Tsunemasa Hayashi, NTT Internet Draft Haixiang He, Nortel Networks Document: draft-hayashi-maccnt-02.txt Hiroaki Satou, NTT Expires: August 21, 2005 Hiroshi Ohta, NTT Susheela Vaidya, Cisco Systems February 21, 2005 Accounting, Authentication and Authorization Issues in Well Managed IP Multicasting Services <draft-hayashi-maccnt-02.txt> Status of this Memo This document is an Internet-Draft and is subject to all provisions of section 3 of RFC 3667. By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she become aware will be disclosed, in accordance with RFC 3668. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on August 21, 2005 Copyright Notice Copyright (C) The Internet Society (2005) Abstract Hayashi, He, Satou, Ohta, Vaidya [Page 1]
Internet Draft draft-hayashi-maccnt-02 February, 2005 This Internet Draft (I-D) describes problems in the area of accounting and access control for multicasting. General requirements for accounting capabilities including quality-of-service (QoS) related issues are listed. This I-D assumes that these capabilities can be realized by functions implemented at edges of a network based on IGMP or MLD. Such functions would log in dedicated database information obtained from edge routers. 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 the I-D. It is proposed that this I-D be used as a starting point for further discussion on these issues. Table of contents Copyright Notice...................................................1 1. Introduction....................................................3 2. Definitions and Abbreviations...................................4 2.1 Definitions....................................................4 2.2 Abbreviations..................................................4 3. Problem statement...............................................5 3.1 Accounting issues.............................................5 3.2 Relationship with secure multicasting (MSEC)..................6 4. Functional general requirements for well managed IP multicasting6 5. Application example and its specific requirements...............8 5.1 IP Multicast-based Content Delivery Service (CDS): CP and NSP are different entities (companies).....................................8 5.1.1 Network model for Multicast Content Delivery Service.........9 5.1.2 Content Delivery Service Requirements.......................10 5.1.2.1 Accounting Requirements...................................10 5.1.2.2 Authorization Requirements................................11 5.1.2.3 Authentication Requirements...............................11 5.2 IP Multicast-based Content Delivery Service (CDS): CP and NSP are the same entities (companies).....................................12 6. IANA considerations............................................13 7. Security considerations........................................13 8. Conclusion.....................................................13 Normative References..............................................13 Full Copyright Statement..........................................15 Intellectual Property.............................................15 Acknowledgement...................................................15 Hayashi, He, Satou, Ohta, Vaidya [Page 2]
Internet Draft draft-hayashi-maccnt-02 February, 2005 1. Introduction The intention of this Internet Draft (I-D) is to initiate a discussion focused on accounting, authentication and authorization issues for well-managed IP multicasting services (ôwell-managedö defined at the end of this introduction). The I-D proposes for the identified requirements to be taken on as a working item within the mboned WG. This I-D also intends to develop an informational RFC on requirements for well managed IP multicasting. 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 large number of receivers. This trend can be observed both in enterprise use and in broadband services provided by network operator/service providers. 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 are typical services. 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). The system to provide this service does not scale well without multicasting. As such, multicasting can be useful to make the 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. IP multicasting can be used to distribute free material efficiently, but there are limitations to multicasting in usage models where usage accounting is necessary, such as many commercial applications. Although multicasting has already been used in several applications, in many cases it is used in such a way that accounting is not necessary. Alternatively, one could develop and use a proprietary Hayashi, He, Satou, Ohta, Vaidya [Page 3]
Internet Draft draft-hayashi-maccnt-02 February, 2005 solution to address this issue. 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 I-D first describes problems on accounting issues in multicasting. Then the general requirements for this capability including QoS related issues are listed. This I-D assumes that these capabilities can be realized by functions implemented at edges of a network based on IGMP or MLD. Such functions would record into dedicated database information obtained from edge routers. Finally, application examples which could benefit from multicasting with accounting capabilities are shown. It is proposed that this I-D be used as a starting point for a discussion on these issues. This I-D will present general functional requirements related to accounting, authentication and authorization issues in IP multicasting networks, and a multicast network which fulfills these requirements will be called a ôwell managedö IP multicasting network. 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. 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 ASM: Any-Source Multicast CDS: Content Delivery Service CP: Content Provider IGMP: Internet Group Management Protocol Hayashi, He, Satou, Ohta, Vaidya [Page 4]
