AAA Working Group M. Garcia-Martin, Ed. Internet-Draft Nokia Expires: March 25, 2006 M. Belinchon M. Pallares-Lopez C. Canales Ericsson K. Tammi Nokia September 21, 2005 Diameter Session Initiation Protocol (SIP) Application draft-ietf-aaa-diameter-sip-app-08 Status of this Memo 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 becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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 March 25, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract This document specifies the Diameter Session Initiation Protocol (SIP) Application. This is a Diameter application that allows a Diameter client to request authentication and authorization Garcia-Martin, et al. Expires March 25, 2006 [Page 1] Internet-Draft Diameter SIP Application September 2005 information. This application is designed to be used in conjunction with the Session Initiation Protocol (SIP), and provides a Diameter client in a SIP server with the ability to request a Diameter server the authentication of users and authorization of SIP resources usage. Table of Contents 1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Applicability Statement . . . . . . . . . . . . . . . . . . . 7 5. Overview of Operation . . . . . . . . . . . . . . . . . . . . 7 5.1. General Architecture . . . . . . . . . . . . . . . . . . . 8 5.2. Modes of operation . . . . . . . . . . . . . . . . . . . . 9 5.3. Diameter Server Authenticates the User, nonce generated in the Diameter server . . . . . . . . . . . . . 9 5.4. Delegating Final Authentication Check to the SIP Server, nonce generated in the Diameter server . . . . . . 13 5.5. SIP Server Requests Authentication and Authorization, nonce generated in the Diameter server . . . . . . . . . . 16 5.6. SIP Server Requests Authentication and Authorization, nonce generated in the Diameter client . . . . . . . . . . 17 5.7. Locating the recipient of the SIP request . . . . . . . . 19 5.8. Update of the User Profile . . . . . . . . . . . . . . . . 19 5.9. SIP Soft State Termination . . . . . . . . . . . . . . . . 20 5.10. Diameter Server Discovery . . . . . . . . . . . . . . . . 21 6. Advertising Application Support . . . . . . . . . . . . . . . 23 7. Diameter SIP Application Command Codes . . . . . . . . . . . . 24 7.1. User-Authorization-Request (UAR) Command . . . . . . . . . 24 7.2. User-Authorization-Answer (UAA) Command . . . . . . . . . 25 7.3. Server-Assignment-Request (SAR) Command . . . . . . . . . 29 7.4. Server-Assignment-Answer (SAA) Command . . . . . . . . . . 31 7.5. Location-Info-Request (LIR) Command . . . . . . . . . . . 35 7.6. Location-Info-Answer (LIA) Command . . . . . . . . . . . . 36 7.7. Multimedia-Auth-Request (MAR) Command . . . . . . . . . . 37 7.8. Multimedia-Auth-Answer (MAA) Command . . . . . . . . . . . 39 7.9. Registration-Termination-Request (RTR) Command . . . . . . 42 7.10. Registration-Termination-Answer (RTA) Command . . . . . . 42 7.11. Push-Profile-Request (PPR) Command . . . . . . . . . . . . 44 7.12. Push-Profile-Answer (PPA) Command . . . . . . . . . . . . 46 8. Diameter SIP Application AVPs . . . . . . . . . . . . . . . . 47 8.1. SIP-Accounting-Information AVP . . . . . . . . . . . . . . 49 8.1.1. SIP-Accounting-Server-URI AVP . . . . . . . . . . . . 50 8.1.2. SIP-Credit-Control-Server-URI AVP . . . . . . . . . . 50 8.2. SIP-Server-URI AVP . . . . . . . . . . . . . . . . . . . . 50 8.3. SIP-Server-Capabilities AVP . . . . . . . . . . . . . . . 50 8.3.1. SIP-Mandatory-Capability AVP . . . . . . . . . . . . . 51 Garcia-Martin, et al. Expires March 25, 2006 [Page 2] Internet-Draft Diameter SIP Application September 2005 8.3.2. SIP-Optional-Capability AVP . . . . . . . . . . . . . 51 8.4. SIP-Server-Assignment-Type AVP . . . . . . . . . . . . . . 51 8.5. SIP-Auth-Data-Item AVP . . . . . . . . . . . . . . . . . . 52 8.5.1. SIP-Authentication-Scheme AVP . . . . . . . . . . . . 53 8.5.2. SIP-Item-Number AVP . . . . . . . . . . . . . . . . . 53 8.5.3. SIP-Authenticate AVP . . . . . . . . . . . . . . . . . 54 8.5.4. SIP-Authorization AVP . . . . . . . . . . . . . . . . 54 8.5.5. SIP-Authentication-Info AVP . . . . . . . . . . . . . 55 8.5.6. Digest AVPs . . . . . . . . . . . . . . . . . . . . . 56 8.6. SIP-Number-Auth-Items AVP . . . . . . . . . . . . . . . . 57 8.7. SIP-Deregistration-Reason AVP . . . . . . . . . . . . . . 58 8.7.1. SIP-Reason-Code AVP . . . . . . . . . . . . . . . . . 58 8.7.2. SIP-Reason-Info AVP . . . . . . . . . . . . . . . . . 58 8.8. SIP-AOR AVP . . . . . . . . . . . . . . . . . . . . . . . 58 8.9. SIP-Visited-Network-Id AVP . . . . . . . . . . . . . . . . 59 8.10. SIP-User-Authorization-Type AVP . . . . . . . . . . . . . 59 8.11. SIP-Supported-User-Data-Type AVP . . . . . . . . . . . . . 60 8.12. SIP-User-Data AVP . . . . . . . . . . . . . . . . . . . . 60 8.12.1. SIP-User-Data-Type AVP . . . . . . . . . . . . . . . . 60 8.12.2. SIP-User-Data-Contents AVP . . . . . . . . . . . . . . 61 8.13. SIP-User-Data-Already-Available AVP . . . . . . . . . . . 61 8.14. SIP-Method AVP . . . . . . . . . . . . . . . . . . . . . . 61 9. New Values for Existing AVPs . . . . . . . . . . . . . . . . . 62 9.1. Extension to the Result-Code AVP Values . . . . . . . . . 62 9.1.1. Success Result-Code AVP Values . . . . . . . . . . . . 62 9.1.2. Transient Failures Result-Code AVP Values . . . . . . 62 9.1.3. Permanent failures Result-Code AVP Values . . . . . . 63 10. Authentication Details . . . . . . . . . . . . . . . . . . . . 64 10.1. Generation of nonces . . . . . . . . . . . . . . . . . . . 65 11. Migration from RADIUS . . . . . . . . . . . . . . . . . . . . 66 11.1. Gateway from RADIUS Client to Diameter Server . . . . . . 66 11.2. Gateway from Diameter Client to RADIUS Server . . . . . . 67 11.3. Known Limitations . . . . . . . . . . . . . . . . . . . . 67 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 67 12.1. Application Identifier . . . . . . . . . . . . . . . . . . 68 12.2. Command Codes . . . . . . . . . . . . . . . . . . . . . . 68 12.3. AVP Codes . . . . . . . . . . . . . . . . . . . . . . . . 68 12.4. Additional Values for the Result-Code AVP Value . . . . . 68 13. Security Considerations . . . . . . . . . . . . . . . . . . . 69 14. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 69 15. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 69 16. Changes With Respect Previous Versions . . . . . . . . . . . . 70 16.1. Changes in draft-ietf-aaa-diameter-sip-app-08.txt from -08.txt . . . . . . . . . . . . . . . . . . . . . . . . . 70 16.2. Changes in draft-ietf-aaa-diameter-sip-app-07.txt from -06.txt . . . . . . . . . . . . . . . . . . . . . . . . . 70 16.3. Changes in draft-ietf-aaa-diameter-sip-app-06.txt from -05.txt . . . . . . . . . . . . . . . . . . . . . . . . . 71 Garcia-Martin, et al. Expires March 25, 2006 [Page 3] Internet-Draft Diameter SIP Application September 2005 16.4. Changes in draft-ietf-aaa-diameter-sip-app-05.txt from -04.txt . . . . . . . . . . . . . . . . . . . . . . . . . 71 16.5. Changes in draft-ietf-aaa-diameter-sip-app-04.txt from -03.txt . . . . . . . . . . . . . . . . . . . . . . . . . 72 16.6. Changes in draft-ietf-aaa-diameter-sip-app-03.txt from -02.txt . . . . . . . . . . . . . . . . . . . . . . . . . 73 16.7. Changes in draft-ietf-aaa-diameter-sip-app-02.txt from -01.txt . . . . . . . . . . . . . . . . . . . . . . . . . 73 16.8. Changes in draft-ietf-aaa-diameter-sip-app-01.txt from -00.txt . . . . . . . . . . . . . . . . . . . . . . . . . 73 16.9. Changes in draft-ietf-aaa-diameter-sip-app-00.txt from draft-belinchon-aaa-diameter-mm-app-01.txt . . . . . . . . 74 17. References . . . . . . . . . . . . . . . . . . . . . . . . . . 75 17.1. Normative References . . . . . . . . . . . . . . . . . . . 75 17.2. Informational References . . . . . . . . . . . . . . . . . 75 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 77 Intellectual Property and Copyright Statements . . . . . . . . . . 79 Garcia-Martin, et al. Expires March 25, 2006 [Page 4] Internet-Draft Diameter SIP Application September 2005 1. Terminology In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119 [RFC2119] and indicate requirement levels for compliant implementations. 2. Definitions For the purpose of this document, the following terms and definitions apply. o *Node: * an addressable device attached to a computer network that implements SIP functionality, Diameter functionality or a combination of both. For the purpose of this document, the following terms and definitions given in RFC 3261 [RFC3261] Section 6, apply: o *Address-of-Record (AOR)* o *Outbound proxy* o *Proxy* o *Server (SIP server)* o *User Agent (UA)* o *User Agent Client (UAC)* o *User Agent Server (UAS)* For the purpose of this document, the following terms and definitions given in RFC 3588 [RFC3588] Section 1.3, apply: o *Authorization* o *Authentication* o *AVP* o *Diameter Client* o *Diameter Server* o *Home Realm* o *Redirect Agent* o *User* 3. Introduction This document specifies the Diameter Session Initiation Protocol (SIP) Application. This is a Diameter application that allows a Diameter client to request authentication and authorization information to a Diameter server for Session Initiation Protocol Garcia-Martin, et al. Expires March 25, 2006 [Page 5] Internet-Draft Diameter SIP Application September 2005 (SIP) [RFC3261] based IP multimedia services. We assume that the SIP server and the Diameter client are located in the same node, so that the SIP server is able to receive and process SIP requests and responses which in turn relies on the AAA infrastructure for authenticating the SIP request and authorizing the usage of particular SIP services. This document provides Diameter procedures to implement certain required functionality when SIP is the protocol chosen to initiate and tear-down multimedia sessions or when SIP is used for other non- session related applications. However, this document does not mandate any particular mapping of SIP procedures to Diameter SIP application procedures, nor does it mandate any particular sequence of events between SIP and Diameter. This document provides useful examples to show the interaction between SIP and the Diameter SIP application in order to achieve the desired functionality. This application does not require or is not related to other authentication services provided by the Diameter Mobile IPv4 [RFC4004] or the Diameter Network Access Server [RFC4005] applications. This Diameter SIP application is loosely related to the Diameter Credit Control Application [RFC4006]. Although both applications are independent, the Diameter SIP application is able to supply the addresses of credit control servers that will be implementing the Diameter Credit Control Application [RFC4006]. Section 4 discusses assumptions and configurations assumed by this document. Section 5 provides the reader with informative descriptions of the Diameter SIP application commands and responses and some guidance to their linkage with SIP procedures. Advertising of this application is specified in Section 6. Section 7 provides a normative description of all the new Diameter commands defined by this specification. This application extends the Result-Code Attribute-Value-Pair (AVP) with some new values. Further information is described in Section 9. This application defines some new AVPs. All these AVPs are described in Section 8. Some extra information about authentication is provided in Section 10. Garcia-Martin, et al. Expires March 25, 2006 [Page 6] Internet-Draft Diameter SIP Application September 2005 4. Applicability Statement This document assumes a general architecture where a Home Realm is composed of one or more nodes implementing Diameter or SIP functions. Users are issuing SIP requests to access SIP resources. For each particular user, the Home Realm needs to authenticate and authorize the usage of those resources and/or route to the appropriate node. We assume that the database containing the user related data is located outside the SIP node that requires authorization. Data belonging to different users may be stored in different nodes in the Home Realm, but we assume that all the data related to a particular user is stored in a single node. Central to the architecture is the fact that the user data is stored in a single point in the network. This restriction does not mandate a particular implementation, e.g., it is possible to implement clusters of databases operating in mirror mode to provide redundancy. The property required by this specification is that the user data the Diameter Server has access to is stored safely in what, from the external point of view, is seen as a single user database. This document allows several configurations of the Home Realm. In one configuration, a SIP server is allocated to a user for the purpose of triggering and executing services. The allocation of the SIP server may be done dynamically, e.g., at the time the user registers in the network. This configuration requires a SIP server, typically located at the edge of the network, that is able to allocate another SIP server for the user and also supports routing of SIP requests and responses towards that allocated SIP server. Both SIP server nodes implement a Diameter Client. In another configuration, the address of a SIP outbound proxy is configured (by means outside the scope of this specification) into the SIP endpoint. The outbound Diameter Client in the SIP outbound proxy node authenticates the user, requests authorization for SIP requests and performs accounting activities. 5. Overview of Operation This section provides an informative description of how the Diameter SIP application can be used together with SIP. This section is not intended to mandate any specific usage of the Diameter SIP application nor does it mandate a specific mapping between SIP and Diameter messages. We provide a collection of examples that show how the required AAA functionality can be achieved in conjunction with SIP. Garcia-Martin, et al. Expires March 25, 2006 [Page 7] Internet-Draft Diameter SIP Application September 2005 5.1. General Architecture The Diameter SIP application can be used in a SIP environment where an interface to a AAA infrastructure is required to authenticate and authorize the usage of SIP resources. This application provides support for SIP User Agents and proxies that implement and use HTTP Digest Authentication [RFC2617], which is the authentication mechanism mandated by SIP [RFC3261]. The application is extensible and, if need arises, it can be extended to provide support for other authentication mechanisms. This application provides a limited support for accounting services, limited to the Diameter server being able to provide the addresses of accounting severs to the Diameter client. Figure 1 below shows a general overview of the integration of the SIP architecture with the AAA architecture. According to Figure 1, there is one or more SIP User Agents (UA) that initiate or terminate SIP traffic through one or more SIP servers. Both SIP servers implement a Diameter client that supports the Diameter application described in this specification. +--------+ UAR/UAA +--->|Diameter|<----+ PPR/PPA LIR/LIA | | server | | MAR/MAA | +--------+ | SAR/SAA | | RTR/RTA | | v v +------+ SIP +--------+ SIP +--------+ SIP +------+ | SIP |<--------->| SIP |<-------->| SIP |<--------->| SIP | | UA | |server 1| |server 2| | UA | +------+ +--------+ +--------+ +------+ ^ ^ UAR/UAA | | LIR/LIA | | MAR/MAA | +--------+ | SAR/SAA +--->|Diameter|<----+ | SL | +--------+ Figure 1: Architecture of the Diameter application for SIP In Figure 1, it can be seen that SIP server 1 sends different Diameter commands and receives different responses to those sent and received by SIP server 2. This is because SIP server 1 in Figure 1 is located at the edge of a network, and its main task is to locate SIP server 2. SIP server 2 is requesting and receiving Garcia-Martin, et al. Expires March 25, 2006 [Page 8] Internet-Draft Diameter SIP Application September 2005 authentication and authorization data from the Diameter server and is not located at the edge of the network. The Diameter Subscriber Locator (SL) serves for the purposes of locating the Diameter server that contains the user related data. Its functionality is based on the Diameter redirect mechanism, and is further described in Section 5.10. It should be noted that this document does not mandate any particular SIP/AAA architecture. However, the Diameter SIP application provides the functionality needed to accommodate all the different architectures where SIP and Diameter are used. The following subsections provide an informative overview of the Diameter SIP application, its commands, and a possible interaction with SIP signaling. 5.2. Modes of operation This Diameter application provides support for two modes of operation. These modes of operation are related to the generation of nonces in HTTP Digest authentication. HTTP Digest requires the authenticating server to generate a nonce. In the case of the Diameter SIP application, the nonce can be generated either in the Diameter client (SIP server) or in the Diameter server. A mixture of nonce generation is not supported. Whenever a SIP server receives a SIP request, it has to decide whether nonces for HTTP Digest authentication will be locally generated in the Diameter client or remotely in the Diameter server. This is a decision derived from a policy that is configured in the SIP server/Diameter server. Note also that if HTTP Digest authentication using AKA [RFC3310] is going to be used, then the only possibility is to generate nonces in the Diameter server. Section 5.6 provides an example of a configuration to address this scenario. Section 10.1 provides further normative details. Note that this memo does not mandate procedures for the SIP server/ Diameter client with respect actions taken with SIP. Therefore, the support for client-generated nonces does not require, in general, extra explanations. 