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Internet Draft AAA Framework for Multicasting June 2006
Hiroaki Satou, NTT
Internet Draft Hiroshi Ohta, NTT
Expires: December 25, 2006 Tsunemasa Hayashi, NTT
Haixiang He, Nortel Networks
June 23, 2006
AAA Framework for Multicasting
<draft-ietf-mboned-multiaaa-framework-01.txt>
Status of this Memo
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Satou, Ohta, Hayashi, He [Page 1]
Internet Draft AAA Framework for Multicasting June 2006
This Internet-Draft will expire on December 25, 2006.
Copyright Notice
Copyright (C) The Internet Society (2006)
Abstract
This memo provides a generalized framework for solution standards to
meet the requirements presented in draft-ietf-mboned-maccnt-req-
04.txt, "Requirements for Accounting, Authentication and
Authorization in Well Managed IP Multicasting Services". In this
framework a user sends a request for multicast data to a network
service provider. The network service provider selects the
appropriate content provider to send the user's request. The request
is sent by the network service provider to the content provider
transparently in a way so that the network service provider and
content provider do not need to know the corresponding user id for
the same user in the other provider's domain. The content provider
then responds with an indication of "success" or "failure" to the
network provider and in the case of "success", the network provider
may delivery the requested data to the user. The network service may
base its decision to deliver such data to the user based on its
bandwidth management policy. The framework is designed to be
flexible and extendible, so it will be possible to implement
partially enabled versions as well as fully enabled versions of the
model. Also an additional entity may provide transit of requests
between network service providers and content providers, either
through relaying or tunneling.
1. Introduction
1.1 Purpose and Background
IP multicasting is designed to serve cases where a single source of
data content is to be concurrently streamed to multiple recipients.
In these types of cases, multicasting provides resource efficiencies
Satou, Ohta, Hayashi, He [Page 2]
Internet Draft AAA Framework for Multicasting June 2006
(both for the overall network and the content server) relative to
unicasting. These efficiencies are possible because of the avoidance
of unnecessary duplication of streams, video/audio processing, etc.
Multicasting also provides resource efficiencies relative to IP
broadcasting in that content data is only delivered to end hosts
which request it.
There are many real-life situations where IP multicasting is selected
as the technology used for concurrent content delivery of identical
content data to multiple end-hosts. "Requirements for Accounting,
Authentication and Authorization in Well Managed IP Multicasting
Services", (draft-ietf-mboned-maccnt-req-04.txt, hereafter MACCNT-
REQ-draft) describes the requirements in CDN services using IP
multicast[1]. "Issues Related to Receiver Access Control in the
Current Multicast Protocols" (draft-ietf-mboned-rac-issues-03.txt,
hereafter RAC-ISSUES-draft) discusses the requirements and existing
support for large-scale, multi-entity content delivery services[2].
The requirements are derived from:
- need for user tracking and billing capabilities
- need for network access control and/or content access control
to satisfy the requirements of the CP
- methods for sharing information between the network service
provider and content provider to make it possible to fulfill the
above two requirements.
Detailed requirements are presented in MACCNT-REQ-draft. These
requirements include mechanisms for recording end-user requests and
provider responses for content-delivery, sharing user information
(possibly anonymously depending on the trust model) between content
provider and network service provider, and protecting resources
through the prevention of network and content access by unauthorized
users, as well as other AAA related requirements.
The purpose of this memo is to provide a generalized framework for
solution standards to meet these requirements. This framework is to
provide a basis for defining protocols, but definition of the actual
protocols is outside of the scope of this memo.
2. Definitions and Abbreviations
2.1 Definitions
For the purposes of this memo the following definitions apply:
Accounting: actions for grasping each user's behavior, when she/he
starts/stops to receive a channel, which channel she/he receives,
etc.
Authentication: action for identifying a user as a genuine one.
Satou, Ohta, Hayashi, He [Page 3]
Internet Draft AAA Framework for Multicasting June 2006
Authorization: action for giving permission to access the content or
network to a user.
Receiver: an end-host or end-client which receives content. A
receiver may be distinguishable by a network ID such as MAC address
or IP address.
User: a human with a user account. A user may possibly use multiple
reception devices. Multiple users may use the same reception device.