Internet Draft draft-hayashi-maccnt-02 February, 2005 MLD: Multicast Listener Discovery NSP: Network Service Provider SSM: Single-Source 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 as in Fig.1, the server just feeds its information to the multicast router. Then, the multicast router replicates the information to distribute to the clients. According to current standards (e.g., IGMPv3[1] or MLDv2[2]), the multicast router feeds the replicated information to any link which has at least one client requesting the information. In this process, no eligibility check is conducted. Any client can receive the information just by requesting. In other words, the current standards do not provide multicasting with authorization or access control capabilities sufficient to meet the requirements of accounting. +--------+ | user |\ +--------+ \ \+------+ +------+ +------+ +------+ +--------+ |Multi-| |Multi-| |Multi-| | | | user |---|cast |----|cast |----|cast |----|Server| +--------+ |router| |router| |router| | | /+------+ +------+ +------+ +------+ +--------+ / | user |/ +--------+ Fig.1 Example network for multicast communication This is the major reason why multicasting is only used for cases where no user-based accounting capabilities are necessary. However, since more and more information is transferred over IP-based networks Hayashi, He, Satou, Ohta, Vaidya [Page 5]
Internet Draft draft-hayashi-maccnt-02 February, 2005 and some of these applications may require accounting capabilities, it is easy to envision the requirement of supporting such cases. For example, accounting is needed if one wants to charge for distributed information on a non-flat-fee basis. If the volume of information and number of clients are large, it is beneficial to use multicasting from the network resource efficiency point of view. As such, the same level of user-based accounting capabilities as provided in unicast networks should be provided in multicast networks. 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 useable form.) This I-D presents requirements for multicasting networks in the areas of 1) access control to prevent unauthorized access to the network, and 2) accounting to grasp user activity. It is not the intention of this I-D to propose alternatives to encryption. Access control, accounting and encryption are separate technologies. The implementation of any of these technologies does not preclude the use of the others. 4. Functional general requirements for well managed IP multicasting It seems beneficial to use IGMP or MLD for access controlling in multicast networks. However, from the considerations presented in section 3, there are issues in the following areas: (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 source (user) of each request (e.g., join/leave). (2) Access control The network should be able to apply necessary access controlling actions when an eligible user requests. The network should be able to reject any action requested from an ineligible user. (3) User authentication The network should be able to authenticate a user. Hayashi, He, Satou, Ohta, Vaidya [Page 6]
Internet Draft draft-hayashi-maccnt-02 February, 2005 (4) User authorization The network should be able to authorize a userÆs access to content or a multicast group, so as to meet any demands by a CP to prevent content access by ineligible users. Also, the NSP does not want to waste their network resources on ineligible users. Eligibility can be defined in several ways. The definition of an "eligible user" should be discussed further. (5) Accounting and billing Networks need to be able to grasp each user's behavior so that accounting and billing are possible. When the network is built based on IGMP, a user's behavior is represented by join/leave actions. As such, it is necessary to detect each user's join/leave actions precisely enough for the application used. Accounting and billing should be associated with these join/leave actions. Networks need database functions to realize user-based accounting through the accumulation of logs from edge routers. (6) Service and terminal portability Networks should allow for a user to receive a service from different places and/or with a different terminal device. (7) Support of ASM and SSM Both ASM (G), and SSM (S,G) should be supported as multicast models. (8) Admission control for join action In order to maintain a predefined QoS level, an edge router should not accept a consequent "join" after a "leave" until the termination of the stream of the multicast group which was "left". This is essential to protect against e.g., multicast denial of service (DoS) attacks. (9) Quick reaction When a user sends a request, it should be responded to as quickly as possible. For example, when a user changes the channel they are receiving, the reaction should be as quick as possible. Quick Hayashi, He, Satou, Ohta, Vaidya [Page 7]
Internet Draft draft-hayashi-maccnt-02 February, 2005 reactions are essential to provide attractive and easy-to-use services. (10) Scalability Solutions that are used for well managed IP multicasting should scale enough to support the needs of content providers and network operators. (11) Small impact on the existing products Impact on the existing products (e.g., protocols, software, etc.) should be as minimal as possible. (12) 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). Hayashi, He, Satou, Ohta, Vaidya [Page 8]
Internet Draft draft-hayashi-maccnt-02 February, 2005 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 end user clients. An NSP owns the network resources (infrastructure). It accommodates content providers on one side and accommodates end user clients on the other side. NSP provides the network for CDS to two other entities (i.e., CPs and end user clients). A CP provides content to each end-user client through the network of NSPs. NSPs are responsible for delivering the content to end 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 | +----------+ +----------+ +----------+ End user A End user B End 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 Hayashi, He, Satou, Ohta, Vaidya [Page 9]