5.3. Diameter Server Authenticates the User, nonce generated in the Diameter server This is the generic mechanism to authenticate users where nonces are generated in the Diameter server as well. In this approach we show an example of an administrative network where the Diameter server is Garcia-Martin, et al. Expires March 25, 2006 [Page 9] Internet-Draft Diameter SIP Application September 2005 both generating nonces and authenticating SIP user requests. This could be the case of a medium size network where the Diameter server is keeping user records and authenticating SIP requests to perform a certain transaction. We have chosen to show a SIP REGISTER request in the example, but the SIP server could request authentication of any other SIP request. Garcia-Martin, et al. Expires March 25, 2006 [Page 10] Internet-Draft Diameter SIP Application September 2005 +--------+ +--------+ +--------+ | SIP | |Diameter| | SIP | |server 1| | server | |server 2| +--------+ +--------+ +--------+ | | | 1. SIP REGISTER | | | -------------------->| 2. UAR | | |------------------>| | | 3. UAA | | |<------------------| | | 4. SIP REGISTER | |-------------------------------------->| | | 5. MAR | | |<------------------| | | 6. MAA | | |------------------>| | 7. SIP 401 (Unauthorized) | 8. SIP 401 (Unauth.) |<--------------------------------------| <--------------------| | | 9. SIP REGISTER | | | -------------------->| 10. UAR | | |------------------>| | | 11. UAA | | |<------------------| | | 12. SIP REGISTER | |-------------------------------------->| | | 13. MAR | | |<------------------| | | 14. MAA | | |------------------>| | 15. SIP 200 (OK) | 16. SIP 200 (OK) |<--------------------------------------| <--------------------| | | | | 17. SAR | | |<------------------| | | 18. SAA | | |------------------>| | | | Figure 2: Authentication performed in the Diameter server According to Figure 2 a SIP User Agent Client (UAC) sends a SIP REGISTER request (step 1) to SIP server 1, which will receive the SIP request. We assume that this SIP server may be located, e.g., at the edge of the administrative home domain. The Diameter client in SIP server 1 will contact its Diameter server by sending a Diameter User- Authorization-Request (UAR) message (step 2) to determine if this user is allowed to receive service, and if so, request the address of Garcia-Martin, et al. Expires March 25, 2006 [Page 11] Internet-Draft Diameter SIP Application September 2005 a local SIP server capable of handling this user. The Diameter server will answer with a Diameter User-Authorization-Answer (UAA) message (step 3), which will indicate either a list of capabilities that SIP server 1 may use to select an appropriate SIP server (SIP server 2) and/or a SIP or SIPS URI pointing to SIP server 2. SIP server 1 will forward the SIP REGISTER request (step 4) to an appropriate SIP server (SIP server 2). The Diameter client in SIP server 2 will then request user authentication from the Diameter server by sending a Diameter Multimedia-Auth-Request (MAR) message (step 5). This request will also serve to make the Diameter server aware of the SIP or SIPS URI of SIP server 2, so as to return subsequent requests for the same user to the same SIP server 2. The Diameter server will respond with a Diameter Multimedia-Auth-Answer (MAA) message (step 6) with Result-Code AVP set to the value DIAMETER_MULTI_ROUND_AUTH. The Diameter server will also generate a nonce and include in the MAA message a challenge, which SIP server 2 will use to map into the WWW-authentication header in the SIP 401 (Unauthorized) response (step 7), which is sent back to SIP server 1 and then to the SIP UAC (step 8). SIP server 1 will receive a next SIP REGISTER request containing the user credentials (step 9). Note that SIP server 1 does not need to keep a state, and even more, there is no guarantee that the SIP request will arrive at the same SIP server 1, there could be a farm of SIP servers 1 operating in redundant configuration. The Diameter client in SIP server 1 will contact a Diameter server by sending a Diameter UAR message (step 10) to determine the SIP server allocated to the user. The Diameter server will send the SIP or SIPS URI of SIP server 2 in a Diameter UAA message (step 11). SIP server 1 will then forward the SIP REGISTER request to SIP server 2 (step 12). SIP server 2 will extract the credentials from the SIP REGISTER request. The Diameter client in SIP server 2 will send those credentials in a Diameter MAR message (step 13) to the Diameter server. At this point, the Diameter server will be able to authenticate the user, and upon success, will return a Diameter MAA message (step 14) with the AVP Result-Code set to the value DIAMETER_SUCCESS. SIP server 2 will then generate a SIP 200 (OK) response (step 15) which is forwarded to SIP server 1 and eventually to the SIP UAC (step 16). If the Diameter client in SIP server 2 is interested in downloading the user profile information or requires to store the address of the SIP server in the Diameter server, then the Diameter client will send a Diameter SAR message (step 17) to the Diameter server. The Garcia-Martin, et al. Expires March 25, 2006 [Page 12] Internet-Draft Diameter SIP Application September 2005 Diameter server will reply with a Diameter SAA message (step 18) that contains the requested user profile information and the acknowledgement of the SIP server address storage. These actions are needed when the SIP server needs to retrieve a user profile used to provide services to the served user or when the SIP server will keep a state for the user, so the Diameter server needs to store its address. 5.4. Delegating Final Authentication Check to the SIP Server, nonce generated in the Diameter server An operator with a large base of installed SIP servers may wish to minimize the number of round trips between the Diameter client and the Diameter server. We provide support for a mechanism where nonces are generated in the Diameter server, but the Diameter server delegates the final authentication check to the SIP server, saving a round trip. It must noted that this scenario is applicable when the Diameter server is configured to use the MD5 Message-Digest algorithm in the HTTP Digest authentication. If the Diameter server is configured to use a session MD5 (MD5-sess) algorithm, then the Diameter server requires the client nonce to compute the H(A1) before sending it to the Diameter client, and the client nonce might not be available at this time. Garcia-Martin, et al. Expires March 25, 2006 [Page 13] Internet-Draft Diameter SIP Application September 2005 +--------+ +--------+ +--------+ | SIP | |Diameter| | SIP | |server 1| | server | |server 2| +--------+ +--------+ +--------+ | | | 1. SIP REGISTER | | | -------------------->| 2. UAR | | |------------------>| | | 3. UAA | | |<------------------| | | 4. SIP REGISTER | |-------------------------------------->| | | 5. MAR | | |<------------------| | | 6. MAA | | |------------------>| | 7. SIP 401 (Unauthorized) | 8. SIP 401 (Unauth.) |<--------------------------------------| <--------------------| | | 9. SIP REGISTER | | | -------------------->| 10. UAR | | |------------------>| | | 11. UAA | | |<------------------| | | 12. SIP REGISTER | |-------------------------------------->| | | 13. SAR | | |<------------------| | | 14. SAA | | |------------------>| | 15. SIP 200 (OK) | 16. SIP 200 (OK) |<--------------------------------------| <--------------------| | | | | | Figure 3: Delegation of authentication to the SIP server, nonce generated in the Diameter server Figure 3 shows an example where a SIP server is dynamically allocated to serve a SIP User Agent with the support of the Diameter server. This may be the case of certain architectures, such as that of the 3rd Generation Partnership Project (3GPP) IP Core Network Multimedia Subsystem (IMS). A first SIP server receives a SIP REGISTER request (step 1) whose target is the home network domain. We assume that this SIP server may be located, e.g., at the edge of the administrative home domain. The Diameter client in this SIP server requests authorization from Garcia-Martin, et al. Expires March 25, 2006 [Page 14] Internet-Draft Diameter SIP Application September 2005 the Diameter server to proceed with the registration, by sending a Diameter User-Authorization-Request (UAR) message (step 2). The message includes, among other Attribute-Value-Pairs (AVP), the SIP address-of-record that is included in the SIP REGISTER request. The Diameter server will verify the SIP address-of-record and, if it is a valid defined user in the home network, will authorize the registration to proceed. The Diameter server will respond with a Diameter User-Authorization-Answer (UAA) message (step 3), which will inform the Diameter client/SIP server about the result of the user authorization. In case of a successful authorization, the Diameter UAA message will indicate either the address of a local SIP server (SIP server 2 in Figure 3) and/or a list of capabilities that SIP server 1 may use to select an appropriate SIP server 2. When the authorization is successful, SIP server 1 will forward the SIP REGISTER request (step 4) to the appropriate SIP server (SIP server 2). The Diameter client in SIP server 2 first takes a decision, based on configuration, whether to operate in the mode where nonces are generated in the Diameter client or in the Diameter server will then request authentication parameters by sending a Diameter Multimedia-Auth-Request (MAR) message (step 5) to the Diameter server. This request will also serve to make the Diameter server aware of the SIP or SIPS URI of SIP server 2, so as to return subsequent requests of the same user to the same SIP server 2. The Diameter server will respond with a Diameter Multimedia-Auth-Answer (MAA) message (step 6), which will include a nonce and all the rest of parameters necessary for the designated authentication algorithm associated with the user. Among others, the MAA message will include a Digest-HA1 AVP that contains H(A1) (as defined in RFC 2617 [RFC2617]), and allows the Diameter client to calculate the expected response. Then the Diameter client can use this expected response to compare it with the response to the challenge sent from the SIP UA. If the Digest-HA1 AVP is not present in MAA, it indicates that authentication and authorization will take place in the Diameter server, as per the scenario described in Section 5.3. SIP server 2 will then create a SIP 401 (Unauthorized) SIP response (step 7) based on the challenge included in the MAA message, including the authentication material needed by the SIP User Agent Client (UAC) to include the appropriate credentials. SIP server 1 forwards the SIP response to the SIP UAC (step 8). When SIP server 1 receives a next SIP REGISTER request containing the user credentials (step 9), as SIP server 1 does not need to keep a state (even there is no guarantee that the SIP request arrives to the same SIP server 1), the Diameter client in SIP server 1 will contact again the Diameter server by sending a Diameter UAR message (step 10) to determine the SIP server allocated to the user. The Diameter Garcia-Martin, et al. Expires March 25, 2006 [Page 15] Internet-Draft Diameter SIP Application September 2005 server will send the SIP or SIPS URI of SIP server 2 in a Diameter UAA message (step 11). SIP server 1 will then forward the SIP REGISTER request to SIP server 2 (step 12). SIP server 2 will validate the credentials by comparing the response supplied by the SIP UA with the expected response calculated by the SIP server 2 (based on the H(A1) received from the Diameter server). If the credentials are valid, SIP server 2 will send a Diameter Server-Assignment-Request (SAR) message (step 13) requesting the Diameter server to confirm the completion of the authentication procedure and to confirm the SIP or SIPS URI of the SIP server that is currently serving the user. The Diameter SAR message also serves the purpose to request the Diameter server to send the user profile to the SIP server. The Diameter server will respond with a Diameter Server-Assignment-Answer (SAA) message (step 14). If the Result-Code AVP value does not inform about an error, the SAA message can include zero or more SIP-User-Data AVPs containing the information that SIP server 2 needs in order to provide a service to the user. SIP server 2 generates a SIP 200 (OK) response (step 15) that will be forwarded to SIP server 1 and eventually to the SIP UAC (step 16). 5.5. SIP Server Requests Authentication and Authorization, nonce generated in the Diameter server Figure 4 depicts a typical scenario where a stateless SIP proxy requests authentication information and authorization to a Diameter server, for the purpose of providing SIP routing services to a SIP User Agent. The SIP proxy server may be configured as an outbound SIP proxy, so that all the requests initiated by the SIP UA traverse the SIP proxy. In this scenario nonces are generated in the Diameter server. According to Figure 4, a SIP User Agent sends a SIP request to its outbound SIP proxy server. In this case, the message is a SIP INVITE request (see step 1), but it could be any other SIP request. We assume that this SIP request does not contain any credentials at this time. The outbound SIP proxy server needs to authenticate and authorize the proxy services offered to the user. The Diameter client in the SIP server sends a Multimedia-Auth-Request (MAR) message (step 2). The Diameter server generates a nonce and sends a Multimedia-Auth-Answer (MAA) message (step 3) that includes the nonce and all the rest of the data necessary for the SIP server to challenge the user, typically with HTTP Digest Authentication indicated in the MAA message. This data will serve the SIP server to create a SIP 407 (Proxy Authentication Required) response (step 4) Garcia-Martin, et al. Expires March 25, 2006 [Page 16] Internet-Draft Diameter SIP Application September 2005 that contains a challenge. The SIP UA will create a new INVITE request (step 5) that contains the credentials. The Diameter client in the SIP server will send the credentials to the Diameter server in a new Diameter MAR message (step 6). The Diameter server will validate the credentials and authorize the SIP transaction in a Diameter MAA message (step 7). The SIP server forwards the SIP INVITE request to its destination (step 8) as per regular SIP procedures. Eventually, the session setup will be confirmed with a SIP 200 (OK) response (step 9) that is forwarded to the SIP UA (step 10). The session setup is complete. +--------+ +--------+ |Diameter| | SIP | | server | | server | +--------+ +--------+ | | | | 1. SIP INVITE | ----------------------------------->| | 2. MAR | |<------------------| | 3. MAA | |------------------>| | | 4. SIP 407 (Proxy | Authentication Required) | <-----------------------------------| | | 5. SIP INVITE | ----------------------------------->| | 6. MAR | |<------------------| | 7. MAA | |------------------>| 8. SIP INVITE | |----------------> | | 9. SIP 200 (OK) 10. SIP 200 (OK) |<---------------- <-----------------------------------| | | Figure 4: SIP server requests authorization, nonce generated in the Diameter server 5.6. SIP Server Requests Authentication and Authorization, nonce generated in the Diameter client Figure 5 presents a variation of the scenario introduced in Section 5.5, where now the nonce is generated in the Diameter client Garcia-Martin, et al. Expires March 25, 2006 [Page 17] Internet-Draft Diameter SIP Application September 2005 rather than the Diameter server. This scenario saves a round trip compared to the one in Section 5.5, although ths scenario is not compatible with HTTP Digest authentication using AKA [RFC3310]. According to Figure 5, a SIP User Agent sends a SIP request to its outbound SIP proxy server. We assume that this SIP request does not contain any credentials at this time. The Diameter client locally generates a nonce and, together with the rest of the data, creates a challenge that is sent in a SIP 407 (Proxy Authentication Required) response (step 2). The SIP UA will create a new INVITE request (step 3) that contains the credentials. The Diameter client in the SIP server will send the credentials to the Diameter server in a new Diameter MAR message (step 4). The Diameter server will validate the credentials and authorize the SIP transaction in a Diameter MAA message (step 5). The SIP server forwards the SIP INVITE request to its destination (step 6) as per regular SIP procedures. Eventually, the session setup will be confirmed with a SIP 200 (OK) response (step 7) that is forwarded to the SIP UA (step 8). The session setup is complete. +--------+ +--------+ |Diameter| | SIP | | server | | server | +--------+ +--------+ | | | | 1. SIP INVITE | ----------------------------------->| | | 2. 407 Proxy Authentication Required) | <-----------------------------------| | | 3. SIP INVITE | ----------------------------------->| | 4. MAR | |<------------------| | 5. MAA | |------------------>| 6. SIP INVITE | |----------------> | | 8. SIP 200 (OK) 8. SIP 200 (OK) |<---------------- <-----------------------------------| | | Figure 5: SIP server requests authorization, nonce generated in the Diameter client Garcia-Martin, et al. Expires March 25, 2006 [Page 18] Internet-Draft Diameter SIP Application September 2005 5.7. Locating the recipient of the SIP request Figure 6 shows the scenario where SIP server 1 may be configured as a SIP edge proxy server, processing SIP traffic at the edge of a network. SIP server 1 receives a SIP INVITE request (step 1). SIP server 1 needs to find the address of SIP server 2, which is serving the recipient of the SIP request. The Diameter client in SIP server 1 sends Diameter Location-Info-Request (LIR) message (step 2) to the Diameter server. The Diameter server responds with a Diameter Location-Info-Answer (LIA) message (step 3) that contains the SIP or SIPS URI of SIP server 2. SIP server 1 then forwards the SIP INVITE to SIP server 2 (step 4). SIP server 2 will eventually forward the SIP INVITE to the appropriate UAS (step 5). +--------+ +--------+ +--------+ | SIP | |Diameter| | SIP | |server 1| | server | |server 2| +--------+ +--------+ +--------+ | | | 1. SIP INVITE | | | -------------->| 2. LIR | | |---------------->| | | 3. LIA | | |<----------------| | | 4. SIP INVITE | |--------------------------------->| | | | 5. SIP INVITE | | |--------------> | | | | | | Figure 6: Locating the SIP server of the recipient Although the example shows the connection between a SIP INVITE request and the Diameter LIR message, any other SIP request other than REGISTER (such as SUBSCRIBE, OPTIONS, etc.) would trigger the same Diameter message (A SIP REGISTER request will trigger a Diameter UAR message, as indicated in Figures Figure 2 and Figure 3. The scenario described in this section is also applicable in case an outbound SIP server is interested not in authenticating the user, but requires to locate a further SIP server to route the outbound SIP requests. In this case, the outbound SIP server is mapped to SIP server 1 in Figure 6. 5.8. Update of the User Profile The Diameter SIP application provides a mechanism for a Diameter Garcia-Martin, et al. Expires March 25, 2006 [Page 19] Internet-Draft Diameter SIP Application September 2005 server to asynchronously download a user profile to a SIP server whenever there is an update of such user profile. It must be noted that the Diameter server also attaches the user profile in the Diameter Server-Assignment-Answer (SAA) message. Although this is valid for most of the daily situations, it may happen that the administrator decides to update or modify the user profile for a particular user, due to, e.g., new services made available to the user. This may involve mechanisms outside the scope of this specification, such as human intervention, in the Diameter server. In this situation, the Diameter server is able to push the new user profile into the SIP server allocated to the user. The scenario is illustrated in Figure 7. Where the user profile changes, the Diameter server will send a Diameter Push-Profile- Request (PPR) message (step 1) to the Diameter client in the SIP server allocated to that user (SIP server 2 in the examples). The Diameter PPR message will contain one or more SIP-User-Data AVP, a User-Name AVP and zero or more SIP-AOR AVPs. The Diameter client in SIP server 2 will acknowledge the Diameter PPR message by sending a Diameter Push-Profile-Answer (PPA) message (step 2) to the Diameter server. +--------+ +--------+ |Diameter| | SIP | | server | |server 2| +--------+ +--------+ | | | 1. PPR | |------------------>| | | | 2. PPA | |<------------------| | | Figure 7: Diameter server pushes an update of the user profile 5.9. SIP Soft State Termination SIP can create soft states in SIP nodes based on, e.g., SIP registrations or SIP event subscriptions. These states are periodically refreshed, and cease to exist if they are not refreshed. Additionally, an administrative action can be taken to terminate a SIP soft state, or the SIP UA can explicitly terminate a SIP soft state. The Diameter base protocol offers a mechanism to create and delete states in Diameter nodes. These states are called Diameter user sessions. The Diameter server decides whether to use a Diameter user Garcia-Martin, et al. Expires March 25, 2006 [Page 20] Internet-Draft Diameter SIP Application September 2005 session as a mechanism to map to a SIP soft state. If the Diameter server decides to use Diameter user sessions, the termination of a Diameter user session implies the termination of the corresponding SIP soft state (e.g., registration, event subscription), and vice versa. If the Diameter server does not use Diameter user sessions, this Diameter SIP application offers specific commands to manage the SIP soft states. Implementations compliant to this specification MUST support both mechanisms of session management. We provide support for both Diameter client and Diameter server initiated session termination. Depending on whether Diameter sessions are used or not, termination of a SIP soft state can be achieved by either of the following methods: When the Diameter client (SIP proxy) wants to terminate the SIP soft state and Diameter user sessions are not maintained (i.e., the Auth- Session-State AVP has been previously set to NO_STATE_MAINTAINED), the Diameter client MUST send a Server-Assignment-Request (SAR) message with the SIP-Server-Assignment-Type AVP set to the value DE- REGISTRATION. When the Diameter client (SIP proxy) wants to terminate the SIP soft state and Diameter user sessions are maintained (i.e., the Auth- Session-State AVP has been previously set to STATE_MAINTAINED) the Diameter client MUST send a Session-Termination-Request message as per regular procedures according to the RFC 3588 [RFC3588]. When the Diameter server wants to terminate the SIP soft state and Diameter user sessions are not maintained (i.e., the Auth-Session- State AVP has been previously set to NO_STATE_MAINTAINED), the Diameter server MUST send a Registration-Termination-Request message (see Section 7.9). When the Diameter server wants to terminate the SIP soft state and Diameter user sessions are maintained (i.e., the Auth-Session-State AVP has been previously set to STATE_MAINTAINED), the Diameter server MUST send an Abort-Session-Request message as per regular procedures according to the RFC 3588 [RFC3588]. 