Note: The definition of a receiver (device) and a user (human) should
not be confused.
2.2 Abbreviations
For the purposes of this draft the following abbreviations apply:
ACL: Access Control List
CDN: Content Delivery Network
CDS: Content Delivery Services
CP: Content Provider
NSP: Network Service Provider
TP: Transit Provider
Satou, Ohta, Hayashi, He [Page 4]
3. Framework and Roles of Entities
3.1 Framework for multicast AAA allowing bandwidth Management
A general high-level framework can be represented as follows.
+------------------------------+
| user |
| |
+------------------------------+
| Access ^ Response
| Request | & Multicast Data
V |
+------------------------------+
| NSP |
| |
+------------------------------+
| Access ^ Response
| Request | (Success)
v |
+------------------------------+
| CP |
| |
+------------------------------+
For the sake of simplicity, the above diagram portrays a case where
there is a single NSP entity and a single CP entity. Under the
framework it is possible for there to be multiple CPs connected to
the same NSP. It is also possible for the same CP to be connected to
multiple NSP networks (e.g. network selection). In other words the
relationship of NSP:CP can be described as 1:1, 1:N or M:N.
Furthermore it is possible that the NSP and CP could be the same
entity.
Description of Roles:
The user selects a CP and a NSP when the user requests content. The
NSP may be automatically selected by a user terminal: e.g. a fixed
line NSP for STB or a mobile NSP for mobile phone.
The CP is responsible for Authentication and Authorization of users'
access to content that the CP manages. The CP hopes to collect
accounting information related to the access of their content. The CP
may choose to authenticate and authorize NSPs which are eligible to
provide users access to its contents. When the CP cannot or decides
not to provide content to be multicast to users, the CP is
responsible for notifying the NSP of the reason.
The NSP is responsible for managing its network resources. The NSP
may perform admission control to protect bandwidth resource and needs
Hayashi, He, Satou, Ohta [Page 5]
Internet Draft AAA Framework for Multicasting June 2006
authorized information regarding user access for bandwidth
management.
It is also responsible for confirming (authentication by proxy) with
the CP whether the user is eligible to receive content. When the NSP
cannot or decides not to multicast to users, the NSP is responsible
for notifying the users of the reason.
In addition to the three basic entities of user, NSP and CP, this AAA
framework for multicasting supports transit provision which transfers
multicast streams from the CP to the NSP.
3.2 Multiple User IDs
Users may be assigned separate user IDs for each subscription for
various NSPs and CPs. When the user wants to access content or
otherwise use the network, the user registers the corresponding user
ID with a request for content, etc: web authentication is one
possible method.
Terminal portability can be realized if the NSP authenticates a user
using a user ID. This allows the user to access the content from
various network access points.
Each CP may identify users by the user IDs it has issued to them.
The NSP and CP do not need to know the corresponding user id for the
same user in the other provider's domain, and it is not necessary
that there is a one to one relationship. It is quite possible for
one person to hold multiple user ids for the same provider.
3.3 Accounting
The NSP should not manage multicast states on a subnet basis, but on
a user basis because the NSP needs to notify start and stop times for
accounting purposes. This means that the NSP sends an indication for
Join and Leave on a user basis.
The NSP should log both user and host information for each join and
leave, indicating the corresponding multicast source for each action.
It is important that such log use a standard format so that it can be
shared with the CP. Intermittent logs between the join and leave
also could serve useful in billing discrepancies, and disconnects
without leaves. Ideally a solution would also provide standard ways
for the NSP to share logged information with the CP. When shared it
is important that the CP be able to match the user to the user within
its domain.
3.4 Access Control and CP selection by NSP
When a NSP receives an access request from a user, it is necessary
for the NSP to determine to which CP the request is directed. It is
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Internet Draft AAA Framework for Multicasting June 2006
necessary for the NSP to ensure that it is not spoofed by an
inappropriate CP.
3.5 Network Resource Management by NSP
After authorizing a user request, the NSP may conduct admission
control based on its bandwidth management policy. For example, if the
NSP manages the shared bandwidth of access lines, the NSP might
calculate available bandwidth and necessary bandwidth, and based on
these calculations determine to accept or reject a user request.