Internet Draft draft-hayashi-maccnt-02 February, 2005 channel) to the information server. An end-user client gets the information from the information server. In this model, multicast is used in the NSP's CDS network, and there are two different contracts. One is the contract between the NSP and the end user which permits the user to access the basic network resources of the NSP. Another contract is between the CP and end user to permit the user to subscribe 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. An end user may want to move to another place, or may want to change her/his device (client) anytime without interrupting her/his receiving services. As such, IP Multicast network should support portability capabilities. 5.1.2 Content Delivery Service Requirements To have a successful business providing multicast, there are some specific requirements for the IP Multicast-based Content Delivery Service. 5.1.2.1 Accounting Requirements Since the CP and NSP are different business entities, they need to share the profit. Such a profit sharing business relationship requires accurate and near real-time accounting information about the end user clients' activity on accessing the content services. The accounting information should be per content/usage-base to enable varied billing and charging methods. The user accessing a 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 group joining or leaving activities through their last-hop multicast access edge devices in real-time. The NSPs can transfer the accounting information to related CPs for them to generate final end user billing information. The normal AAA technology can be used to transfer the accounting information. To match the accounting information with a particular end-user client, the end-user client has to be authenticated. Usually the account information of an end-user client for content access is maintained by the CP. An end user client may have different user accounts for different CPs. The account is usually in the format of (username, password) so an end user client can access the content services from anywhere. For example, an end user client can access the CP from different NSPs. It should be noted that the user account used for Hayashi, He, Satou, Ohta, Vaidya [Page 10]
Internet Draft draft-hayashi-maccnt-02 February, 2005 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 userÆs joining of the stream. 5.1.2.2 Authorization Requirements The NSPs are responsible for delivering content and are 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 cannot meet the quality requirements due to limited network resources if it accepts an additional user request, the NSP should reject that end 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 a performance degradation for other users. If the incoming user is the first user on an edge node, this will initiate the transmission of data between the multicast router and the edge node and this extra network traffic may cause performance degradation. There may also be policies that do not necessarily give highest priority to the ôfirst- comeö 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. 5.1.2.3 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 NSPs. Hayashi, He, Satou, Ohta, Vaidya [Page 11]
Internet Draft draft-hayashi-maccnt-02 February, 2005 As such, in addition to network access, multicast group access by a user also needs to be authenticated. Content authentication should support the models where: - authentication for multicast content is outsourced to the NSP. - authentication for multicast content access is operated by the content provider 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 required. This model does not require the following items: - Communication method between sender (server) and user (end host). Since they belong to the same company, they can use all the available information. - Methods to share user-related information between network providers and content providers. +-----------------------------------------------------+ | +---------+ | | | content | | | | server | | | +----+----+ | | | | | CP+NSP +-------+-------+ | | | Provider Edge | | | +-------+-------+ +--------------------+ | | | | Information server | | | | +--------------------+ | | +-------------+ | | | User Edge | | | +--+---+---+--+ | | / | \ | +----------- / --- | --- \ ---------------------------+ / | \ / | \ <- user/network interface / | \ +---------++ +-----+----+ ++---------+ |user #a | |user #b | |user #c | +----------+ +----------+ +----------+ End user A End user B End user C Fig.3 Example of CDS network configuration Hayashi, He, Satou, Ohta, Vaidya [Page 12]
Internet Draft draft-hayashi-maccnt-02 February, 2005 6. IANA considerations This I-D does not raise any IANA consideration issues. 7. Security considerations Accounting capabilities can be used to enhance the security of multicast networks by excluding ineligible clients from the networks. 8. Conclusion This I-D describes general requirements for providing "well managed" IP multicasting services. It lists issues related to accounting, authentication, authorization and admission control for multicast content delivery, with the goal of finding a solution implemented at edges of the network based on IGMP or MLD. This solution likely would assume the existence of a database in the network dedicated to accumulating logs obtained from edge routers. Content Delivery Services with different business models is cited as an application which could benefit from the capabilities of "well managed" IP multicasting described in this document. It is proposed that this document be used as a starting point for discussing requirements for "well managed" IP multicasting services. 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. Authors' Addresses Tsunemasa Hayashi NTT Network Innovation Laboratories 1-1 Hikari-no-oka, Yokosuka-shi, Kanagawa, 239-0847 Japan Phone: +81 46 859 8790 Email: hayashi.tsunemasa@lab.ntt.co.jp Haixiang He Nortel Networks 600 Technology Park Drive Billerica, MA 01801, USA Phone: +1 978 288 7482 Email: haixiang@nortelnetworks.com Hayashi, He, Satou, Ohta, Vaidya [Page 13]
Internet Draft draft-hayashi-maccnt-02 February, 2005 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 Hayashi, He, Satou, Ohta, Vaidya [Page 14]
Internet Draft draft-hayashi-maccnt-02 February, 2005 Full Copyright Statement Copyright (C) The Internet Society (2004). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the IETF's procedures with respect to rights in IETF Documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf ipr@ietf.org. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Hayashi, He, Satou, Ohta, Vaidya [Page 15]