5.10. Diameter Server Discovery The basic architecture assumption of this document is that all the data related to a user is stored in a unique Diameter server. This does not create a single point of failure, as it may be generally thought. It is assumed that Diameter servers will be configured in a redundant fashion as an attempt to mitigate the single point of Garcia-Martin, et al. Expires March 25, 2006 [Page 21] Internet-Draft Diameter SIP Application September 2005 failure problem. In large networks, where the number of users may be significantly high, there might be a need to scale the number of Diameter servers. All the data associated with a user will be still stored in one Diameter server (typically operating in a redundant configuration). But the data associated with different users may reside in different Diameter servers. This configuration, although scales well, introduces a new problem, namely: given the user's SIP AOR as an input, how to determine which of various Diameter servers is storing the data for that particular SIP AOR. We solve this problem by inspiring on the Diameter redirection mechanism specified in RFC 3588 [RFC3588]. We include in the architecture a new Diameter node that, for the purpose of this document, it is known as Diameter Subscriber Locator (SL). The Diameter Subscriber Locator contains a database or routing tables that maps SIP AORs with Diameter server URIs. A particular Diameter server URI points to the actual Diameter server that stores all the data related to a particular SIP AOR, and in consequence, to the user who owns the SIP AOR. The Diameter Subscriber Locator acts in a similar way to a Diameter Redirect Agent, dispatching Diameter requests (e.g., providing the redirection URI in the answer). The Diameter Subscriber Locator can redirect all the request pertaining to a user by setting the Redirect-Host-Usage AVP with a value ALL_USER, as specified in RFC 3588 [RFC3588]. The Diameter SL can be replicated in different nodes along the network, for the purpose of building scalability and redundancy. The database or routing tables have to be consistent across all these different Diameter SLs, so that equal Diameter requests will produce the equal Diameter answers no matter which Diameter SL processes the request. Garcia-Martin, et al. Expires March 25, 2006 [Page 22] Internet-Draft Diameter SIP Application September 2005 +--------+ +--------+ +--------+ +--------+ | SIP | |Diameter| |Diameter| | SIP | |server 1| |SL red. | |server 1| |server 2| +--------+ +--------+ +--------+ +--------+ | | | | 1. SIP INVITE| | | | ------------>| 2. LIR | | | |---------->| | | | 3. LIA | | | |<----------| | | | 4. LIR | | |---------------------->| | | 5. LIA | | |<----------------------| | | 6. SIP INVITE | | |----------------------------------->| 7. SIP INVITE | | | | -------------> | | | | Figure 8: Locating a Diameter server. SL redirecting requests Figure 8 shows an example of operation of a Diameter Subscriber Locator acting in redirect mode. SIP server 1 is receiving an INVITE request (step 1) addressed (in the SIP Request-URI) to a user for which the Diameter client in SIP server 1 does not posses routing information. In other words, the Diameter client in SIP server 1 does not know the URI of Diameter server 1. The Diameter client sends a Diameter LIR message (step 2) to any of the Diameter SLs configured in the network. The address of those SLs is assumed to be pre-provisioned in the Diameter client. The Diameter SL, based on the contents of the SIP-AOR AVP and its own routing tables determines the Diameter server that stores the information allocated to such user. Then it builds a Diameter LIA message (step 3) that includes a Result-Code AVP set to DIAMETER_REDIRECT_INDICATION and one or more Redirect-Host AVPs, whose values are set to one or more URIs of Diameter servers that store the information related to such user. Then the Diameter client in SIP server 1 builds a new LIR message (step 4) addressed to any of the Diameter servers received in the Redirect-Host AVPs. The rest of procedure is completed as described in previous sections. 6. Advertising Application Support Diameter implementations conforming to this specification MUST advertise its support by including an Auth-Application-Id AVP in the Capabilities-Exchange-Request (CER) and Capabilities-Exchange-Answer Garcia-Martin, et al. Expires March 25, 2006 [Page 23] Internet-Draft Diameter SIP Application September 2005 (CEA) commands, according to the Diameter base protocol, RFC 3588 [RFC3588]. This Auth-Application-Id AVP MUST be set to the value of this Diameter SIP application (Section 12.1 indicates the actual value allocated by IANA). 7. Diameter SIP Application Command Codes All the Diameter implementations conforming to this specification MUST implement and support the list of Diameter commands listed in Table 1. +-------------------------------------+-------+------+--------------+ | Command Name | Abbr. | Code | Reference | +-------------------------------------+-------+------+--------------+ | User-Authorization-Request | UAR | aaa | Section 7.1 | | User-Authorization-Answer | UAA | aaa | Section 7.2 | | Server-Assignment-Request | SAR | bbb | Section 7.3 | | Server-Assignment-Answer | SAA | bbb | Section 7.4 | | Location-Info-Request | LIR | ccc | Section 7.5 | | Location-Info-Answer | LIA | ccc | Section 7.6 | | Multimedia-Auth-Request | MAR | ddd | Section 7.7 | | Multimedia-Auth-Answer | MAA | ddd | Section 7.8 | | Registration-Termination-Request | RTR | eee | Section 7.9 | | Registration-Termination-Answer | RTA | eee | Section 7.10 | | Push-Profile-Request | PPR | fff | Section 7.11 | | Push-Profile-Answer | PPA | fff | Section 7.12 | +-------------------------------------+-------+------+--------------+ Table 1: Defined command codes [Note to IANA and the RFC editor: replace aaa, bbb, ccc, and so on with the actual values allocated to these commands.] 7.1. User-Authorization-Request (UAR) Command The User-Authorization-Request (UAR) is indicated by the Command-Code set to aaa [Note to IANA and the RFC editor: replace aaa with the actual value allocated to this command] and the Command Flags' 'R' bit set. The Diameter client in a SIP server sends this command to the Diameter server to request authorization for the SIP User Agent to route a SIP REGISTER request. As the SIP REGISTER request implicitly carries a permission to bind an AOR to a contact address, the Diameter client uses the Diameter UAR as a first authorization request towards the Diameter server to authorize the registration. For instance, the Diameter server can verify that the AOR is a legitimate user of the realm. Garcia-Martin, et al. Expires March 25, 2006 [Page 24] Internet-Draft Diameter SIP Application September 2005 The Diameter client in the SIP server will request authorization for one of the possible values defined in the SIP-User-Authorization-Type AVP (Section 8.10). The user name used for authentication of the user is conveyed in a User-Name AVP (defined in the Diameter base protocol, RFC 3588 [RFC3588]). The location of the authentication user name in the SIP REGISTER request varies depending on the authentication mechanism. When the authentication mechanism is HTTP Digest as defined in RFC 2617 [RFC2617], the authentication user name is found in the "username" directive of the SIP Authorization header field value. This Diameter SIP application only provides support for HTTP Digest authentication in SIP: other authentication mechanisms are not currently supported. The SIP or SIPS URI to be registered is conveyed in the SIP-AOR AVP (Section 8.8). Typically this SIP or SIPS URI is found in the To header field value of the SIP REGISTER request that triggered the Diameter UAR message. The SIP-Visited-Network-Id AVP indicates the network that is providing SIP services (e.g., SIP proxy functionality or any other kind of services) to the SIP User Agent. Message Format ::= < Diameter Header: aaa, REQ, PXY > < Session-ID > < Auth-Application-Id > { Auth-Session-State } { Origin-Host } { Origin-Realm } { Destination-Realm } { SIP-AOR } [ Destination-Host ] [ User-Name ] [ SIP-Visited-Network-Id ] [ SIP-User-Authorization-Type ] * [ Proxy-Info ] * [ Route-Record ] * [ AVP ] [Note to IANA and the RFC editor: replace aaa with the actual value allocated to this command] 7.2. User-Authorization-Answer (UAA) Command The User-Authorization-Answer (UAA) is indicated by the Command-Code set to aaa [Note to IANA and the RFC editor: replace aaa with the Garcia-Martin, et al. Expires March 25, 2006 [Page 25] Internet-Draft Diameter SIP Application September 2005 actual value allocated to this command] and the Command Flags' 'R' bit cleared. The Diameter server sends this command in response to a previously received Diameter User-Authorization-Request (UAR) command. The Diameter server indicates the result of the requested registration authorization. Additionally, the Diameter server may indicate a collection of SIP capabilities that assists the Diameter client to select a SIP proxy to the AOR under registration. In addition to the values already defined in RFC 3588 [RFC3588], the Result-Code AVP may contain one of the values defined in Section 9.1. Whenever the Diameter server fails to process the Diameter UAR message, it MUST stop processing and return the concerned error in the Diameter UAA message. When there is success in the process, the Diameter server MUST set the code to DIAMETER_SUCCESS in the Diameter UAA message. If the Diameter server requires a User-Name AVP value to process the Diameter UAR request, but the Diameter UAR message did not contain a User-Name AVP value, the Diameter server MUST set the Result-Code AVP value to DIAMETER_USER_NAME_REQUIRED (see Section 9.1.2) and return it in a Diameter UAA message. Upon reception of this Diameter UAA message with the Result-Code AVP value set to DIAMETER_USER_NAME_REQUIRED, the SIP server will typically request authentication by generating a SIP 401 (Unauthorized) or SIP 407 (Proxy Authentication Required) response back to the originator. When the authorization procedure succeeds, the Diameter server constructs a User-Authorization-Answer (UAA) message that MUST include the address of the SIP server already assigned to the user, the capabilities needed by the SIP server (Diameter client) to select another SIP server for the user or a combination of the previous two options. The Diameter UAA message contains the address of the SIP server allocated to the user if the Diameter server is already aware of an allocated SIP server to the user. The Diameter UAA message contains the capabilities required by a SIP server when there is a possibility that the Diameter client (in the SIP server) needs to allocate another SIP server that will be handling all the requests associated with this user, and possibly triggering and executing services. If a User-Name AVP is present in the Diameter UAR message, then the Diameter server MUST verify the existence of the user in the realm, i.e., the User-Name AVP value is a valid user within that realm. If the Diameter server does not recognize the user name received in the Garcia-Martin, et al. Expires March 25, 2006 [Page 26] Internet-Draft Diameter SIP Application September 2005 User-Name AVP, the Diameter server MUST build a Diameter User- Authorization-Answer (UAA) message and MUST set the Result-Code AVP to DIAMETER_ERROR_USER_UNKNOWN. If a User-Name AVP is present in the Diameter UAR message, then the Diameter server MUST authorize that User-Name AVP value is able to register the SIP or SIPS URI included in the SIP-AOR AVP. If this authorization fails, the Diameter server must set the Result-Code AVP to DIAMETER_ERROR_IDENTITIES_DONT_MATCH and send it in a Diameter User-Authorization-Answer (UAA) message. Correlation between User-Name and SIP-AOR AVP values is required just to avoid that any user can register a SIP-AOR allocated to another user. If there is a SIP-Visited-Network-Id AVP in the Diameter UAR message, and the SIP-User-Authorization-Type AVP value received in the Diameter UAR message is set to REGISTRATION or REGISTRATION& CAPABILITIES then the Diameter server SHOULD verify whether the user is allowed to roam into the network specified in the SIP-Visited- Network-Id AVP in the Diameter UAR message. If the user is not allowed to roam into such network, the Diameter AAA server MUST set the Result-Code AVP value in the Diameter UAA message to DIAMETER_ERROR_ROAMING_NOT_ALLOWED. If the SIP-User-Authorization-Type AVP value received in the Diameter UAR message is set to REGISTRATION or REGISTRATION&CAPABILITIES then the Diameter server SHOULD verify whether the SIP-AOR AVP value is authorized to register in the home realm. Where the SIP Address of Record is not authorized to register in the home realm, the Diameter server MUST set the Result-Code AVP to DIAMETER_AUTHORIZATION_REJECTED and send it in a Diameter UAA message. When the SIP-User-Authorization-Type AVP is not present in the Diameter UAR message, or it is present and its value is set to REGISTRATION then: o If the Diameter server is not aware of any previous registration of the user name (including registrations of other SIP Addresses of Record allocated to the same user name), then the Diameter server does not know of any SIP server allocated to the user. In this case the Diameter server MUST set the Result-Code AVP value to DIAMETER_FIRST_REGISTRATION in the Diameter UAA message, and the Diameter server SHOULD include the required SIP server capabilities in the SIP-Server-Capabilities AVP value in the Diameter UAA message. The SIP-Server-Capabilities AVP will assist the Diameter client (SIP server) to select an appropriate SIP Garcia-Martin, et al. Expires March 25, 2006 [Page 27] Internet-Draft Diameter SIP Application September 2005 server for the user, according to the required capabilities. o In some cases, the Diameter server is aware of a previously assigned SIP server for the same or different SIP Addresses of Record allocated to the same user name. In these cases, re- assignment of a new SIP server may or may not be needed, depending on the capabilities of the SIP server. The Diameter server MUST always include the allocated SIP server URI in the SIP-Server-URI AVP of the UAA message. If the Diameter server does not return the SIP capabilities, the Diameter server MUST set the Result-Code AVP in the Diameter UAA message to DIAMETER_SUBSEQUENT_REGISTRATION. Otherwise, if the Diameter server includes a SIP-Server-Capabilities AVP then the Diameter server MUST set the Result-Code AVP in the Diameter UAA message to DIAMETER_SERVER_SELECTION. The Diameter client will then determine, based on the received information, whether it needs to select a new SIP server or not. When the SIP-User-Authorization-Type AVP value received in the Diameter UAR message is set to REGISTRATION&CAPABILITIES then Diameter Server MUST return the list of capabilities in the SIP- Server-Capabilities AVP value of the Diameter UAA message, it MUST set the Result-Code to DIAMETER_SUCCESS and it MUST NOT return a SIP- Server-URI AVP. The SIP-Server-Capabilities AVP enables the SIP server (Diameter Client) to select another appropriate SIP server for invoking and executing services for the user, depending on the required capabilities. The Diameter server MAY leave the list of capabilities empty to indicate that any SIP server can be selected. When the SIP-User-Authorization-Type AVP value received in the Diameter UAR message is set to DE-REGISTRATION then: o If the Diameter server is aware of a SIP server assigned to the SIP AOR under de-registration, the Diameter server MUST set the Result-Code AVP to DIAMETER_SUCCESS and MUST set the SIP-Server- URI AVP value to the known SIP server, and return them in the Diameter UAA message. o If the Diameter server is not aware of a SIP server assigned to the SIP AOR under de-registration, then the Diameter server MUST set the Result-Code AVP in the Diameter UAA message to DIAMETER_ERROR_IDENTITY_NOT_REGISTERED. Garcia-Martin, et al. Expires March 25, 2006 [Page 28] Internet-Draft Diameter SIP Application September 2005 Message Format ::= < Diameter Header: aaa, PXY > < Session-Id > { Auth-Application-Id } { Auth-Session-State } { Result-Code } { Origin-Host } { Origin-Realm } [ SIP-Server-URI ] [ SIP-Server-Capabilities ] [ Authorization-Lifetime ] [ Auth-Grace-Period ] * [ Redirect-Host ] [ Redirect-Host-Usage ] [ Redirect-Max-Cache-Time ] * [ Proxy-Info ] * [ Route-Record ] * [ AVP ] [Note to IANA and the RFC editor: replace aaa with the actual value allocated to this command] 7.3. Server-Assignment-Request (SAR) Command The Server-Assignment-Request (SAR) command is indicated by the Command-Code set to bbb [Note to IANA and the RFC editor: replace bbb with the actual value allocated to this command] and the Command Flags' 'R' bit set. The Diameter client in a SIP server sends this command to the Diameter server to indicate the completion of the authentication process and to request the Diameter server to store the URI of the SIP server that is currently serving the user. The Diameter SAR command has the main function to inform and store/clear in the Diameter server the URI of the SIP server allocated to the user. Additionally, the Diameter client can request to download the user profile or part of it. During the registration procedure, a SIP server becomes assigned to the user. The Diameter client in the assigned SIP server MUST include its own URI in the SIP-Server-URI AVP of the Server- Assignment-Request (SAR) Diameter message and send it to the Diameter server. The Diameter server then becomes aware of the allocation of the SIP server and its URI. The Diameter client in the SIP server MAY send a Diameter SAR message because of other reasons. These reasons are identified in the SIP- Server-Assignment-Type AVP value (Section 8.4). For instance, a Diameter client in a SIP server may contact the Diameter server to request de-registration of a user, to inform the Diameter server of Garcia-Martin, et al. Expires March 25, 2006 [Page 29] Internet-Draft Diameter SIP Application September 2005 an authentication failure or just to download the user profile. For a complete description of all the SIP-Server-Assignment-Type AVP values see Section 8.4. Typically the reception of a SIP REGISTER request in a SIP server will trigger the Diameter client in the SIP server to send the Diameter SAR message. However, if a SIP server is receiving other SIP request, such as INVITE, and the SIP server does not have the user profile, the Diameter client in the SIP server may send the Diameter SAR message to the Diameter server in order to download the user profile and make the Diameter server aware of the SIP server assigned to the user. The user profile is an important piece of information that dictates the behavior of