3.6 Access Control and Distinguishing of Users by CP
The user ID and authentication information are forwarded
transparently by the NSP so that the CP can distinguish the user, as
well as authenticate and authorize the request.
3.7 Caching of AAA results
An NSP should be able to cache AAA results based an understanding
between the NSP and a CP. The AAA cache would store information
about permissions of a specific user to receive multicast data from
specified channel(s) up to specified expiration date(s) and time(s).
If such caching is implemented, a method must exist for the CP to
communicate this permission information to the NSP. The NSP refers
to the AAA cache and if the cache indicates that the user has
permission to receive multicast data from a specific channel at that
time, the NSP may forward the data without querying the CP.
It should be possible for a CP to send a directive to the NSP to
refresh or change permissions for a user for specific channel(s).
It is necessary for the NSP to requery the CP for authorization
should a user be receiving content when the permission expires.
It would be desirable to have a mechanism by which CPs could
proactively push permission information to the cache even when not
specifically queried by the NSP.
4. Network Connection Model and Functional Components
Section 3.1 introduces the high-level AAA framework for multicasting.
This section provides more detail on the network connection model and
constituent functional components.
4.1 Basic Connection Model
Satou, Ohta, Hayashi, He [Page 7]
Internet Draft AAA Framework for Multicasting June 2006
+-------------+
| user |
| |
+-------------+
^ Access & Resource
| Request
v
+-------------+
| NSP |
| |
+-------------+
^ Access
| Request
v
+-------------+
| CP |
| |
+-------------+
First a user desiring authorization sends an Access request to an NSP
which then forwards it on to the appropriate CP for Authentication
and Authorization. The CP responds with either "success" or
"failure". If "success", the NSP may forward a success response
and stream multicast data to the user.
In this model the user selects the NSP to which to send its content
request. Based on this request the NSP selects an appropriate CP to
which it forwards the request. The CP responds to the NSP's request:
it may not respond to another NSP in regards to the request.
In this model, as described in section 3.1, the relationship between
NSP and CP can be 1:1, 1:N or M:N. Users may connect to multiple
networks, and networks have multiple users.
Satou, Ohta, Hayashi, He [Page 8]
Internet Draft AAA Framework for Multicasting June 2006
4.2 Transit Provision
The diagram below shows that a Transit Provider(hereafter, TP) may
relay requests between NSPs and CPs.
+-------------+
| user |
| |
+-------------+
^ Access & Resource
| Request
v
+-------------+
| NSP |
| |
+-------------+
^ Access & Resource
| Request
v
+-------------+
| TP |
| |
+-------------+
^ Access
| Request
v
+-------------+
| CP |
| |
+-------------+
For the sake of simplification the above diagram shows a 1-1
relationship between an NSP and a TP. However it is also possible
for a single NSP to connect to multiple TPs, and a single TP to
multiple NSPs.
A single TP may connect to one or more CPs. Similarly just as a
single CP may connect to multiple NSPs (as described in the general
high-level framework, section 3.1), a single CP may connect to one or
more TPs.
A solution will include a mechanism through which the NSPs know which
TP(s) are to be used to communicate with which CP(s), and CPs know
which TP(s) to use for which NSP(s). When a TP receives an access or
resource request from an NSP or CP, it must relay the request to the
correct CP or NSP, respectively. Minimally, this means that it must
reconstruct the request with translated address information. In this
model therefore a TP must understand the format and meaning of the
requests.
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Internet Draft AAA Framework for Multicasting June 2006
There may be multiple TPs between a NSP and CP so that a TP is
actually receiving from and/or sending requests to another TP and not
directly from/to a NSP or CP.
4.3 Transit with Tunnels
In addition to the above model of request relaying, a TP may
communicate requests through tunneling based on the contract between
the TP and the NSP and/or between the TP and the CP. So in this case
the TP will not directly need to process the contents of the access
and resource request (such as, header information), but instead pass
the request directly to the correct NSP or CP, using a separate
protocol to wrap the original requests.
Below is a diagram, representing how a TP can provider tunneling
between NSP(s) and CP(s).
