             NTT Network Service Systems Laboratories
             3-9-11 Midoricho, Musashino-shi, Tokyo, 180-8585 Japan
             Phone: +81 422 59 4683
             Email: satou.hiroaki@lab.ntt.co.jp

             Hiroshi Ohta
             NTT Network Service Systems Laboratories
             3-9-11 Midoricho, Musashino-shi, Tokyo, 180-8585 Japan
                     Phone: +81 422 59 3617
             Email: ohta.hiroshi@lab.ntt.co.jp

             Susheela Vaidya
             Cisco Systems, Inc.
             170 W. Tasman Drive San Jose, CA 95134
             Phone: +1 408 525 1952
             Email: svaidya@cisco.com
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