the SIP server when triggering or providing services for the user. Typically the user profile is divided into: o Services to be rendered to the user when the user is registered and initiates a SIP request. o Services to be rendered to the user when the user is registered and a SIP request destined to that user arrives to the SIP proxy. o Services to be rendered to the user when the user is not registered and a SIP request destined to that user arrives to the SIP proxy. The SIP-Server-Assignment-Type AVP will indicate the reason why the Diameter client (SIP server) contacted the Diameter server. If the Diameter client sets the SIP-Server-Assignment-Type AVP value to REGISTRATION, RE_REGISTRATION, UNREGISTERED_USER, NO_ASSIGNMENT, AUTHENTICATION_FAILURE or AUTHENTICATION_TIMEOUT, the Diameter client MUST include exactly one SIP-AOR AVP in the Diameter SAR message. The SAR message MAY contain zero or more SIP-Supported-User-Data-Type AVPs. Each of them will contain a type of user data understood by the SIP server. This allows the Diameter client to provide an indication to the Diameter server of the different format of user data understood by the SIP server. The Diameter server will use this information to select one more SIP-User-Data AVPs that will be included in the SAA message. Garcia-Martin, et al. Expires March 25, 2006 [Page 30] Internet-Draft Diameter SIP Application September 2005 Message Format ::= < Diameter Header: bbb, REQ, PXY > < Session-Id > { Auth-Application-Id } { Auth-Session-State } { Origin-Host } { Origin-Realm } { Destination-Realm } { SIP-Server-Assignment-Type } { SIP-User-Data-Already-Available } [ Destination-Host ] [ User-Name ] [ SIP-Server-URI ] * [ SIP-Supported-User-Data-Type ] * [ SIP-AOR ] * [ Proxy-Info ] * [ Route-Record ] * [ AVP ] [Note to IANA and the RFC editor: replace bbb with the actual value allocated to this command] 7.4. Server-Assignment-Answer (SAA) Command The Server-Assignment-Answer (SAA) is indicated by the Command-Code set to bbb [Note to IANA and the RFC editor: replace bbb with the actual value allocated to this command] and the Command Flags' 'R' bit cleared. The Diameter server sends this command in response to a previously received Diameter Server-Assignment-Request (SAR) command. The response may include the user profile or part of it, if requested. In addition to the values already defined in RFC 3588 [RFC3588], the Result-Code AVP may contain one of the values defined in Section 9.1. The Result-Code AVP value in the Diameter SAA message may indicate a success or an error in the execution of the Diameter SAR command. If Result-Code AVP value in the Diameter SAA message does not contain an error code, the SAA message MAY include one more SIP-User-Data AVPs that will typically contain the profile of the user, indicating services that the SIP server can provide to that user. The Diameter server MAY include one or more SIP-Supported-User-Data- Type AVPs, each one identifying a type of user data format supported in the Diameter server. If there is not a common supported user data type between the Diameter client and the Diameter server, the Diameter server SHOULD declare its list of supported user data types by including one or more SIP-Supported-User-Data-Type AVPs in a Garcia-Martin, et al. Expires March 25, 2006 [Page 31] Internet-Draft Diameter SIP Application September 2005 Diameter SAA message. This indication is merely for debugging reasons, since there is not a fall-back mechanism that allows the Diameter client to retrieve the profile in a supported format. If the Diameter server requires a User-Name AVP value to process the Diameter SAR request, but the Diameter SAR message did not contain a User-Name AVP value, the Diameter server MUST set the Result-Code AVP value to DIAMETER_USER_NAME_REQUIRED (see Section 9.1.2) and return it in a Diameter SAA message. Upon reception of this Diameter SAA message with the Result-Code AVP value set to DIAMETER_USER_NAME_REQUIRED, the SIP server will typically request authentication by generating a SIP 401 (Unauthorized) or SIP 407 (Proxy Authentication Required) response back to the originator. If the User-Name AVP is included in the Diameter SAR message, at reception of the Diameter SAR message, the Diameter server MUST verify the existence of the user in the realm, i.e., the User-Name AVP value is a valid user within that realm. If the Diameter server does not recognize the user name received in the User-Name AVP, the Diameter server MUST build a Diameter Server-Assignment-Answer (SAA) message and MUST set the Result-Code AVP to DIAMETER_ERROR_USER_UNKNOWN. Then the Diameter server MUST authorize that User-Name AVP value is a valid authentication name for the SIP or SIPS URI included in the SIP-AOR AVP of the Diameter SAR message. If this authorization fails, the Diameter server must set the Result-Code AVP to DIAMETER_ERROR_IDENTITIES_DONT_MATCH and send it in a Diameter Server-Assignment-Answer (SAA) message. The actions of the Diameter server at the reception of the Diameter SAR message depends on the value of the SIP-Server-Assignment-Type: o If the SIP-Server-Assignment-Type AVP value in the Diameter SAR message is set to REGISTRATION or RE_REGISTRATION, the Diameter server SHOULD verify that there is only one SIP-AOR AVP. Otherwise, the Diameter server MUST answer with a Diameter SAA message with the Result-Code AVP value set to DIAMETER_AVP_OCCURS_TOO_MANY_TIMES and MUST NOT include any SIP- User-Data AVP. If there is only one SIP-AOR AVP and if the SIP- User-Data-Already-Available AVP value is set to USER_DATA_NOT_AVAILABLE, then the Diameter server SHOULD include one or more user profile data with the SIP or SIPS URI (SIP-AOR AVP) and all other SIP identities associated with that AVP in the SIP-User-Data AVP value of the Diameter SAA message. On selecting the type of user data, the Diameter server SHOULD take into account the supported formats at the SIP server (SIP-Supported- User-Data-Type AVP in the SAR message) and the local policy. Garcia-Martin, et al. Expires March 25, 2006 [Page 32] Internet-Draft Diameter SIP Application September 2005 Additionally, the Diameter server MUST set the Result-Code AVP value to DIAMETER_SUCCESS in the Diameter SAA message. The Diameter server considers the SIP AOR authenticated and registered. o If the SIP-Server-Assignment-Type AVP value in the Diameter SAR message is set to UNREGISTERED_USER then the Diameter server MUST store the SIP server address included in the SIP-Server-URI AVP value. The Diameter server will return the SIP server address in Diameter Location-Info-Answer (LIA) messages. If the SIP-User- Data-Already-Available AVP value is set to USER_DATA_NOT_AVAILABLE, then the Diameter server SHOULD include one or more user profile data associated with the SIP or SIPS URI (SIP-AOR AVP) and associated identities in the SIP-User-Data AVP value of the Diameter SAA message. On selecting the type of user data, the Diameter server SHOULD take into account the supported formats at the SIP server (SIP-Supported-User-Data-Type AVP in the SAR message) and the local policy. The Diameter server MUST set the Result-Code AVP value to DIAMETER_SUCCESS. The Diameter server considers the SIP AOR UNREGISTERED, but with a SIP server allocated to trigger and provide services for unregistered users. Note that in case of UNREGISTERED_USER (SIP-Server-Assignment-Type AVP), the Diameter server MUST verify that there is only one SIP- AOR AVP. Otherwise, the Diameter server MUST answer the Diameter SAR message with a Diameter SAA message, it MUST set the Result- Code AVP value to DIAMETER_AVP_OCCURS_TOO_MANY_TIMES and MUST NOT include any SIP-User-Data AVP. If the User-Name AVP was not present in the Diameter SAR message and the SIP-AOR is not known for the Diameter server, the Diameter server MUST NOT include a User-Name AVP in the Diameter SAA message and MUST set the Result-Code AVP value to DIAMETER_ERROR_USER_UNKNOWN. o If the SIP-Server-Assignment-Type AVP value in the Diameter SAR message is set to TIMEOUT_DEREGISTRATION, USER_DEREGISTRATION, DEREGISTRATION_TOO_MUCH_DATA or ADMINISTRATIVE_DEREGISTRATION the Diameter server MUST clear the SIP server address associated with all SIP Addresses of Record indicated in each of the SIP-AOR AVP values included in the Diameter SAR message. The Diameter server considers all of these SIP Addresses of Record as not registered. The Diameter server MUST set the Result-Code AVP value to DIAMETER_SUCCESS in the Diameter SAA message. o If the SIP-Server-Assignment-Type AVP value in the Diameter SAR message is set to TIMEOUT_DEREGISTRATION_STORE_SERVER_NAME or USER_DEREGISTRATION_STORE_SERVER_NAME the Diameter server MAY keep the SIP server address associated with the SIP Addresses of Record included in the SIP-AOR AVP values of the Diameter SAR message, even though the SIP Addresses of Record will become unregistered. This feature allows a SIP server to request the Diameter server to remain as an assigned SIP server for those SIP Addresses of Record Garcia-Martin, et al. Expires March 25, 2006 [Page 33] Internet-Draft Diameter SIP Application September 2005 (SIP-AOR AVP values), and avoid SIP server assignment. The Diameter server MUST consider all these SIP Addresses of Record as not registered. If the Diameter server honors the request of the Diameter client (SIP server) to remain as an allocated SIP server, then the Diameter server MUST keep the SIP server assigned to those SIP Addresses of Record and MUST set the Result-Code AVP value to DIAMETER_SUCCESS in the Diameter SAA message. Otherwise, when the Diameter server does not honor the request of the Diameter client (SIP server) to remain as an allocated SIP server, the Diameter server MUST clear the SIP server name assigned to those SIP Addresses of Record and it MUST set the Result-Code AVP value to DIAMETER_SUCCESS_SERVER_NAME_NOT_STORED in the Diameter SAA message. o If the SIP-Server-Assignment-Type AVP value in the Diameter SAR message is set to NO_ASSIGNMENT, the Diameter server SHOULD first verify that the SIP-Server-URI AVP value in the Diameter SAR message is the same URI as the one assigned to the SIP-AOR AVP value. If they differ, then the Diameter server MUST set the Result-Code AVP value to DIAMETER_UNABLE_TO_COMPLY in the Diameter SAA message. Otherwise, if the SIP-User-Data-Already-Available AVP value is set to USER_DATA_NOT_AVAILABLE, then the Diameter server SHOULD include the user profile data with the SIP or SIPS URI (SIP-AOR AVP) and all other SIP identities associated with that AVP in the SIP-User-Data AVP value of the Diameter SAA message. On selecting the type of user data, the Diameter server SHOULD take into account the supported formats at the SIP server (SIP-Supported-User-Data-Type AVP in the SAR message) and the local policy. o If the SIP-Server-Assignment-Type AVP value in the Diameter SAR message is set to AUTHENTICATION_FAILURE or AUTHENTICATION_TIMEOUT, the Diameter server MUST verify that there is exactly one SIP-AOR AVP in the Diameter SAR message. If the number of occurrences of the SIP-AOR AVP is not exactly one, the Diameter server MUST set the Result-Code AVP value to DIAMETER_AVP_OCCURS_TOO_MANY_TIMES in the Diameter SAA message, and SHOULD not take further actions. If there is exactly one SIP- AOR AVP in the Diameter SAR message, the Diameter server MUST clear the address of the SIP server assigned to the SIP Address of Record, and the Diameter server MUST set the Result-Code AVP value to DIAMETER_SUCCESS in the Diameter SAA message. The Diameter server MUST consider the SIP AOR as not registered. Garcia-Martin, et al. Expires March 25, 2006 [Page 34] Internet-Draft Diameter SIP Application September 2005 Message Format ::= < Diameter Header: bbb, PXY > < Session-Id > { Auth-Application-Id } { Result-Code } { Auth-Session-State } { Origin-Host } { Origin-Realm } * [ SIP-User-Data ] [ SIP-Accounting-Information ] * [ SIP-Supported-User-Data-Type ] [ User-Name ] [ Auth-Grace-Period ] [ Authorization-Lifetime ] * [ Redirect-Host ] [ Redirect-Host-Usage ] [ Redirect-Max-Cache-Time ] * [ Proxy-Info ] * [ Route-Record ] * [ AVP ] [Note to IANA and the RFC editor: replace bbb with the actual value allocated to this command] 7.5. Location-Info-Request (LIR) Command The Location-Info-Request (LIR) is indicated by the Command-Code set to ccc [Note to IANA and the RFC editor: replace ccc with the actual value allocated to this command] and the Command Flags' 'R' bit set. The Diameter client in a SIP server sends this command to the Diameter server to request routing information, e.g., the URI of the SIP server assigned to a particular user. The user is identified by the SIP-AOR AVP value. Message Format ::= < Diameter Header: ccc, REQ, PXY > < Session-Id > { Auth-Application-Id } { Auth-Session-State } { Origin-Host } { Origin-Realm } { Destination-Realm } { SIP-AOR } [ Destination-Host ] * [ Proxy-Info ] * [ Route-Record ] * [ AVP ] Garcia-Martin, et al. Expires March 25, 2006 [Page 35] Internet-Draft Diameter SIP Application September 2005 [Note to IANA and the RFC editor: replace ccc with the actual value allocated to this command] 7.6. Location-Info-Answer (LIA) Command The Location-Info-Answer (LIA) is indicated by the Command-Code set to ccc [Note to IANA and the RFC editor: replace ccc with the actual value allocated to this command] and the Command Flags' 'R' bit cleared. The Diameter server sends this command in response to a previously received Diameter Location-Info-Request (LIR) command. In addition to the values already defined in RFC 3588 [RFC3588], the Result-Code AVP may contain one of the values defined in Section 9.1. When the Diameter server finds an error in processing the Diameter LIR message, the Diameter server MUST stop the process of the message and answer with a Diameter LIA message that includes the appropriate error code in the Result-Code AVP value. When there is no error, the Diameter server MUST set the Result-Code AVP value to DIAMETER_SUCCESS in the Diameter LIA message. One of the errors that the Diameter server may find is that the SIP- AOR AVP value is not a valid user in the realm. In such cases, the Diameter server MUST set the Result-Code AVP value to DIAMETER_ERROR_USER_UNKNOWN and return it in a Diameter LIA message. If the Diameter server cannot process the Diameter LIR command, e.g., due to a database error, the Diameter server MUST set the Result-Code AVP value to DIAMETER_UNABLE_TO_COMPLY and return it in a Diameter LIA message. The Diameter server MUST NOT include any SIP-Server-URI or SIP-Server-Capabilities AVP in the Diameter LIA message. The Diameter server can or cannot be aware of a SIP server assigned to the user contained in the SIP-AOR AVP value in the Diameter LIR message. If the Diameter server is aware of a SIP server allocated to that particular user, the Diameter server MUST include the URI of such SIP server in the SIP-Server-URI AVP and return it in a Diameter LIA message. This is typically the situation when the user is either registered, or unregistered but there is a SIP server still assigned to the user. When the Diameter server is not aware of a SIP server allocated to the user, typically the case when the user unregistered, the Result- Code AVP value in the Diameter LIA message depends on whether the Diameter server is aware that the user has services defined for unregistered users or not: Garcia-Martin, et al. Expires March 25, 2006 [Page 36] Internet-Draft Diameter SIP Application September 2005 o Those users who have services defined for unregistered users may require the allocation of a SIP server to trigger and perhaps execute those services. Therefore, when the Diameter server is not aware of an assigned SIP server, but the user has services defined for unregistered users, the Diameter server MUST set the Result-Code AVP value to DIAMETER_UNREGISTERED_SERVICE and return it in a Diameter LIA message. The Diameter server MAY also include a SIP-Server-Capabilities AVP to facilitate the SIP server (Diameter client) with the selection of an appropriate SIP server with the required capabilities. Absence of the SIP-Server- Capabilities AVP will indicate to the SIP server (Diameter client) that any SIP server is suitable to be allocated for the user. o Those users who do not have service defined for unregistered users do not require further processing. The Diameter server MUST set the Result-Code AVP value to DIAMETER_ERROR_IDENTITY_NOT_REGISTERED and return it to the Diameter client in a Diameter LIA message. The SIP server (Diameter client) may return the appropriate SIP response (e.g., 480 (Temporarily unavailable)) to the original SIP request. Message Format ::= < Diameter Header: ccc, PXY > < Session-Id > { Auth-Application-Id } { Result-Code } { Auth-Session-State } { Origin-Host } { Origin-Realm } [ SIP-Server-URI ] [ SIP-Server-Capabilities ] [ Auth-Grace-Period ] [ Authorization-Lifetime ] * [ Redirect-Host ] [ Redirect-Host-Usage ] [ Redirect-Max-Cache-Time ] * [ Proxy-Info ] * [ Route-Record ] * [ AVP ] [Note to IANA and the RFC editor: replace ccc with the actual value allocated to this command] 7.7. Multimedia-Auth-Request (MAR) Command The Multimedia-Auth-Request (MAR) command is indicated by the Command-Code set to ddd [Note to IANA and the RFC editor: replace ddd with the actual value allocated to this command] and the Command Flags' 'R' bit set. The Diameter client in a SIP server sends this Garcia-Martin, et al. Expires March 25, 2006 [Page 37] Internet-Draft Diameter SIP Application September 2005 command to the Diameter server to request the Diameter server to authenticate and authorize a user attempt to use some SIP service (in this context, SIP service can be something as simple as a SIP subscription or using the proxy services for a SIP request). Unlike the Diameter SAR command, MAR does not store any state in the Diameter server. The MAR command also registers the SIP server's own URI to the Diameter server, so that future LIR/LIA messages can return this URI. The SIP-Method AVP MUST include the SIP method name of the SIP request that triggered this Diameter MAR message. The Diameter server can use this AVP to authorize some SIP requests depending on the method. The Diameter MAR message MUST include a SIP-AOR AVP. The SIP-AOR AVP indicates the target of the SIP request. The value of the AVP is extracted from different places in SIP request, depending on the semantics of the SIP request. For SIP REGISTER messages the SIP-AOR AVP value indicates the intended public user identity under registration, and it is the SIP or SIPS URI populated in the To header field value (addr-spec, according to the SIP ABNF) of the SIP REGISTER request. For other types of SIP requests, such as INVITE, SUBSCRIBE, MESSAGE, etc., the SIP-AOR AVP value indicates the intended destination of the request. This is typically populated in the Request-URI of the SIP request. It is the Diameter client responsibility to extract the SIP-AOR AVP value from the proper SIP header field. Extensions to SIP (new SIP methods or new semantics) may require to extract the SIP-AOR from other parts of the request. If the SIP request includes some sort of authentication information, the Diameter client MUST include the user name, extracted from the authentication information of the SIP request, in the User-Name AVP value. Garcia-Martin, et al. Expires March 25, 2006 [Page 38] Internet-Draft Diameter SIP Application September 2005 Message Format ::= < Diameter Header: ddd, REQ, PXY > < Session-Id > { Auth-Application-Id } { Auth-Session-State } { Origin-Host } { Origin-Realm } { Destination-Realm } { SIP-AOR } { SIP-Method } [ Destination-Host ] [ User-Name ] [ SIP-Server-URI ] [ SIP-Number-Auth-Items ] [ SIP-Auth-Data-Item ] * [ Proxy-Info ] * [ Route-Record ] * [ AVP ] [Note to IANA and the RFC editor: replace ddd with the actual value allocated to this command] 7.8. Multimedia-Auth-Answer (MAA) Command The Multimedia-Auth-Answer (MAA) is indicated by the Command-Code set to ddd [Note to IANA and the RFC editor: replace ddd with the actual value allocated to this command] and