+-----------------+
| user |
| |
+-----------------+
^ Access & Resource
| Request
v
+------------------+
| NSP |
| |
+------------------+
|^|
|:|
|:|
+-|:|--------------+
| |:| TP |
| |:| |
+-|:|--------------+
|:|
|:| Tunnel
|:|
|V|
+------------------+
| CP |
| |
+------------------+
In this model too, the relationship between NSP and TP and between
transit provider and CP can be 1:1, 1:N or M:N.
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Internet Draft AAA Framework for Multicasting June 2006
4.4 Constituent Logical Functional Components of the fully enabled AAA
Framework
Section 3.1 introduces the high-level AAA framework for multicasting.
Below is a diagram of a fully enabled multicasting network with AAA,
including the logical components within the various entities.
+-------------------------------+
| user |
| |
+-------------------------------+
^
| Access & resource request
v
+-------------------------------+
| NSP |
| |
|+--------------+ +---------+|
||NR Management |<-->|AAA Proxy|| (NR= network resource)
|+--------------+ RR +---------+| (RR= resource request)
+-------------------------------+
^
| Access request
v
+------------------------------+
| CP |
| |
| +---------+ |
| | AAA | |
| +---------+ |
+------------------------------+
In the fully enabled model the NSP provides proxying of
authentication and authorization between the NSP and CP, as well as
user-based accounting. The AAA proxy server of the NSP communicates
with the CP's AAA server. Although not show in the above diagram for
the sake of simplicity, in addition to direct proxying between a NSP
and CP, this proxying may be done through a TP. This means that the
transit provider too is able to support AAA proxying.
In the fully enabled model the NSP also includes a component that
provides network resource management (e.g. QoS management), as
described in section 3.4, "Network Resource Management by NSP". When
a transit provider is used it may also provide Network Resource
management of its own resources.
4.5 Modularity of the framework
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Internet Draft AAA Framework for Multicasting June 2006
In the interest of flexibility, this framework is modular so that it
is possible that partially enabled versions of the models are
supported. A AAA-enabled version provides AAA functionality without
Network Resource management. A Network-Resource-Management-enabled
(QoS-enabled) version provides Network Resource management without
AAA functionality. Similarly, the possibility of one or more layers
of transit provision between an NSP and CP is in the interest of
modularity and extendibility.
5. IANA considerations
This memo does not raise any IANA consideration issues.
6. Security considerations
Refer to section 3.3. Also the user information related to
authentication with the CP should be protected in some way.
Otherwise, this memo does not raise any new security issues which are
not already existing in the original protocols. Enhancement of
multicast access control capabilities may enhance security
performance.
7. Conclusion
This memo provides a generalized framework for solution standards to
meet the requirements presented in MACCNT-REQ-draft. Further work
should be done to break down the content provider and network service
provider entities into their functional objects such as edge devices,
AAA servers, etc.
Normative References
[1] Hayashi, et. al., "Accounting, Authentication and Authorization
Issues in Well Managed IP Multicasting Services", draft-ietf-
mboned-maccnt-req-04.txt, February 2006, Work in Progress.
[2] Hayashi, et. al., "Issues Related to Receiver Access Control in
the Current Multicast Protocols", draft-ietf-mboned-rac-issues-
03.txt, April 2006, Work in Progress.
Authors' Addresses
Hiroaki Satou
NTT Network Service Systems Laboratories
3-9-11 Midoricho, Musashino-shi, Tokyo, 180-8585 Japan
Phone : +81 422 59 4683
Satou, Ohta, Hayashi, He [Page 12]
Internet Draft AAA Framework for Multicasting June 2006
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
Tsunemasa Hayashi
NTT Network Innovation Laboratories
1-1 Hikari-no-oka, Yokosuka-shi, Kanagawa, 239-0847 Japan
Phone: +81 46 859 8790
Email: tsunemasa@gmail.com
Haixiang He
Nortel
600 Technology Park Drive
Billerica, MA 01801, USA
Phone: +1 978 288 7482
Email: haixiang@nortel.com
Comments
Comments are solicited and should be addressed to the mboned working
group's mailing list at mboned@lists.uoregon.edu_and/or the authors.
Satou, Ohta, Hayashi, He [Page 13]
Internet Draft AAA Framework for Multicasting June 2006
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This Internet-Draft will expire on December 25, 2006.
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Satou, Ohta, Hayashi, He [Page 14]
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