INTERNET DRAFT Henrik Basilier Category: Informational Ericsson, Inc. Title: draft-calhoun-sip-aaa-reqs-00.txt Pat R. Calhoun Date: July 2000 Sun Microsystems, Inc. Matt Holdrege ipVerse Tony Johansson Ericsson, Inc. James Kempf Sun Microsystems, Inc. AAA Requirements for IP Telephony/Multimedia 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 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 document is an individual contribution for consideration by the SIP Working Group of the Internet Engineering Task Force. Comments should be submitted to the diameter@diameter.org mailing list. Distribution of this memo is unlimited. Copyright (C) The Internet Society 2000. All Rights Reserved. Calhoun et al. expires January 2001 [Page 1] INTERNET DRAFT July 2000 Abstract The AAA Working Group has been defining requirements for Network Access in an Inter-Domain (roaming) network, both Mobile IP and NASREQ. Some of these requirements were input from work done in the 3rd Generation wireless SDOs. These same SDO's have a need to tie their IP Intelligent Servers (e.g. Softswitches, Call Agents, SIP Servers, etc.) to their AAA infrastructure. This specification defines some requirements for both the AAA and IP Telephony protocols (SIP, MEGACO, etc.) This first Internet Draft is intended to simulate discussions within the SIP Working Group, in order to come up with a set of requirements that could then be used to begin protocol design. Table of Contents 1.0 Introduction 1.1 Requirements language 2.0 Network Architecture 3.0 Requirements 4.0 Security Considerations 5.0 References 6.0 Acknowledgements 7.0 Authors' Addresses 8.0 Full Copyright Statement Calhoun et al. expires January 2001 [Page 2] INTERNET DRAFT July 2000 1.0 Introduction The AAA Working Group has been defining requirements [2] for Network Access in an Inter-Domain (roaming) network, both Mobile IP and NASREQ. Some of these requirements were input from work done in the 3rd Generation wireless SDOs. These same SDO's have a need to tie their IP Intelligent Servers (e.g. Softswitches, Call Agents, SIP Servers, etc.) to their AAA infrastructure. This specification defines some requirements for both the AAA and IP Telephony protocols (SIP, MEGACO, etc.) This first Internet Draft is intended to simulate discussions within the SIP Working Group, in order to come up with a set of requirements that could then be used to begin protocol design. 1.1 Requirements language In this document, the key words "MAY", "MUST, "MUST NOT", "optional", "recommended", "SHOULD", and "SHOULD NOT", are to be interpreted as described in [13]. 2.0 Network Architecture In this specification, we assume that a roaming SIP user is a superset of a user in its home network, therefore we will concentrate on the former. Figure one (1) provides an example of an inter-domain SIP network. This architecture was chosen, due to its similarities to the existing AAA architecture for Mobile IP [4] and NASREQ [5]. Although a driving force towards the integration of SIP and AAA is the next generation wireless networks (3G), it is desirable that the architecture proposed be similar, if not identical, to the wireline architecture. In the example provided in Figure 1, a user (bob@xyz.com) gets access to the visited network. The method by which access to the network is gained is completely outside the scope of this document, but it is assumed that the AAA infrastructure was used to authenticate and authorized the user's request to access the network. Once the user has access to the network, he discovers the local SIP Proxy, which could be done using a service discovery protocol, such as SLP [6]. When the SIP client issues its SIP Register message to the local proxy, an AAA message is created, which includes the SIP message as Calhoun et al. expires January 2001 [Page 3] INTERNET DRAFT July 2000 opaque data, to the local AAA server, known as the AAAF. The AAAF MAY apply local policy decisions to the request, which may cause the request to be denied. If the request is not denied, it is forwarded to the user's Home AAA Server (AAAH), using the domain portion of the user's NAI [7]. The AAAH server is responsible for authenticating the SIP message, ensuring that the correct secret information shared with the SIP Client, or user, was used to generate the authentication information. Further, it authorizes the client's registration request based on its local policy, which could include validating that the user