the Command Flags' 'R' bit cleared. The Diameter server sends this command in response to a previously received Diameter Multimedia-Auth-Request (MAR) command. In addition to the values already defined in RFC 3588 [RFC3588], the Result-Code AVP may contain one of the values defined in Section 9.1. If the Diameter server requires a User-Name AVP value to process the Diameter MAR request, but the Diameter MAR message did not contain a User-Name AVP value, the Diameter server MUST set the Result-Code AVP value to DIAMETER_USER_NAME_REQUIRED (see Section 9.1.2) and return it in a Diameter MAA message. The Diameter server MAY include a SIP- Number-Auth-Items AVP and one or more SIP-Auth-Data-Item AVPs with authentication information (e.g., a challenge). Upon reception of this Diameter MAA message with the Result-Code AVP value set to DIAMETER_USER_NAME_REQUIRED, the SIP server will typically request authentication by generating a SIP 401 (Unauthorized) or SIP 407 (Proxy Authentication Required) response back to the originator. If the User-Name AVP is present in the Diameter MAR message, the Diameter server MUST verify the existence of the user in the realm, i.e., the User-Name AVP value is a valid user within that realm. If Garcia-Martin, et al. Expires March 25, 2006 [Page 39] Internet-Draft Diameter SIP Application September 2005 the Diameter server does not recognize the user name received in the User-Name AVP, the Diameter server MUST build a Diameter Multimedia- Auth-Answer (MAA) message and MUST set the Result-Code AVP to DIAMETER_ERROR_USER_UNKNOWN. If the SIP-Methods AVP value of the Diameter MAR message is set to REGISTER and a User-Name AVP is present, then the Diameter server MUST authorize that User-Name AVP value is able to use the URI included in the SIP-AOR AVP. If this authorization fails, the Diameter server must set the Result-Code AVP to DIAMETER_ERROR_IDENTITIES_DONT_MATCH and send it in a Diameter Multimedia-Auth-Answer (MAA) message. Correlation between User-Name and SIP-AOR AVP values is only required for SIP REGISTER request, just to avoid that any user can register a SIP-AOR allocated to another user. In other types of SIP requests (e.g., INVITE), the SIP-AOR will indicate the intended destination of the request, rather than the originator of it. Then Diameter server MUST verify whether the authentication scheme (SIP-Authentication-Scheme AVP value) indicated in the grouped SIP- Auth-Data-Item AVP is supported or not. If that authentication scheme is not supported, then the Diameter server MUST set the Result-Code AVP to DIAMETER_ERROR_AUTH_SCHEME_NOT_SUPPORTED and send it in a Diameter Multimedia-Auth-Answer (MAA) message. If the received Diameter MAR message contains a grouped SIP- Authorization AVP within the grouped SIP-Auth-Data-Item AVP, the Diameter server considers that the authorization information is being requested after a synchronization failure. In this case, the sequence of the SIP-Auth-Data-Item AVPs would take into account the SIP-Authorization AVP value to synchronize the different authentication credentials. The Diameter server MUST set the Result- Code AVP to DIAMETER_SUCCESS. If the SIP-Number-Auth-Items AVP is present in the Diameter MAR message, it will indicate the number of authentication data items that the Diameter client is requesting. It is RECOMMENDED that the Diameter server, when building the Diameter MAA message, includes a number of SIP-Auth-Data-Item AVPs that is a subset of the authentication data items requested by the Diameter client in the SIP-Number-Auth-Items AVP value of the Diameter MAR message. If the SIP-Server-URI AVP is present in the Diameter MAR message, then the Diameter server MUST compare the stored SIP server assigned to the SIP AOR with the SIP-Server-URI AVP value received in the Diameter MAR message. If there is not a match, the Diameter server Garcia-Martin, et al. Expires March 25, 2006 [Page 40] Internet-Draft Diameter SIP Application September 2005 MUST update the stored SIP server assigned to the SIP AOR, and MUST set an "authentication pending" flag for the SIP AOR. If there is a match, the Diameter server shall clear the "authentication pending" flag for the SIP AOR. In any other situation, if there is a success in processing the Diameter MAR command and the Diameter server stored the SIP-Server- URI, the Diameter server MUST set the Result-Code AVP value to DIAMETER_SUCCESS and return it in a Diameter MAA message. If there is a success in processing the Diameter MAR command but the Diameter server does not store the SIP-Server-URI because the AVP was not present in the Diameter MAR command, then the Diameter server MUST set the Result-Code AVP value to either: 1. DIAMETER_SUCCESS_AUTH_SENT_SERVER_NOT_STORED, if the Diameter server is sending authentication credentials to create a challenge. 2. DIAMETER_SUCCESS_SERVER_NAME_NOT_STORED, if the Diameter server successfully authenticated the user and authorized the SIP server to proceed with the SIP request. Otherwise, the Diameter server MUST set the Result-Code AVP value to DIAMETER_UNABLE_TO_COMPLY and it MUST NOT include any SIP-Auth-Data- Item AVP. Message Format ::= < Diameter Header: ddd, PXY > < Session-Id > { Auth-Application-Id } { Result-Code } { Auth-Session-State } { Origin-Host } { Origin-Realm } [ User-Name ] [ SIP-AOR ] [ SIP-Number-Auth-Items ] * [ SIP-Auth-Data-Item ] [ Authorization-Lifetime ] [ Auth-Grace-Period ] * [ Redirect-Host ] [ Redirect-Host-Usage ] [ Redirect-Max-Cache-Time ] * [ Proxy-Info ] * [ Route-Record ] * [ AVP ] [Note to IANA and the RFC editor: replace ddd with the actual value Garcia-Martin, et al. Expires March 25, 2006 [Page 41] Internet-Draft Diameter SIP Application September 2005 allocated to this command] 7.9. Registration-Termination-Request (RTR) Command The Registration-Termination-Request (RTR) command is indicated by the Command-Code set to eee [Note to IANA and the RFC editor: replace eee with the actual value allocated to this command] and the Command Flags' 'R' bit set. The Diameter server sends this command to the Diameter client in a SIP server to indicate the SIP server that one or more SIP AORs have to be de-registered. The command allows an operator to administratively cancel the registration of a user from a centralized Diameter server. The Diameter server has the capability to initiate the de- registration of a user and inform the SIP server by means of the Diameter RTR command. The Diameter server can decide whether only one SIP AOR is going to be deregistered, a list of SIP AORs, or all the SIP AORs allocated to the user. The absence of a SIP-AOR AVP in the Diameter RTR message indicates that all the SIP Addresses of Record allocated to the user identified by the User-Name AVP are being deregistered. The Diameter server MUST include a SIP-Deregistration-Reason AVP value to indicate the reason for the deregistration. Message Format ::= < Diameter Header: eee, REQ, PXY > < Session-Id > { Auth-Application-Id } { Auth-Session-State } { Origin-Host } { Origin-Realm } { Destination-Host } { SIP-Deregistration-Reason } [ Destination-Realm ] [ User-Name ] * [ SIP-AOR ] * [ Proxy-Info ] * [ Route-Record ] * [ AVP ] [Note to IANA and the RFC editor: replace eee with the actual value allocated to this command] 7.10. Registration-Termination-Answer (RTA) Command The Registration-Termination-Answer (RTA) is indicated by the Garcia-Martin, et al. Expires March 25, 2006 [Page 42] Internet-Draft Diameter SIP Application September 2005 Command-Code set to eee [Note to IANA and the RFC editor: replace eee with the actual value allocated to this command] and the Command Flags' 'R' bit cleared. The Diameter client sends this command in response to a previously received Diameter Registration-Termination- Request (RTR) command. In addition to the values already defined in RFC 3588 [RFC3588], the Result-Code AVP may contain one of the values defined in Section 9.1. If the Diameter server requires a User-Name AVP value to process the Diameter RTR request, but the Diameter RTR message did not contain a User-Name AVP value, the Diameter server MUST set the Result-Code AVP value to DIAMETER_USER_NAME_REQUIRED (see Section 9.1.2) and return it in a Diameter RTA message. Upon reception of this Diameter RTA message with the Result-Code AVP value set to DIAMETER_USER_NAME_REQUIRED, the SIP server will typically request authentication by generating a SIP 401 (Unauthorized) or SIP 407 (Proxy Authentication Required) response back to the originator. The SIP server (Diameter client) will apply the administrative deregistration to each of the URIs included in each of the SIP-AOR AVP values, or, if there is no SIP-AOR AVP present in the Diameter RTR request, to all the URIs allocated to the User-Name AVP value. The value of the SIP-Deregistration-Reason AVP in the Diameter RTR command will have an effect on the actions performed at the SIP server (Diameter client): o If the value is set to PERMANENT_TERMINATION, then the user has terminated his/her registration to the realm. The SIP server (Diameter client), if supported through SIP procedures, SHOULD inform the interested parties (e.g., subscribers to the registration event) about the administrative de-registration and SHOULD NOT request a new user registration. The SIP server SHOULD clear the registration state of the de-registered AORs. o If the value is set to NEW_SIP_SERVER_ASSIGNED, the Diameter server informs the SIP server (Diameter client) that a new SIP server has been allocated to the user, due to some reason. The SIP server, if supported through SIP procedures, SHOULD inform the interested parties (e.g., subscribers to the registration event) about the administrative de-registration at this SIP server and SHOULD NOT request a new user registration. The SIP server SHOULD clear the registration state of the de-registered SIP AORs. o If the value is set to SIP_SERVER_CHANGE, the Diameter server informs the SIP server (Diameter client) that a new SIP server has to be allocated to the user, due to e.g. user's capabilities requiring a new SIP server, or not enough resources in the current SIP server. The SIP server, if supported through SIP procedures, Garcia-Martin, et al. Expires March 25, 2006 [Page 43] Internet-Draft Diameter SIP Application September 2005 SHOULD inform the interested parties (e.g., subscribers to the registration event) about the administrative de-registration at this SIP server and SHOULD request a new user registration. The SIP server SHOULD clear the registration state of the de- registered SIP AORs. o If the value is set to REMOVE_SIP_SERVER, the Diameter server informs the SIP server (Diameter client) that the SIP server will no longer be bound in the Diameter server with such user. The SIP server can delete all data related to the user. Message Format ::= < Diameter Header: eee, PXY > < Session-Id > { Auth-Application-Id } { Result-Code } { Auth-Session-State } { Origin-Host } { Origin-Realm } [ Authorization-Lifetime ] [ Auth-Grace-Period ] * [ Redirect-Host ] [ Redirect-Host-Usage ] [ Redirect-Max-Cache-Time ] * [ Proxy-Info ] * [ Route-Record ] * [ AVP ] [Note to IANA and the RFC editor: replace eee with the actual value allocated to this command] 7.11. Push-Profile-Request (PPR) Command The Push-Profile-Request (PPR) command is indicated by the Command- Code set to fff [Note to IANA and the RFC editor: replace fff with the actual value allocated to this command] and the Command Flags' 'R' bit set. The Diameter server sends this command to the Diameter client in a SIP server to update the user profile of an already registered user in that SIP server. This allows an operator to modify the data of a user profile and push it to the SIP server where the user is registered. Each user has a user profile associated with him/her. The profile may change with time, due to, e.g., addition of new services to the user. When the user profile changes, the Diameter server sends a Diameter Push-Profile-Request (PPR) command to the Diameter client in a SIP server, in order to start applying those new services. A PPR command MAY contain a SIP-Accounting-Information AVP that Garcia-Martin, et al. Expires March 25, 2006 [Page 44] Internet-Draft Diameter SIP Application September 2005 updates the addresses of the accounting servers. Changes in the addresses of the accounting servers take effect immediately. The Diameter client SHOULD close any existing accounting session with the existing server and start providing accounting information to the newly acquired accounting server. The Diameter server sends the new user profile in one or more SIP- User-Data AVP value. On selecting the type of user data, the Diameter server SHOULD take into account the supported formats at the SIP server (SIP-Supported-User-Data-Type AVP sent in a previous SAR message) and the local policy. The user to who the profile is applicable is indicated by the User- Name AVP. Garcia-Martin, et al. Expires March 25, 2006 [Page 45] Internet-Draft Diameter SIP Application September 2005 Message Format ::= < Diameter Header: fff, REQ, PXY > < Session-Id > { Auth-Application-Id } { Auth-Session-State } { Origin-Host } { Origin-Realm } { Destination-Realm } * { SIP-User-Data } { User-Name } [ SIP-Accounting-Information ] [ Destination-Host ] [ Authorization-Lifetime ] [ Auth-Grace-Period ] * [ Proxy-Info ] * [ Route-Record ] * [ AVP ] [Note to IANA and the RFC editor: replace fff with the actual value allocated to this command] 7.12. Push-Profile-Answer (PPA) Command The Push-Profile-Answer (PPA) is indicated by the Command-Code set to fff [Note to IANA and the RFC editor: replace fff with the actual value allocated to this command] and the Command Flags' 'R' bit cleared. The Diameter client sends this command in response to a previously received Diameter Push-Profile-Request (PPR) command. In addition to the values already defined in RFC 3588 [RFC3588], the Result-Code AVP may contain one of the values defined in Section 9.1. If there is no error when processing the received Diameter PPR message, the SIP server (Diameter client) MUST download the received user profile from the SIP-User-Data AVP values in the Diameter PPR message and store it associated with the user specified in the User- Name AVP value. If the SIP server does not recognize or does not support some of the data transferred in the SIP-User-Data AVP values, the Diameter client in the SIP server MUST return a Diameter PPA message that includes a Result-Code AVP set to the value DIAMETER_ERROR_NOT_SUPPORTED_USER_DATA. If the SIP server (Diameter client) receives a Diameter PPR message with a User-Name AVP that is unknown, the Diameter client MUST set the Result-Code AVP value to DIAMETER_ERROR_USER_UNKNOWN and MUST return it to the Diameter server in a Diameter PPA message. Garcia-Martin, et al. Expires March 25, 2006 [Page 46] Internet-Draft Diameter SIP Application September 2005 If the SIP server (Diameter client) receives in the SIP-User-Data- Content AVP value (of the grouped SIP-User-Data AVP) more data than it can accept, it MUST set the Result-Code AVP value to DIAMETER_ERROR_TOO_MUCH_DATA and MUST return it to the Diameter server in a Diameter PPA message. The SIP server MUST NOT override the existing user profile with that received in the PPR message. If the Diameter server receives the Result-Code AVP value set to DIAMETER_ERROR_TOO_MUCH_DATA in a Diameter PPA message, it SHOULD force a new re-registration of the user by sending to the Diameter client a Diameter Registration-Termination-Request (RTR) with the SIP-Deregistration-Reason AVP value set to SIP_SERVER_CHANGE. This will force a re-registration of the user, and will trigger a selection of a new SIP server. If the Diameter client is not able to honor the command, for any other reason, it MUST set the Result-Code AVP value to DIAMETER_UNABLE_TO_COMPLY and it MUST return it in a Diameter PPA message. Message Format ::= < Diameter Header: fff, PXY > < Session-Id > { Auth-Application-Id } { Result-Code } { Auth-Session-State } { Origin-Host } { Origin-Realm } * [ Redirect-Host ] [ Redirect-Host-Usage ] [ Redirect-Max-Cache-Time ] * [ Proxy-Info ] * [ Route-Record ] * [ AVP ] [Note to IANA and the RFC editor: replace fff with the actual value allocated to this command] 8. Diameter SIP Application AVPs This section defines new AVPs used in this Diameter SIP application. Applications compliant to this specification MUST implement these AVPs. Table 2 lists the new AVPs defined in this Diameter SIP application. Garcia-Martin, et al. Expires March 25, 2006 [Page 47] Internet-Draft Diameter SIP Application September 2005 The following abbreviations are used in the Data-Type column: * DURI: DiameterURI * E: Enumerated * G: Grouped * OS: OctetString * UTF8S: UTF8String * U32: Unsigned32 +---------------------------------+------+----------------+---------+ | AVP Name | AVP | Reference | Data-Ty | | | Code | | pe | +---------------------------------+------+----------------+---------+ | SIP-Accounting-Information | xx01 | Section 8.1 | G | | SIP-Accounting-Server-URI | xx02 | Section 8.1.1 | DURI | | SIP-Credit-Control-Server-URI | xx03 | Section 8.1.2 | DURI | | SIP-Server-URI | xx04 | Section 8.2 | UTF8S | | SIP-Server-Capabilities | xx05 | Section 8.3 | G | | SIP-Mandatory-Capability | xx06 | Section 8.3.1 | U32 | | SIP-Optional-Capability | xx07 | Section 8.3.2 | U32 | | SIP-Server-Assignment-Type | xx08 | Section 8.4 | E | | SIP-Auth-Data-Item | xx09 | Section 8.5 | G | | SIP-Authentication-Scheme | xx10 | Section 8.5.1 | E | | SIP-Item-Number | xx11 | Section 8.5.2 | U32 | | SIP-Authenticate | xx12 | Section 8.5.3 | G | | SIP-Authorization | xx13 | Section 8.5.4 | G | | SIP-Authentication-Info | xx14 | Section 8.5.5 | G | | SIP-Number-Auth-Items | xx15 | Section 8.6 | U32 | | SIP-Deregistration-Reason | xx16 | Section 8.7 | G | | SIP-Reason-Code | xx17 | Section 8.7.1 | E | | SIP-Reason-Info | xx18 | Section 8.7.2 | UTF8S | | SIP-Visited-Network-Id | xx19 | Section 8.9 | UTF8S | | SIP-User-Authorization-Type | xx20 | Section 8.10 | E | | SIP-Supported-User-Data-Type | xx21 | Section 8.11 | UTF8S | | SIP-User-Data | xx22 | Section 8.12 | G | | SIP-User-Data-Type | xx23 | Section 8.12.1 | UTF8S | | SIP-User-Data-Contents | xx24 | Section 8.12.2 | OS | | SIP-User-Data-Already-Available | xx25 | Section 8.13 | E | | SIP-Method | xx26 | Section 8.14 | UTF8S | +---------------------------------+------+----------------+---------+ Table 2: Defined AVPs [Note to IANA and the RFC editor: replace xx01, xx02, xx03, and so on with the actual values allocated to these AVPs.] Table 3 expands the table of AVPs included in Section 4.5 of RFC 3588 [RFC3588]. The table indicates the Diameter AVPs defined in this Garcia-Martin, et al. Expires March 25, 2006 [Page 48] Internet-Draft Diameter SIP Application September 2005 Diameter SIP Application, their possible flag values, and whether the AVP may be encrypted. The acronyms 'M', 'P', and 'V' refer to AVP flags whose semantics are described in RFC 3588 [RFC3588]. The value of the 'Encr' column is also described in RFC 3588 [RFC3588]. +----------------------------------+------+-----+-----+------+------+ | AVP Name | MUST | MAY | SHD | MUST | Encr | | | | | NOT | NOT | | +----------------------------------+------+-----+-----+------+------+ | SIP-Accounting-Information | M | P | | V | N | | SIP-Accounting-Server-URI | M | P | | V | N | | SIP-Credit-Control-Server-URI | M | P | | V | N | | SIP-Server-URI | M | P | | V | N | | SIP-Server-Capabilities | M | P | | V | N | | SIP-Mandatory-Capability | M | P | | V | N | | SIP-Optional-Capability | M | P | | V | N | | SIP-Server-Assignment-Type | M | P | | V | N | | SIP-Auth-Data-Item | M | P | | V | N | | SIP-Authentication-Scheme | M | P | | V | N | | SIP-Item-Number | M | P | | V | N | | SIP-Authenticate | M | P | | V | N | | SIP-Authorization | M | P | | V | N | | SIP-Authentication-Info | M | P | | V | N | | SIP-Number-Auth-Items | M | P | | V | N | | SIP-Deregistration-Reason | M | P | | V | N | | SIP-Reason-Code | M | P | | V | N | | SIP-Reason-Info | M | P | | V | N | | SIP-Visited-Network-Id | M | P | | V | N | | SIP-User-Authorization-Type | M | P | | V | N | | SIP-Supported-User-Data-Type | M | P | | V | N | | SIP-User-Data | M | P | | V | N | | SIP-User-Data-Type | M | P | | V | N | | SIP-User-Data-Contents | M | P | | V | N | | SIP-User-Data-Already-Available | M | P | | V | N | | SIP-Method | M | P | | V | N | +----------------------------------+------+-----+-----+------+------+ Table 3: Summary of the new AVPs flags 8.1. SIP-Accounting-Information AVP The SIP-Accounting-Information (AVP code xx01) [Note to IANA and the RFC editor: replace xx01 with the actual value allocated to this AVP] is of type Grouped, and contains the Diameter addresses of those nodes that are able to collect accounting information. The Grouped Data field has the following ABNF grammar: Garcia-Martin, et al. Expires March 25, 2006 [Page 49] Internet-Draft Diameter SIP Application September 2005 SIP-Accounting-Information :: = < AVP Header: xx01 > * [ SIP-Accounting-Server-URI ] * [ SIP-Credit-Control-Server-URI ] * [ AVP] [Note to IANA and the RFC editor: replace xx01 with the actual value allocated to this AVP] 8.1.1. SIP-Accounting-Server-URI AVP The SIP-Accounting-Server-URI AVP (AVP Code xx02) [Note to IANA and the RFC editor: replace xx02 with the actual value allocated to this AVP] is of type DiameterURI. This AVP contains the address of a Diameter server that is able to receive SIP session related accounting information. 8.1.2. SIP-Credit-Control-Server-URI AVP The SIP-Credit-Control-Server-URI AVP (AVP Code xx03) [Note to IANA and the RFC editor: replace xx03 with the actual value allocated to this AVP] is of type DiameterURI. This AVP contains the address of the a Diameter server that is able to authorize real-time credit control usage. The Diameter Credit Control Application [RFC4006] may be used for this purpose. 8.2. SIP-Server-URI AVP The SIP-Server-URI AVP (AVP Code xx04) [Note to IANA and the RFC editor: replace xx04 with the actual value allocated to this AVP] is of type UTF8String. This AVP contains a SIP or SIPS URI (as defined in RFC 3261 [RFC3261]) that identifies a SIP server. 8.3. SIP-Server-Capabilities AVP The SIP-Server-Capabilities AVP (AVP Code xx05) [Note to IANA and the RFC editor: replace xx05 with the actual value allocated to this AVP] is of type Grouped. The Diameter indicates in this AVP the requirements for a particular SIP capability, so that the Diameter client (SIP server) is able to select another appropriate SIP server to serve the user. SIP-Server-Capabilities ::= < AVP Header: xx05 > * [ SIP-Mandatory-Capability ] * [ SIP-Optional-Capability ] * [ SIP-Server-URI ] * [ AVP ] [Note to IANA and the RFC editor: replace xx05 with the actual value Garcia-Martin, et al. Expires March 25, 2006 [Page 50] Internet-Draft Diameter SIP Application September 2005 allocated to this AVP] 8.3.1. SIP-Mandatory-Capability AVP The SIP-Mandatory-Capability AVP (AVP Code xx06) [Note to IANA and the RFC editor: replace xx06 with the actual value allocated to this AVP] is of type Unsigned32. The value represents a certain capability (or set of capabilities) that the SIP server to be allocated to the user has to fulfil. The semantics of the different values are not standardized, as it is a matter of the administrative network to allocate its own semantics within its own network. Each value has to represent a single capability within the administrative network. 8.3.2. SIP-Optional-Capability AVP The SIP-Optional-Capability AVP (AVP Code xx07) [Note to IANA and the RFC editor: replace xx07 with the actual value allocated to this AVP] is of type Unsigned32. The value represents a certain capability (or set of capabilities) that the SIP server to be allocated may, optionally, fulfil. The semantics of the different values are not standardized, as it is a matter of the administrative network to allocate its own semantics within its own network. Each value has to represent a single capability within the administrative network. 8.4. SIP-Server-Assignment-Type AVP The SIP-Server-Assignment-Type AVP (AVP code xx08) [Note to IANA and the RFC editor: replace xx08 with the actual value allocated to this AVP] is of type Enumerated, and indicates the type of server update being performed in a Diameter Server-Assignment-Request (SAR) operation. The following values are defined: o NO_ASSIGNMENT (0) The Diameter client uses this value to request the user profile of a SIP AOR, without affecting the registration state of such identity. o REGISTRATION (1) First SIP registration of a SIP AOR. o RE_REGISTRATION (2) Subsequent SIP registration of a SIP AOR. o UNREGISTERED_USER (3) The SIP server has received a SIP request (e.g., SIP INVITE) addressed for a SIP AOR that is not registered. Garcia-Martin, et al. Expires March 25, 2006 [Page 51] Internet-Draft Diameter SIP Application September 2005 o TIMEOUT_DEREGISTRATION (4) The SIP registration timer of an identity has expired. o USER_DEREGISTRATION (5) The SIP server has received a request to de-register a SIP AOR. o TIMEOUT_DEREGISTRATION_STORE_SERVER_NAME (6) The SIP registration timer of an identity has expired. The SIP server keeps the user data stored and requests the Diameter server to store the SIP server address. o USER_DEREGISTRATION_STORE_SERVER_NAME (7) The SIP server has received a user initiated de-registration request. The SIP server keeps the user data stored and requests the Diameter server to store the SIP server address. o ADMINISTRATIVE_DEREGISTRATION (8) The SIP server, due to administrative reasons, has de-registered a SIP AOR. o AUTHENTICATION_FAILURE (9) The authentication of a user has failed. o AUTHENTICATION_TIMEOUT (10) The authentication timer has expired. o DEREGISTRATION_TOO_MUCH_DATA (11) The SIP server has requested user profile information from the Diameter server and has received a volume of data higher than it can accept. 8.5. SIP-Auth-Data-Item AVP The SIP-Auth-Data-Item (AVP code xx09) [Note to IANA and the RFC editor: replace xx09 with the actual value allocated to this AVP] is of type Grouped and contains the authentication and/or authorization information pertaining to a user. When the Diameter server uses the grouped SIP-Auth-Data-Item AVP to include a SIP-Authenticate AVP, the Diameter server MUST send a maximum of one authentication data item (e.g., in case the SIP request contained several credentials). Section 10 contains a detailed discussion and normative text of the case when a SIP request contains several credentials. SIP-Auth-Data-Item :: = < AVP Header: xx09 > { SIP-Authentication-Scheme } [ SIP-Item-Number ] [ SIP-Authenticate ] [ SIP-Authorization ] [ SIP-Authentication-Info ] * [ AVP ] [Note to IANA and the RFC editor: replace xx09 with the actual value allocated to this AVP] Garcia-Martin, et al. Expires March 25, 2006 [Page 52] Internet-Draft Diameter SIP Application September 2005 8.5.1. SIP-Authentication-Scheme AVP The SIP-Authentication-Scheme AVP (AVP code xx10) [Note to IANA and the RFC editor: replace xx10 with the actual value allocated to this AVP] is of type Enumerated and indicates the authentication scheme used in the authentication of SIP services. RFC 2617 identifies this value as an "auth-scheme" (see section 1.2 of RFC 2617 [RFC2617]). The only currently defined value is: o DIGEST (0) to indicate HTTP Digest authentication as specified in RFC 2617 [RFC2617] Section 3.2.1. Derivative work is also considered Digest authentication scheme, as long as the "auth- scheme" is identified as Digest in the SIP headers carrying the HTTP authentication. This includes, e.g., the HTTP Digest authentication using AKA [RFC3310]. Each HTTP Digest directive (parameter) is transported in a corresponding AVP, whose name follows the pattern Digest-*. The Digest-* AVPs are RADIUS attributes imported from the RADIUS Extension for Digest Authentication [I-D.ietf-radext-digest-auth] namespace, allowing a smooth transition between RADIUS and Diameter applications supporting SIP. The Diameter SIP application goes a step further by grouping the Digest-* AVPs into the SIP-Authenticate, SIP-Authorization, and SIP-Authentication-Info grouped AVPs, that correspond to the SIP WWW-Authenticate/Proxy-Authenticate, Authorization/Proxy-authorization and Authentication-Info headers fields, respectively. NOTE: Due to the fact that HTTP Digest authentication [RFC2617] is the only mandatory authentication mechanism in SIP, this memo only provides support for HTTP Digest authentication and derivative work such as HTTP Digest authentication using AKA [RFC3310]. Extensions to this memo can register new values and new AVPs to provide support for other authentication schemes. NOTE: Although RFC 2617 [RFC2617] defines the Basic and Digest schemes for authenticating HTTP requests, RFC 3261 [RFC3261] only imports HTTP Digest as a mechanism to provide authentication in SIP. 8.5.2. SIP-Item-Number AVP The SIP-Item-Number (AVP code xx11) [Note to IANA and the RFC editor: replace xx11 with the actual value allocated to this AVP] is of type Unsigned32, and is included in a SIP-Auth-Data-Item grouped AVP in circumstances where there are multiple occurrences of SIP-Auth-Data- Item AVPs and the order of processing is relevant. The AVP indicates the order in which the Grouped SIP-Auth-Data-Item should be Garcia-Martin, et al. Expires March 25, 2006 [Page 53] Internet-Draft Diameter SIP Application September 2005 processed. Lower values of the SIP-Item-Number AVP indicate that the whole SIP-Auth-Data-Item SHOULD be processed before other SIP-Auth- Data-Item AVP that contain a higher value number in the SIP-Item- Number AVP. 8.5.3. SIP-Authenticate AVP The SIP-Authenticate AVP (AVP code xx12) [Note to IANA and the RFC editor: replace xx12 with the actual value allocated to this AVP] is of type Grouped and contains a reconstruction of either the SIP WWW- Authenticate or Proxy-Authenticate header fields specified in RFC 2617 [RFC2617] for the HTTP Digest authentication scheme. Additionally, the AVP may include a Digest-HA1 AVP that contains H(A1) (as defined in RFC 2617 [RFC2617]). H(A1) allows the Diameter client to create an expected response and compare it with the Digest response received from the SIP UA. SIP-Authenticate ::= < AVP Header: xx12 > { Digest-Realm } { Digest-Nonce } [ Digest-Domain ] [ Digest-Opaque ] [ Digest-Stale ] [ Digest-Algorithm ] [ Digest-QoP ] [ Digest-HA1] * [ Digest-Auth-Param ] * [ AVP ] [Note to IANA and the RFC editor: replace xx12 with the actual value allocated to this AVP] 8.5.4. SIP-Authorization AVP The SIP-Authorization AVP (AVP code xx13) [Note to IANA and the RFC editor: replace xx13 with the actual value allocated to this AVP] is of type Grouped and contains a reconstruction of either the SIP Authorization or Proxy-Authorization header fields specified in RFC 2617 [RFC2617] for the HTTP Digest authentication scheme. Garcia-Martin, et al. Expires March 25, 2006 [Page 54] Internet-Draft Diameter SIP Application September 2005 SIP-Authorization ::= < AVP Header: xx13 > { Digest-Username } { Digest-Realm } { Digest-Nonce } { Digest-URI } { Digest-Response } [ Digest-Algorithm ] [ Digest-CNonce ] [ Digest-Opaque ] [ Digest-QoP ] [ Digest-Nonce-Count ] [ Digest-Method] [ Digest-Entity-Body-Hash ] * [ Digest-Auth-Param ] * [ AVP ] [Note to IANA and the RFC editor: replace xx13 with the actual value allocated to this AVP] 8.5.5. SIP-Authentication-Info AVP The SIP-Authentication-Info AVP (AVP Code xx14) [Note to IANA and the RFC editor: replace xx14 with the actual value allocated to this AVP] is of type Grouped and contains a reconstruction of the SIP Authentication-Info header specified in RFC 2617 [RFC2617] for the HTTP Digest authentication scheme. SIP-Authentication-Info ::= < AVP Header: xx14 > { Digest-Nextnonce } [ Digest-QoP ] [ Digest-Response-Auth ] [ Digest-CNonce ] [ Digest-Nonce-Count ] * [ AVP ] [Note to IANA and the RFC editor: replace xx14 with the actual value allocated to this AVP] Note that, in some cases, the Digest-Response-Auth AVP cannot be calculated at the Diameter server, but has to be calculated at the Diameter client (SIP server). For example, if the value of the quality of protection (qop) parameter in Digest is set to "auth-int", then the response-digest (rspauth parameter value in Digest) is calculated with the hash of the body of the SIP response, which is not available at the Diameter server. In this case, the Diameter client (SIP server) must calculate the response-digest once the body of the SIP response will be calculated. Garcia-Martin, et al. Expires March 25, 2006 [Page 55] Internet-Draft Diameter SIP Application September 2005 Therefore, a value of "auth-int" in the Digest-QoP AVP of the SIP- Authentication-Info AVP indicates that the Diameter client (SIP server) MUST compute the Digest "rspauth" parameter value at the Diameter client (SIP server). 8.5.6. Digest AVPs The following AVPs are RADIUS attributes defined in the RADIUS Extension for Digest Authentication [I-D.ietf-radext-digest-auth] and imported by this specification: Digest-AKA-Auts, Digest-Algorithm, Digest-Auth-Param, Digest-CNonce, Digest-Domain, Digest-Entity-Body- Hash, Digest-HA1, Digest-Method, Digest-Nextnonce, Digest-Nonce, Digest-Nonce-Count, Digest-Opaque, Digest-QoP, Digest-Realm, Digest- Response, Digest-Response-Auth, Digest-URI, Digest-Username, and Digest-Stale. 8.5.6.1. Considerations about Digest-HA1 AVP The Digest-HA1 AVP contains the value, pre-calculated at the Diameter server, of H(A1) as defined in RFC 2617 [RFC2617]. The Diameter client can use H(A1) to calculate the expected Digest response, according to this challenge. If the SIP UA is in possession of the credentials, the calculated expected response and the response sent from the SIP UA will match. The Diameter server MAY include this AVP to enable and assist the SIP server in authenticating the SIP UA. This scenario is applicable when the Diameter server is configured to use the MD5 Message-Digest algorithm in the HTTP Digest authentication. If the Diameter server is configured to use a session MD5 (MD5-sess) algorithm, then the Diameter server requires the client nonce to compute the H(A1) before sending it to the Diameter client, and the client nonce might not be available at the time the computation of H(A1) is done. Therefore, it is RECOMMENDED to configure the Diameter server to use MD5 as the algorithm in HTTP Digest, if the final authentication is delegated to the Diameter client. It is up to the Diameter server to include a Digest-HA1 AVP. The Diameter server calculates the Digest H(A1) with the username, password, realm, (and nonce and cnonce if applicable), as inputs, and places the result in the Digest-HA1 AVP value. For more details of the A1 computation see RFC 2617 [RFC2617] Section 3.2.2.2. The Diameter client can calculate the Digest expected response with H(A1) as input, as described in RFC 2617 [RFC2617] Section 3.2.2. Section 10 provide further normative details about the usage of the Digest-HA1 AVP. Garcia-Martin, et al. Expires March 25, 2006 [Page 56] Internet-Draft Diameter SIP Application September 2005 8.5.6.2. Considerations about Digest-Entity-Body-Hash AVP The Digest-Entity-Body-Hash AVP contains a hash of the entity body contained in the SIP message. This hash is required by HTTP Digest with quality of protection set to "auth-int". Diameter clients MUST use this AVP to transport the hash of the entity body when HTTP Digest is the authentication mechanism and the Diameter server requires to verify the integrity of the entity body (e.g., qop parameter set to "auth-int"). The clarifications described in Section 22.4 of RFC 3261 [RFC3261] about the hash of empty entity bodies apply to the Digest-Entity- Body-Hash AVP. 8.5.6.3. Considerations about Digest-Auth-Param AVP The Digest-Auth-Param AVP is the mechanism whereby the Diameter client and Diameter server can exchange possible extension parameters contained in Digest headers that are not understood by the Diameter client and for which there are no corresponding stand-alone AVPs. Unlike the previously listed Digest-* AVPs, the Digest-Auth-Param contains not only the value, but also the parameter name, since the parameter name is unknown to the Diameter client. The Diameter node MUST insert one Digest parameter/value combination per AVP value. If the Digest header contains several unknown parameters, then the Diameter implementation MUST repeat this AVP and each instance MUST contain one different unknown Digest parameter/value combination. This AVP corresponds to the "auth-param" parameter defined in Section 3.2.1 of RFC 2617 [RFC2617]. Example: Assume that the Diameter server wants the SIP server to send a "foo" parameter with the value set to "bar", so that the SIP server sends that combination in a SIP WWW-Authenticate header field. The Diameter server builds a grouped SIP-Authenticate AVP that contains a Digest-Auth-Param whose value is set to foo="bar". Then the SIP server creates the WWW-Authenticate header field with all the digest parameters (received in Digest-* AVPs) and adds the foo="bar" parameter to that header field. 8.6. SIP-Number-Auth-Items AVP The SIP-Number-Auth-Items AVP (AVP Code xx15) [Note to IANA and the RFC editor: replace xx15 with the actual value allocated to this AVP]is of type Unsigned32 and indicates the number of authentication and/or authorization credentials that the Diameter server included in a Diameter message. When the AVP is present in a request, it indicates the number of SIP- Garcia-Martin, et al. Expires March 25, 2006 [Page 57] Internet-Draft Diameter SIP Application September 2005 Auth-Data-Items the Diameter client is requesting. This can be used, for instance, when the SIP server is requesting several pre- calculated authentication credentials. In the answer message, the SIP-Number-Auth-Items AVP indicates the actual number of items that the Diameter server included. 8.7. SIP-Deregistration-Reason AVP The SIP-Deregistration-Reason AVP (AVP Code xx16) [Note to IANA and the RFC editor: replace xx16 with the actual value allocated to this AVP] is of type Grouped, and indicates the reason for a deregistration operation. SIP-Deregistration-Reason ::= < AVP Header: xx16 > { SIP-Reason-Code } [ SIP-Reason-Info ] * [ AVP ] [Note to IANA and the RFC editor: replace xx16 with the actual value allocated to this AVP] 8.7.1. SIP-Reason-Code AVP The SIP-Reason-Code AVP (AVP code xx17) [Note to IANA and the RFC editor: replace xx17 with the actual value allocated to this AVP] is of type Enumerated, and defines the reason for the network initiated de-registration. The following values are defined: o PERMANENT_TERMINATION (0) o NEW_SIP_SERVER_ASSIGNED (1) o SIP_SERVER_CHANGE (2) o REMOVE_SIP_SERVER (3) 8.7.2. SIP-Reason-Info AVP The SIP-Reason-Info AVP (AVP code xx18) [Note to IANA and the RFC editor: replace xx18 with the actual value allocated to this AVP] is of type UTF8String, and contains textual information that can be rendered to the user, about the reason for a de-registration. 8.8. SIP-AOR AVP The SIP-AOR AVP is a RADIUS attribute imported from the RADIUS Extension for Digest Authentication [I-D.ietf-radext-digest-auth] namespace, allowing a smooth transition between RADIUS and Diameter applications supporting SIP. The SIP-AOR AVP carries the URI of the intended user related to the SIP request (whose location in SIP may vary depending on the actual SIP request and whether the SIP server Garcia-Martin, et al. Expires March 25, 2006 [Page 58] Internet-Draft Diameter SIP Application September 2005 is acting on Diameter due to a SIP originated or terminating requests). The Diameter client (SIP server) uses the value found in a SIP Request-URI or a header field value of the SIP request to construct the SIP-AOR AVP. The selection of a Request-URI or a particular header field to create the value of the SIP-AOR AVP depends on the semantics of the SIP message and whether the SIP server is acting for originating or terminating requests. For instance, when the SIP server receives an INVITE request addressed to the served user (e.g., the SIP server is receiving a terminating SIP request), it maps the SIP Request-URI of the SIP request to this AVP. However, when the SIP server receives an INVITE request originated by the served user, it can map either the P-Asserted-Identity or the From header field values to this AVP. If the SIP server is acting as a SIP registrar, then it maps the To header field of the REGISTER request to the SIP- AOR AVP. 8.9. SIP-Visited-Network-Id AVP The SIP-Visited-Network-Id AVP (AVP Code xx19) [Note to IANA and the RFC editor: replace xx19 with the actual value allocated to this AVP] is of type UTF8String. This AVP contains an identifier that helps the home network to identify the visited network (e.g. the visited network domain name), in order to authorize roaming to such visited network. 