is permitted to receive service in a visited network. At the time of authorization, the AAAH MAY assign a Home SIP Server, which MAY be done for load balancing reasons. It would also record the user's current binding information. In the event that a dynamic security association is to be setup between the SIP Proxy and the Home SIP server, the AAAH MAY generate keying information, similar to those described in [4]. The AAAH then returns a reply, back to the AAAF, and SIP Proxy, which includes profile information, known as authorization information. This information could include Quality of Service information, that the visited network would apply to the user's SIP session (and related RTP flows). The SIP Registration message is then forwarded to the Home SIP Server. In the event that the AAAH server had returned dynamic security association information, the SIP Proxy would add authentication information, generated using the key received by the AAAH. When the SIP Client wishes to initiate a call, the invite message is forwarded to the SIP Proxy. In the event that the AAAH server returned dynamic security association information, the mobile would have included the authentication information, generated using the session keys generated on the AAAH. If the Home SIP Server is to be contacted for all calls generated by the SIP Client, the SIP Proxy authenticates the message to it. The Home SIP Server (or SIP Proxy if the Home is not involved) initiates an authorization request to the AAA infrastructure. The AAAH should determine whether the requested call is permitted, and may perform additional policy verifications, and return the appropriate response. If a successful response was returned by the AAAH, the Home SIP Server forwards the SIP invite to the proper destination. When the SIP session (and RTP flow) is established, the SIP servers initiate accounting records, which are transfered to the AAA infrastructure. The accounting records should include usage Calhoun et al. expires January 2001 [Page 4] INTERNET DRAFT July 2000 information, that is necessary for billing purposes. The traditional telco world current makes use, and prefers, non-cumulative accounting information, therefore any interim accounting information MUST be non-cumulative. At the end of the SIP session, a final accounting record should be issued that includes a summary of the session. Visited Network Home Network +--------+ +--------+ +--------+ |abc.com | | Broker | |xyz.com | | AAAF |<----->| AAA |<-------->| AAAH | +->| server | | Server | | server | | +--------+ +--------+ +--------+ | ^ ^ | AAA | | AAA | | | v v v +-----------+ +-----------+ +-----------+ |Softswitch/| |Softswitch/| |Softswitch/| | SIP | | SIP |<--------------->| Home SIP | | Proxy | | Proxy | SIP | Server | +-----------+ +-----------+ +-----------+ ^ | SIP | v +---------+ | SIP | | Client | bob@xyz.com +---------+ Figure 1: Inter-Domain SIP Architecture 3.0 Requirements From the previous section, we can extract the following requirements: - A basic requirement for Service Providers is to integrate different networks for more efficient operations. IETF AAA efforts support this idea by striving for a single AAA architecture and protocol set. Whether access is supported by PPP, Mobile-IP, MEGACO or SIP, a common architecture and protocol set SHOULD be used. - the AAA infrastructure MUST support for AAA brokers and proxies. - The AAA infrastructure MUST support SIP users roaming to a Calhoun et al. expires January 2001 [Page 5] INTERNET DRAFT July 2000 foreign (or visited) networks. - It is assumed that a hybrid/distributed model is used, where the actual session/call control is allowed in either the home or visited network. The AAAH makes this decision at the time the user is initially authorized. - The AAA infrastructure MUST be able to perform policy control of the SIP servers/proxies, controlling their behavior/functionality based on user and/or network policies. - Certain localized services (e.g. 911) must be provided by the serving network. - The AAAH will authenticate, and authorize, a user and the session being requested. The Home AAA server may implement whatever policy it wishes on authorizing the call, such as time of day, long distance, etc. - The AAA infrastructure MUST be able to distribute (push or pull) subscriber/service profiles to the relevant SIP servers, based on policies. - Support for the AAA infrastructure to return Quality of Service (QOS) properties