8.10. SIP-User-Authorization-Type AVP The SIP-User-Authorization-Type AVP (AVP code xx20) [Note to IANA and the RFC editor: replace xx20 with the actual value allocated to this AVP] is of type Enumerated, and indicates the type of user authorization being performed in a User Authorization operation, i.e., the Diameter User-Authorization-Request (UAR) command. The following values are defined: o REGISTRATION (0) This value is used in case of the initial registration or re- registration. This is the default value. o DE_REGISTRATION (1) This value is used in case of the de-registration. o REGISTRATION_AND_CAPABILITIES (2) This value is used in case of initial registration or re- registration when the SIP server explicitly requests the Diameter server to get capability information. This capability information will help the SIP server to allocate another SIP server to serve the user. Garcia-Martin, et al. Expires March 25, 2006 [Page 59] Internet-Draft Diameter SIP Application September 2005 8.11. SIP-Supported-User-Data-Type AVP The SIP-Supported-User-Data-Type AVP (AVP Code xx21) [Note to IANA and the RFC editor: replace xx21 with the actual value allocated to this AVP] is of type UTF8String, and contains a string that identifies the type of supported user data (user profile, see SIP- User-Data AVP (Section 8.12)) supported in the node. The AVP can be repeated, if the SIP server supports several user data types. In case of repetition, the Diameter client should order the different instances of this AVP according to its preferences. When the Diameter client inserts this AVP in a SAR message, it allows the Diameter client to provide an indication to the Diameter server of the types of user data supported by the SIP server. The Diameter server, upon inspection of these AVPs, will return a suitable SIP- User-Data AVP (Section 8.12) of the type indicated in the SIP-User- Data-Type AVP (Section 8.12.1). 8.12. SIP-User-Data AVP The SIP-User-Data AVP (AVP Code xx22) [Note to IANA and the RFC editor: replace xx22 with the actual value allocated to this AVP] is of type Grouped. This AVP allows the Diameter server to transport user specific data, such as a user profile, to the SIP server (in the Diameter client). The Diameter server selects a type of user data that is understood by the SIP server in the Diameter client, and has been indicated in a SIP-Supported-User-Data-Type AVP. In case the Diameter client indicated support for several types of user data, the Diameter server SHOULD choose the first type supported by the client. The SIP-User-Data grouped AVP contains a SIP-User-Data-Type AVP, that indicates the type of user data included in the SIP-User-Data- Contents-AVP. SIP-User-Data ::= < AVP Header: xx22 > { SIP-User-Data-Type } { SIP-User-Data-Contents } * [ AVP ] [Note to IANA and the RFC editor: replace xx22 with the actual value allocated to this AVP] 8.12.1. SIP-User-Data-Type AVP The SIP-User-Data AVP (AVP Code xx23) [Note to IANA and the RFC editor: replace xx23 with the actual value allocated to this AVP] is of type UTF8String, and contains a string that identifies the type of user data included in the SIP-User-Data AVP (Section 8.12). Garcia-Martin, et al. Expires March 25, 2006 [Page 60] Internet-Draft Diameter SIP Application September 2005 This document does not specify a convention to characterize the type of user data contained in the SIP-User-Data AVP (Section 8.12). It is believed that in most cases this feature will be used in environments controlled by a network administrator who can configure both the client and server to assign the same value type at the client and server. It is also RECOMMENDED that organizations developing their own profile of SIP-User-Data AVP (Section 8.12) allocate a type based on their canonical DNS name. For instance, organization "example.com" can define several types of SIP-User-Data and allocate the types "type1.dsa.example.com", "type2.dsa.example.com", and so on. This convention will avoid a clash in the allocation of types of SIP-User-Data AVP (Section 8.12). 8.12.2. SIP-User-Data-Contents AVP The SIP-User-Data-Contents AVP (AVP Code xx24) [Note to IANA and the RFC editor: replace xx24 with the actual value allocated to this AVP] is of type OctetString. The Diameter peers do not need to understand the value of this AVP. The AVP contains the user profile data required for a SIP server to give service to the user. 8.13. SIP-User-Data-Already-Available AVP The SIP-User-Data-Already-Available AVP (AVP code xx25) [Note to IANA and the RFC editor: replace xx25 with the actual value allocated to this AVP] is of type Enumerated, and gives an indication to the Diameter server about whether the Diameter client (SIP server) already got the portion of the user profile that it needs to serve the user. The following values are defined: o USER_DATA_NOT_AVAILABLE (0) The Diameter client (SIP server) does not have the data that it needs to serve the user. o USER_DATA_ALREADY_AVAILABLE (1) The Diameter client (SIP server) already has got the data that it needs to serve the user. 8.14. SIP-Method AVP The SIP-Method-AVP (AVP code xx26) [Note to IANA and the RFC editor: replace xx26 with the actual value allocated to this AVP] is of type UTF8String and contains the method of the SIP request that triggered the Diameter message. The Diameter server MUST use this AVP solely to for authorization of SIP requests, and MUST NOT use it to compute the Digest authentication. To compute the Digest authentication, the Diameter server MUST use the Digest-Method AVP instead. Garcia-Martin, et al. Expires March 25, 2006 [Page 61] Internet-Draft Diameter SIP Application September 2005 9. New Values for Existing AVPs This section defines new values that the Diameter SIP application extends to already existing AVPs. 9.1. Extension to the Result-Code AVP Values The Result-Code AVP is already defined in RFC 3588 [RFC3588]. In addition to the values already defined in RFC 3588 [RFC3588], the Diameter SIP application defines the following new Result-Code AVP values: 9.1.1. Success Result-Code AVP Values A Diameter peer uses Result-Code AVP values that fall into the success category to inform the remote peer that a request has been successfully completed. [Note to IANA and the RFC editor: replace 2xxy with the actual values allocated to the Result-Code AVP] o DIAMETER_FIRST_REGISTRATION 2xx1 The user was not previously registered. The Diameter server has now authorized the registration. o DIAMETER_SUBSEQUENT_REGISTRATION 2xx2 The user is already registered. The Diameter server has now authorized the re-registration. o DIAMETER_UNREGISTERED_SERVICE 2xx3 The user is not currently registered, but the requested service can still be granted to the user. o DIAMETER_SUCCESS_SERVER_NAME_NOT_STORED 2xx4 The request operation was successfully processed. The Diameter server does not keep a record of the SIP server address assigned to the user. o DIAMETER_SERVER_SELECTION 2xx5 The Diameter server has authorized the registration. The user has already a SIP server assigned, but it may be necessary to select a new SIP server for the user. o DIAMETER_SUCCESS_AUTH_SENT_SERVER_NOT_STORED 2xx6 The requested operation was successfully executed. The Diameter server is sending a number of authentication credentials in the answer message. The Diameter server does not keep a record of the SIP server. 9.1.2. Transient Failures Result-Code AVP Values A Diameter peer uses a Result-Code AVP value that falls in the transient failures category to inform the remote peer that a request Garcia-Martin, et al. Expires March 25, 2006 [Page 62] Internet-Draft Diameter SIP Application September 2005 could not be satisfied at the time it was received, but MAY be able to satisfy the request in the future. [Note to IANA and the RFC editor: replace 4xxy with the actual values allocated to the Result-Code AVP] o DIAMETER_USER_NAME_REQUIRED 4xx1 The Diameter request did not contain a User-Name AVP, and it is required to complete the transaction. The Diameter peer MAY attempt the request again including a User-Name AVP. 9.1.3. Permanent failures Result-Code AVP Values A Diameter peer uses a Result-Code AVP value that fall into the permanent failure category to inform the remote peer that the request failed and should not be attempted again. [Note to IANA and the RFC editor: replace 5xxy with the actual values allocated to the Result-Code AVP] o DIAMETER_ERROR_USER_UNKNOWN 5xx1 The SIP-AOR AVP value does not belong to a known user in this realm. o DIAMETER_ERROR_IDENTITIES_DONT_MATCH 5xx2 The value in one of the SIP-AOR AVPs is not allocated to the user specified in the User-Name AVP. o DIAMETER_ERROR_IDENTITY_NOT_REGISTERED 5xx3 A query for location information is received for a SIP AOR that has not been registered before. The user to which this identity belongs cannot be given service in this situation. o DIAMETER_ERROR_ROAMING_NOT_ALLOWED 5xx4 The user is not allowed to roam to the visited network. o DIAMETER_ERROR_IDENTITY_ALREADY_REGISTERED 5xx5 The identity being registered has already a server assigned and the registration status does not allow that it is overwritten. o DIAMETER_ERROR_AUTH_SCHEME_NOT_SUPPORTED 5xx6 The authentication scheme indicated in an authentication request is not supported. o DIAMETER_ERROR_IN_ASSIGNMENT_TYPE 5xx7 The SIP server address sent in the SIP-Server-URI AVP value of the Diameter Server-Assignment-Request (SAR) command is the same SIP server address that is currently assigned, but the SIP-Server- Assignment-Type AVP is not allowed, e.g., the user is registered and the Server-Assignment-Request indicates the assignment for an unregistered user. o DIAMETER_ERROR_TOO_MUCH_DATA 5xx8 The Diameter peer in the SIP server receives more data than it can accept. The SIP server cannot overwrite the already stored data. Garcia-Martin, et al. Expires March 25, 2006 [Page 63] Internet-Draft Diameter SIP Application September 2005 o DIAMETER_ERROR_NOT SUPPORTED_USER_DATA 5xx9 The SIP server informs Diameter server that the received subscription data contained information which was not recognized or supported. 10. Authentication Details Authenticating a user can occur through various mechanisms. Currently HTTP Digest authentication is supported. The actual authentication is performed in either the SIP server or the Diameter server. If the Diameter server wants to assure that authentication will take place in the own Diameter server (as opposed to a delegated authentication taking place in the SIP server), it MUST NOT include a Digest-HA1 AVP (part of the grouped SIP-Authenticate AVP which in turn is part of the SIP-Auth-Data-Item AVP) in a MAA message. The Diameter server MAY include a pre-calculated Digest-HA1 AVP in the MAA message if it wants to delegate authentication of the user to the SIP server. Note that on systems where the SIP User Agent is using HTTP Digest authentication [RFC2617] inside of TLS [RFC2246], where only the SIP proxy server has a certificate, delegating authentication to the SIP server (by making Digest-HA1 available to the SIP server) might reduce the load on the Diameter server. When requesting authentication, the Diameter client indicates in the SIP-Number-Auth-Items AVP value of a Diameter MAR message how many authentication credentials are being requested. In the Diameter MAA message, the Diameter server MAY include more than one SIP-Auth-Data- Item AVP, but it is only useful for the Diameter client if the the Digest-QoP AVP was set to 'auth-int' (in the MAR message), and if future authenticatiosn will have the same realm. On including more than one SIP-Auth-Data-Item AVP the Diameter server SHOULD indicate how many instances of SIP-Auth-Data-Item AVPs are present with the SIP-Number-Auth-Items AVP. This number may be different from the one requested in the Diameter MAR message. If multiple SIP-Auth-Data- Item AVPs are present, and their ordering is significant, the Diameter server MUST include a SIP-Item-Number AVP in each grouping to indicate the order. The SIP-Authentication-Scheme AVP will indicate "Digest" and the SIP-Authenticate AVP will contain data (typically a challenge of some kind) which the user can use for her authentication. The grouped SIP-Authorization AVP will contain the AVPs that conform the response which is expected from the user. If the Diameter server performs the authentication of the user, the Garcia-Martin, et al. Expires March 25, 2006 [Page 64] Internet-Draft Diameter SIP Application September 2005 Diameter MAR message that the Diameter client sends to the Diameter server MUST include all the authentication credentials supplied by the SIP UA (there might be more than one credential, e.g., different realms, authentication of proxies, etc.). Each credential is inserted in a grouped SIP-Authorization AVP (part of the grouped SIP- Auth-Data-Item AVP). The Diameter client MUST insert a SIP-Number- Auth-Items AVP with the value set to the number of credentials enclosed. If necessary, the Digest-Entity-Body-Hash AVP will contain a hash of the body, needed to perform the authentication. If the authentication is successful, the Diameter MAA message will contain a Result-Code AVP indicating success, and if necessary, the Diameter server MAY include one or more SIP-Auth-Data-Item AVPs to provide further authentication credentials to the SIP server. If the authentication is unsuccessful due to missing credentials, the Diameter MAA message will include an SIP-Auth-Data-Item AVP with the SIP-Authentication-Scheme and SIP-Authenticate AVPs containing data (typically a challenge of some kind) that the user can use to authenticate itself. There are situations where a SIP request traverses several proxies, and each of the proxies request to authenticate the SIP UA. In this situation, it is a valid scenario that a SIP request received at a SIP server contains several sets of credentials. The 'realm' directive in HTTP is the key that the Diameter client can use to determine which credential is applicable. It may happen also that none of the realms are of interests to the Diameter client, in which case the Diameter client MUST consider that no credentials (of interest) were sent. In any case, a Diameter client MUST send zero or exactly one credential to the Diameter server. The Diameter client MUST choose the credential based on the 'realm' directive in the Authorization/Proxy-Authorization header field, and it MUST match the realm of the Diameter client. 10.1. Generation of nonces This Diameter SIP application provides support for generating nonces in either the Diameter client of the Diameter server. Both Diameter clients and servers MUST support both modes of operation. The Diameter SIP application does not provide a mechanism to negotiate where the nonce is generated. The behaviour is preprovisioned in both the Diameter client and servers or, otherwise, derived from the operation. If HTTP Digest authentication using AKA [RFC3310] is used, then the Diameter server MUST generate always nonces and the Diameter client MUST NOT generate nonces. Garcia-Martin, et al. Expires March 25, 2006 [Page 65] Internet-Draft Diameter SIP Application September 2005 On receiving a SIP request that does not contain credentials, the SIP server (Diameter client) first decides whether nonces for the challenge will be generated locally in the Diameter client or remotely in the Diameter server. This, as indicated before, is typically a policy decision. If the result of such decision is that nonces are locally generated, then the SIP server/Diameter client MUST generate a challenge (including a nonce), that will be part of a SIP 401/407 (Proxy) Authentication Required. If the result of the decision is to generate the nonces in the Diameter server, then the Diameter client MUST send a Diameter Multimedia-Auth-Request (MAR) message to the Diameter server that does not contain a Digest-Nonce AVP, according to the procedures described in Section 7.7 11. Migration from RADIUS RADIUS offers support for HTTP Digest authentication in the RADIUS Extension for Digest Authentication [I-D.ietf-radext-digest-auth]. A number of AVPs (the Digest-* AVPs) of this Diameter SIP application are imported from the RADIUS attributes namespace, thus making the migration from RADIUS to Diameter smooth. Note that the RADIUS Extension for Digest Authentication [I-D.ietf- radext-digest-auth] provides a more limited scope than this Diameter SIP application, especially, the RADIUS extension for Digest Authentiation merely provides support for HTTP Digest authentication, whereas the Diameter SIP application provides, e.g., support for user location, profile downloading and update, etc. The following sections discuss several configurations in which a gateway translates RADIUS to Diameter and vice versa: 11.1. Gateway from RADIUS Client to Diameter Server The gateway maps Access-Request messages to MAR request. If a RADIUS Access-Request message contains at least one Digest-* attribute, the gateway maps all Digest-* attributes to the AVPs of a Diameter SIP- Authorization AVP, constructs a MAR message and sends it to the Diameter server. If the RADIUS Access-Request message does not contain any Digest-* attribute, then RADIUS client does not want to apply HTTP Digest authentication, in which case, actions at the gateway are outside the scope of this document. The Diameter Server responds with a MAA message. If the MAA message contains a Result-Code AVP set to the value DIAMETER_MULTI_ROUND_AUTH and challenge parameters in a SIP-Authenticate AVP, then the gateway translates the AVPs of SIP-Authenticate AVP and puts the resulting RADIUS attributes into an Access-Challenge message. It sends the Garcia-Martin, et al. Expires March 25, 2006 [Page 66] Internet-Draft Diameter SIP Application September 2005 Access-Challenge message to the RADIUS client. If the MAA message contains a SIP-Authentication-Info and a Digest- Response AVP. The gateway converts these AVPs to the corresponding RADIUS attributes and constructs a RADIUS message. If the Result- Code AVP is DIAMETER_SUCCESS, an Access-Accept is sent. In all other cases, an Access-Reject is sent. 11.2. Gateway from Diameter Client to RADIUS Server The Diameter client sends a Diameter MAR meesage to the gateway. If the MAR message does not contain SIP-Auth-Data-Item AVPs, the gateway constructs an Access-Request message and maps the SIP-AOR and SIP- Method AVPs to RADIUS attributes. The gateway sends the Access- Request message to the RADIUS server which will respond with an Access-Challenge. The gateway creates a MAA message with a Result- Code AVP set to DIAMETER_MULTI_ROUND_AUTH and maps the Digest-* attributes to Diameter AVPs in a SIP-Authenticate AVP. The gateway sends the resulting MAA to the Diameter client, which will respond with a new MAR. The gateway checks the SIP-Auth-Data-Item AVPs of this MAR for an AVP where the Digest-Realm AVP matches the locally configured realm value. It takes the AVPs from this SIP-Auth-Data-Item AVP, converts them into the corresponding RADIUS attributes and constructs a RADIUS Access-Request message. The gateway sends the Access-Request message to the RADIUS server. If the RADIUS server responds with an Access- Accept message, the gateway converts the RADIUS attributes to Diameter AVPs, constructs a MAA message with a Result-Code AVP set to DIAMETER_SUCCESS and sends this message to the Diameter client. If the RADIUS server responds with an Access-Reject message, the gateway converts the RADIUS attributes to Diameter AVPs, constructs a MAA message with a Result-Code AVP set to DIAMETER_ERROR_IDENTITIES_DONT_MATCH and sends this message to the Diameter client. 11.3. Known Limitations As mentioned earlier, there is not a 100% match between the Diameter SIP application and the RADIUS Extension for Digest Authentication [I-D.ietf-radext-digest-auth]. In particular, the RADIUS Extension for Digest Authentication [I-D.ietf-radext-digest-auth] does not offer equivalent functionality to the Diameter UAR/UAA, SAR/SAA, LIR/ LIA, RTR/RTA and PPR/PPA messages defined by this specification. 12. IANA Considerations Garcia-Martin, et al. Expires March 25, 2006 [Page 67] Internet-Draft Diameter SIP Application September 2005 This document serves as IANA registration request for a number of items that should be registered in the AAA parameters registry. 12.1. Application Identifier This document defines a standards-track Application-ID that falls into the Application Identifier standards-track address space defined by RFC 3588 [RFC3588] Section 11.3. This Application ID should be registered in the Application IDs sub-registry of the AAA parameters registry with the following data: ID values Name Reference ----------- ------------------------ --------- XXX Diameter Session Initiation [RFC YYYY] Protocol (SIP) Application [Note to IANA and the RFC Editor: replace XXX with the allocated number, YYYY with the RFC number of this specification] 12.2. Command Codes This document defines new standard commands, whose Command Codes are to be allocated within the standard permanent Command Codes address space defined in RFC 3588 [RFC3588] Section 11.2.1. These command codes should be registered in the Command Codes sub-registry of the AAA parameters registry. Table 1 in Section 7 contains the detailed list of Command Code names and values that are part of this Diameter application. 12.3. AVP Codes This document defines new standard AVPs, whose AVP Codes are to be allocated within the AVP Codes address space defined in RFC 3588 [RFC3588] Section 11.4. These AVP codes should be registered in the AVP Codes sub-registry of the AAA parameters registry. Table 2 in Section 8 contains the detailed list of AVP names and AVP codes that are part of this Diameter application. 12.4. Additional Values for the Result-Code AVP Value This document defines new standard Result-Code AVP values to be allocated within the Result-Code AVP address space defined in RFC 3588 [RFC3588] Section 14.4.1. These values should be listed in the Result-Code AVP values section of the AVP Specific Values sub- registry of the AAA parameters registry. Garcia-Martin, et al. Expires March 25, 2006 [Page 68] Internet-Draft Diameter SIP Application September 2005 Section 9.1.1 lists the new Result-Code AVP values that fall into the success category, according to RFC 3588 [RFC3588] Section 7.1.2. Section 9.1.2 lists the new Result-Code AVP values that fall into the transient failure category, according to RFC 3588 [RFC3588] Section 7.1.4. Section 9.1.3 lists the new Result-Code AVP values that fall into the permanent failures category, according to RFC 3588 [RFC3588] Section 7.1.5. 13. Security Considerations This memo does not describe a stand-alone protocol, but a particular application for the Diameter protocol [RFC3588]. Consequently, all the security considerations applicable to Diameter automatically apply to this memo. In particular, section 13 of RFC 3588 applies to this memo. This Diameter SIP application allows a Diameter client to use the properties of HTTP Digest authentication [RFC2617] by evaluating or sending to the Diameter server the credentials supplied by a user. When Section 4 of RFC 2617 [RFC2617] discusses HTTP Digest authentication, it is also applicable to this memo. This Diameter SIP application also allows a Diameter client to use the properties of HTTP Digest authentication using AKA [RFC3310] by evaluating or sending to the Diameter server the credentials supplied by a user. Section 5 of RFC 3310 [RFC3310] is also applicable to this memo. 14. Contributors The authors would like to thank the following contributors who made substantial contributions to this work: Pete McCann Lucent Jaako Rajaniemi Nokia Wolfgang Beck (Deutsche Telekom AG) provided the text in the Migration to RADIUS Section. 15. Acknowledgements The authors would like to thank Tony Johansson and Kevin Purser for Garcia-Martin, et al. Expires March 25, 2006 [Page 69] Internet-Draft Diameter SIP Application September 2005 their invaluable contribution to the start up of this application and the continuous progress. The authors would like to thank Daniel Warren, Jayshree Bharatia, Kuntal Chowdhury, Jari Arkko, Avi Lior, Wolfgang Beck, Ulrich Wiehe, Cullen Jennings, and Anu Leinonen for their reviews and valuable comments. The Diameter SIP Application is based on the Diameter Application for the Cx interface of the 3GPP IP Multimedia Subsystem [3GPP.29.229]. The authors would like to thank 3GPP Working Group CN4 for this work. 16. Changes With Respect Previous Versions Note to the RFC editor: Delete this section before publication as RFC. 16.1. Changes in draft-ietf-aaa-diameter-sip-app-08.txt from -08.txt o This version of the specification added support for the generation of nonces in the Diameter client. This change had impact throughout the whole document. o Fixed some errors indicating that the final verification of the user's credentials could only take place in the Diameter client if client nonces wheren't used. Now the text clarifies that this scenario is not possible when the combination of client nonces and MD5-sess happens. o The Migration from RADIUS Section has been imported from the RADIUS draft. 16.2. Changes in draft-ietf-aaa-diameter-sip-app-07.txt from -06.txt o Added Table 3 that includes a summary of all the AVPs defined by this specification are the AVP flags. o Title in Section 5.4 is changed to "SIP Server Requests Authentication and Authorization" o Fixed typo in Section 7.7 that compared MAR with UAR (about storing state). The comparison should have been done with SAR. o Section 8.5 wrongly indicated that the Diameter client could send a SIP-Authenticate AVP. Actually, the Diameter *** server *** is the peer that sends SIP-Authenticate AVPs. o The draft used to speak about "authentication vectors". The terminology has been replaced by "a number of authentication credentials", which is more aligned with HTTP Digest. o On Section 10, a paragraph that used to couple Digest-HA1 with the qop value has been removed: it was a left over from a previous version of the document. Garcia-Martin, et al. Expires March 25, 2006 [Page 70] Internet-Draft Diameter SIP Application September 2005 16.3. Changes in draft-ietf-aaa-diameter-sip-app-06.txt from -05.txt o The SIP-AOR AVP is now imported from the RADIUS Extension for Digest Authentication [I-D.ietf-radext-digest-auth]. More information of how to derive the SIP-AOR from the SIP message is provided. o The Authentication Details section now tries to clarify the possibility of delegation of authentication to the SIP server, and cases where it might unload the Diameter server. 16.4. Changes in draft-ietf-aaa-diameter-sip-app-05.txt from -04.txt o The Digest-* AVPs are imported from the RADIUS Extension for Digest Authentication [I-D.ietf-radext-digest-auth]. An introduction paragraph has been added in Section 8.5.1. o As a side effect of the above change, the SIP-Authentication- Context disappeared. This was a grouped AVP that only contained a Digest-Entity-Body-Hash AVP. The latter will remain (in the RADIUS draft). o The Digest-Expected-Response was considered not secure enough. Instead, the Digest-Expected-Response has been replaced by Digest- HA1, which contains a hash of A1 (see RFC 2617 [RFC2617] Section 3.2.2 for more details. This allows the Diameter server to delegate the final authentication to the Diameter client in a secure way. The Digest-HA1 AVP is also imported from RADIUS Extension for Digest Authentication [I-D.ietf-radext-digest-auth]. o The Digest-Digest-URI has been renamed as Digest-URI, as it is now imported from RADIUS Extension for Digest Authentication [I-D.ietf-radext-digest-auth]. o The SIP-Accounting-Information AVP was originally specified in the SAA command. It has been also added to the PPR command, so that it is possible that PPR updates the addresses of the accounting servers. o It has been clarified that when the Diameter client receives a answer command that contains the Result-Code AVP set to DIAMETER_USER_NAME_REQUIRED the SIP server will typically request authentication. Previously, the description seemed to indicate that this typical action applied to any Result-Code. o The TEL URI (RFC 2806bis) is now known as RFC 3966. o If multiple SIP proxies are authenticating the user, the SIP request may contain several Proxy-Authorization headers. The Diameter server cannot send all the credentials, since the Diameter server may be serving several common realms for which credentials exist. In this situation the Diameter server will not known which credentials to use. It has been clarified that the Diameter client MUST send only one set of credentials at a time, those belonging to the served realm. Garcia-Martin, et al. Expires March 25, 2006 [Page 71] Internet-Draft Diameter SIP Application September 2005 o Reference added to RFC 3588 when a Subscriber Locator Function can populate the Redirect-Host-Usage with the value ALL_USER. o The IANA registration section has clarified what are the registry and sub-registries where IANA needs to take an action. 16.5. Changes in draft-ietf-aaa-diameter-sip-app-04.txt from -03.txt o DIAMETER_SUCCESS_SERVER_NAME_NOT_STORED and DIAMETER_SUCCESS_SERVER_NOT_STORED have the same semantics: the former is kept, the latter is deleted. o Added a new Digest-Method AVP. This AVP contains the method used to compute the Digest authentication, and it is independent from the SIP-Method AVP. It has been clarified that Digest-Method is used for authentication whereas SIP-Method is used for authorization. o SIP-User-Data-Request-Type AVP is removed. Its purpose was to retrieve a fraction of the user profile. This seems to create expensive complexity, and we don't seem to have requirements to support this function anymore. o Fixed the general section layout. Some sections got, by accident, buried in deep level section. o The grouped SIP-Authenticate AVP allowed multiple instances of the Digest-Expected-Response AVP. However, since there can be only one expected response computed at the Diameter server, we now allow a single Digest-Expected-Response. o A note is added indicating that if Digest-Qop is set to "auth-int" in the SIP-Authentication-Info AVP, then the Diameter client (SIP server) is responsible to compute the "rspauth" value in the Digest Authentication-Info header. o This version of the draft provides support to identify the type of user data included in the SIP-User-Data AVP (this can contain a user profile). The following changes has been made: o * Added a new SIP-Supported-User-Data-Type AVP. * The old SIP-User-Data AVP is now a grouped AVP that contains two AVPs: SIP-User-Data-Type and SIP-User-Data-Contents. * Added a new SIP-User-Data-Type AVP. * Added a new SIP-User-Data-Contents (that contains the profile). This is equivalent to the old SIP-User-Data AVP. * All the above AVPs are visible in SAR, SAA, and PPR commands. * The new SIP-User-Data and SIP-Supported-User-Data-Type allows repetition (a server could potential send more than one profile; a client can express support for more than one type of profile). o Fixed a typo that defined the SIP-Visited-Network-Id AVP as an OctetString AVP rather than UTF-8. Garcia-Martin, et al. Expires March 25, 2006 [Page 72] Internet-Draft Diameter SIP Application September 2005 16.6. Changes in draft-ietf-aaa-diameter-sip-app-03.txt from -02.txt o A Diameter Subscriber Locator was either a Diameter Relay or a Diameter Redirect node. We have removed the Diameter Relay functionality, since Diameter relays will not relay CER/CEA messages, thus, a Diameter client will never be able to determine which Diameter applications are running in a given Diameter server. So a Diameter Subscriber Locator is implemented as a Diameter redirect node. o Section "Registration termination" has been rewritten. Now the procedures speak about SIP soft state management, rather than SIP registration, so this procedures are applicable to SIP event subscriptions as well. A discussion on how to couple Diameter user sessions with SIP soft states is also added o Added a new Digest-Expected-Response AVP that allows the Diameter server to send a pre-calculated expected digest response to the Diameter client. This is only applicable to the case when the SIP UA does not use client nonces. o The Authentication Details Section has been updated with the latest details of the authentication process. 16.7. Changes in draft-ietf-aaa-diameter-sip-app-02.txt from -01.txt o We have changed the type of the SIP-Authenticate, SIP- Authorization, SIP-Authentication-Info AVPs. Now, each is a grouped AVP and contains one or more AVPs that maps to the corresponding Digest parameter. This means that the Diameter server will receive in a different AVP each of the values of the different parameters contained in the Digest headers. This approach relieves the Diameter server of implementing a SIP parser to determine the values of each of the parameters. o Specifically added support for Digest AKA operation, as per RFC 3310 [RFC3310]. A Digest-AKA-Auts AVP is added. o List of authors trimmed. Contributors section added. o The SIP-Entity-Body-Hash is renamed to Digest-Entity-Body-Hash to be aligned with the rest of the Digest-* AVPs. o The NAS-Session-Key AVP has been deleted. We never knew why this AVP was here. o We have removed the support for key distribution. Specifically we have removed the Confidentiality-Key and Integrity-Key AVPs. 16.8. Changes in draft-ietf-aaa-diameter-sip-app-01.txt from -00.txt o The SIP-Authentication-Info AVP was mistakenly typed as OctetString. We changed it to UTF8String. Since SIP is encoded in UTF8String, there is no point in having an OctetString AVP here. Garcia-Martin, et al. Expires March 25, 2006 [Page 73] Internet-Draft Diameter SIP Application September 2005 o The SIP-Authentication-Context AVP is changed to be a grouped AVP. It contains a SIP-Entity-Body-Hash AVP that contains the hash of the entity body (e.g., the hash of the SDP [RFC2327]). This is because some authentication mechanisms require to make a hash of the entity body. Instead of sending the whole entity body to the Diameter server, it is more efficient to send the hash of the body. o Added a descriptive text indicating the intended use/actions of each command. o Removed references to PGP since it is deprecated in SIP. o We have focused on providing support for HTTP Digest authentication in SIP, since it is the mandatory authentication mechanism in SIP. Other documents can extend this one adding support for other authentication mechanisms if that is required in the future. o Added a Security Considerations section. o The scenario "Diameter server authenticates the user" had an error, because it was assuming that the MAR/MAA commands were used to download the user profile. However, MAR/MAA do not contain provisions to download any user profile. The solution is to add a SAR/SAA commands that allow the SIP server to get the user profile stored in the Diameter server. o Added the missing Redirect-Host-Usage and Redirect-Max-Cache-Time to all the answers. 16.9. Changes in draft-ietf-aaa-diameter-sip-app-00.txt from draft-belinchon-aaa-diameter-mm-app-01.txt o Application name changed to Diameter SIP application. o New Definitions section added. o New Applicability section added. o The problem of locating a Diameter server is addressed with the introduction of a new Diameter Subscriber Locator role. o Added new scenarios to indicate usage in a more generic Internet environment. o A few AVPs have been renamed to accurately reflect the intention of the AVP. For instance, SIP-Server-Name becomes SIP-Server-URI, and SIP-Public-User-ID becomes SIP-AOR. o MAR command can be used more generically. Particularly, it does not assume a SIP REGISTER message. So we had to add a new SIP- Method AVP to indicate the SIP method that triggered the MAR command. o User-Name is no longer mandatory in requests, as typically a SIP request will not contain a user name. As a result of this change, a new transit failure Result-Code AVP value has been added: DIAMETER_USER_NAME_REQUIRED, to indicate the Diameter client that the request didn't include a User-Name AVP and it is required to process it. Typically, SIP servers, upon reception of this Garcia-Martin, et al. Expires March 25, 2006 [Page 74] Internet-Draft Diameter SIP Application September 2005 Result-Code AVP value, will generate a SIP 401 (Unauthorized) or SIP 407 (Proxy Authentication Required) to request the user name from the user. o IANA section has been carefully rewritten to give detailed instructions to IANA on what is required to register. 17. References 17.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., Leach, P., Luotonen, A., and L. Stewart, "HTTP Authentication: Basic and Digest Access Authentication", RFC 2617, June 1999. [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [RFC3310] Niemi, A., Arkko, J., and V. Torvinen, "Hypertext Transfer Protocol (HTTP) Digest Authentication Using Authentication and Key Agreement (AKA)", RFC 3310, September 2002. [RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. Arkko, "Diameter Base Protocol", RFC 3588, September 2003. [I-D.ietf-radext-digest-auth] Sterman, B., "RADIUS Extension for Digest Authentication", draft-ietf-radext-digest-auth-05 (work in progress), September 2005. 17.2. Informational References [RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC 2246, January 1999. [RFC2327] Handley, M. and V. Jacobson, "SDP: Session Description Protocol", RFC 2327, April 1998. [RFC4004] Calhoun, P., Johansson, T., Perkins, C., Hiller, T., and P. McCann, "Diameter Mobile IPv4 Application", RFC 4004, August 2005. Garcia-Martin, et al. Expires March 25, 2006 [Page 75] Internet-Draft Diameter SIP Application September 2005 [RFC4005] Calhoun, P., Zorn, G., Spence, D., and D. Mitton, "Diameter Network Access Server Application", RFC 4005, August 2005. [RFC4006] Hakala, H., Mattila, L., Koskinen, J-P., Stura, M., and J. Loughney, "Diameter Credit-Control Application", RFC 4006, August 2005. [3GPP.29.229] 3GPP, "Cx and Dx interfaces based on the Diameter protocol; Protocol details", 3GPP TS 29.229 5.10.0, April 2005. Garcia-Martin, et al. Expires March 25, 2006 [Page 76] Internet-Draft Diameter SIP Application September 2005 Authors' Addresses Miguel A. Garcia Martin (editor) Nokia P.O. Box 407 NOKIA GROUP, FIN 00045 Finland Phone: +358 50 480 4586 Email: miguel.an.garcia@nokia.com Maria-Carmen Belinchon Ericsson Via de los Poblados 13 Madrid 28033 Spain Phone: +34 91 339 3535 Email: maria.carmen.belinchon@ericsson.com Miguel A. Pallares-Lopez Ericsson Via de los Poblados 13 Madrid 28033 Spain Phone: +34 91 339 4222 Email: miguel-angel.pallares@ericsson.com Carolina Canales-Valenzuela Ericsson Via de los Poblados 13 Madrid 28033 Spain Phone: +34 91 339 2680 Email: carolina.canales@ericsson.com Garcia-Martin, et al. Expires March 25, 2006 [Page 77] Internet-Draft Diameter SIP Application September 2005 Kalle Tammi Nokia P.O.Box 785 Tampere 33101 Finland Phone: +358 40 505 8670 Email: kalle.tammi@nokia.com Garcia-Martin, et al. Expires March 25, 2006 [Page 78] Internet-Draft Diameter SIP Application September 2005 Intellectual Property Statement 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 procedures with respect to rights in RFC 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. 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Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Garcia-Martin, et al. Expires March 25, 2006 [Page 79]