to the visited network, to be applied to the user's telephony session. - The AAA infrastructure MUST be able to do an allocation of a SIP server for a subscriber at registration time, based on policies, load distribution etc. - Dynamic security associations created between the visited SIP Server and the Home SIP Server. This will be necessary for basic SIP proxy authentication. The AAAH MAY provide the dynamic security association to the Proxy and Home SIP Servers. - Allow SIP messages to be sent through the AAA infrastructure as opaque data, to allow the Home AAA server to authenticate the message. This eliminates the need for the Home AAA server to send the user's "password" to SIP servers. - The AAA infrastructure MUST support SIM and smart cards. - Ability for SIP Servers to provide the duration of a call, the parties involved, and other relevant information to the visited and home AAA servers as accounting information. - Tthe AAA protocol MUST support for both cumulative, and non- cumulative, accounting models. - Support for pre-paid calls - The AAA accounting messages MUST Separate the "air time" information from those generated via additional services (e.g. 3-way calling, etc.) - Support for real-time and non-real time accounting data transfers. - The protocol MUST be able to provide the user with real-time feedback on the cost of the call. 4.0 Security Considerations Calhoun et al. expires January 2001 [Page 6] INTERNET DRAFT July 2000 It is assumed that integrating AAA and IP Telephony will not introduce any new security risks. Therefore, the AAA data MUST be secured and obscured when transiting the network, the endpoints MUST be authenticated before data is sent, and the endpoints MAY be authorized to access certain types of AAA data. 5.0 References [1] M. Handley, H. Schulzrinne, E. Schooler, J. Rosenberg, "SIP: Session Initiation Protocol". RFC 2543, March 1999. [2] Aboba et al, "Network Access AAA Evaluation Criteria", IETF work in progress, draft-ietf-aaa-na-reqts-02.txt, March 2000. [3] S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [4] S. Glass, S. Jacobs, C. Perkins, "Mobile IP Authentication, Authorization, and Accounting Requirements", draft-ietf- mobileip-aaa-reqs-03.txt, IETF work in progress, March 2000. [5] M. Beadles, D. Mitton, "Criteria for Evaluating Network Access Server Protocols", draft-ietf-nasreq-criteria-05.txt, IETF work in progress, June 2000. [6] E. Guttman, C. Perkins, J. Veizades, M. Day. "Service Location Protocol, Version 2", RFC 2165, June 1999. [7] Aboba, Beadles "The Network Access Identifier." RFC 2486. Janu- ary 1999. [8] H. Schulzrinne, L. Slutsman, I. Faynberg, H. Lu, "Interworking between SIP and INAP". draft-schulzrinne-sin-00.txt, IETF Work in Progress, July 2000. 6.0 Acknowledgements Many of the requirements, and thoughts expressed in this Internet Draft, came from presentations that were presented at various 3rd Generation wireless meetings, such as 3GPP, 3GPP2 and MWIF. 7.0 Authors' Addresses Questions about this memo can be directed to: Calhoun et al. expires January 2001 [Page 7] INTERNET DRAFT July 2000 Henrik Basilier Ericsson Inc. 2100 Shattuck Ave. Berkeley, Califonia, 94704 USA Phone: +1 858-361-4314 Fax: +1 510-666-3999 E-mail: henrik.basilier@ericsson.com Pat R. Calhoun Network and Security Research Center, Sun Laboratories Sun Microsystems, Inc. 15 Network Circle Menlo Park, California, 94025 USA Phone: +1 650-786-7733 Fax: +1 650-786-6445 E-mail: pcalhoun@eng.sun.com Matt Holdrege ipVerse 223 Ximeno Ave. Long Beach, CA 90803 U.S.A. E-mail: matt@ipverse.com Tony Johansson Ericsson Inc. 2100 Shattuck Ave. Berkeley, Califonia, 94704 USA Phone: +1 510-305-6108 Fax: +1 510-666-3999 E-mail: tony.johansson@ericsson.com James Kempf Network and Security Research Center, Sun Laboratories Sun Microsystems, Inc. 15 Network Circle Menlo Park, California, 94025 Calhoun et al. expires January 2001 [Page 8] INTERNET DRAFT July 2000 USA Phone: +1 650-786-5890 Fax: +1 650-786-6445 E-mail: james.kempf@eng.sun.com 8.0 Full Copyright Statement Copyright (C) The Internet Society (2000). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this docu- ment itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of develop- ing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The lim- ited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DIS- CLAIMS 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. Calhoun et al. expires January 2001 [Page 9]