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diff --git a/lib/diameter/doc/standard/rfc4006.txt b/lib/diameter/doc/standard/rfc4006.txt new file mode 100644 index 0000000000..3f3e5e1d1b --- /dev/null +++ b/lib/diameter/doc/standard/rfc4006.txt @@ -0,0 +1,6387 @@ + + + + + + +Network Working Group H. Hakala +Request for Comments: 4006 L. Mattila +Category: Standards Track Ericsson + J-P. Koskinen + M. Stura + J. Loughney + Nokia + August 2005 + + + Diameter Credit-Control Application + +Status of This Memo + + This document specifies an Internet standards track protocol for the + Internet community, and requests discussion and suggestions for + improvements. Please refer to the current edition of the "Internet + Official Protocol Standards" (STD 1) for the standardization state + and status of this protocol. Distribution of this memo is unlimited. + +Copyright Notice + + Copyright (C) The Internet Society (2005). + +Abstract + + This document specifies a Diameter application that can be used to + implement real-time credit-control for a variety of end user services + such as network access, Session Initiation Protocol (SIP) services, + messaging services, and download services. + +Table of Contents + + 1. Introduction................................................. 4 + 1.1. Requirements Language................................. 5 + 1.2. Terminology........................................... 5 + 1.3. Advertising Application Support....................... 7 + 2. Architecture Models.......................................... 7 + 3. Credit-Control Messages...................................... 9 + 3.1. Credit-Control-Request (CCR) Command.................. 9 + 3.2. Credit-Control-Answer (CCA) Command................... 11 + 4. Credit-Control Application Overview.......................... 11 + 4.1. Service-Specific Rating Input and Interoperability.... 13 + 5. Session Based Credit-Control................................. 15 + 5.1. General Principles.................................... 15 + 5.2. First Interrogation................................... 21 + 5.3. Intermediate Interrogation............................ 27 + 5.4. Final Interrogation................................... 29 + + + +Hakala, et al. Standards Track [Page 1] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + 5.5. Server-Initiated Credit Re-Authorization.............. 30 + 5.6. Graceful Service Termination.......................... 32 + 5.7. Failure Procedures.................................... 38 + 6. One Time Event............................................... 41 + 6.1. Service Price Enquiry................................. 42 + 6.2. Balance Check......................................... 42 + 6.3. Direct Debiting....................................... 43 + 6.4. Refund................................................ 44 + 6.5. Failure Procedure..................................... 44 + 7. Credit-Control Application State Machine..................... 46 + 8. Credit-Control AVPs.......................................... 55 + 8.1. CC-Correlation-Id AVP................................. 58 + 8.2. CC-Request-Number AVP................................. 58 + 8.3. CC-Request-Type AVP................................... 58 + 8.4. CC-Session-Failover AVP............................... 59 + 8.5. CC-Sub-Session-Id AVP................................. 59 + 8.6. Check-Balance-Result AVP.............................. 60 + 8.7. Cost-Information AVP.................................. 60 + 8.8. Unit-Value AVP........................................ 61 + 8.9. Exponent AVP.......................................... 61 + 8.10. Value-Digits AVP...................................... 61 + 8.11. Currency-Code AVP..................................... 62 + 8.12. Cost-Unit AVP......................................... 62 + 8.13. Credit-Control AVP.................................... 62 + 8.14. Credit-Control-Failure-Handling AVP................... 62 + 8.15. Direct-Debiting-Failure-Handling AVP.................. 63 + 8.16. Multiple-Services-Credit-Control AVP.................. 64 + 8.17. Granted-Service-Unit AVP.............................. 65 + 8.18. Requested-Service-Unit AVP............................ 66 + 8.19. Used-Service-Unit AVP................................. 66 + 8.20. Tariff-Time-Change AVP................................ 67 + 8.21. CC-Time AVP........................................... 67 + 8.22. CC-Money AVP.......................................... 67 + 8.23. CC-Total-Octets AVP................................... 68 + 8.24. CC-Input-Octets AVP................................... 68 + 8.25. CC-Output-Octets AVP.................................. 68 + 8.26. CC-Service-Specific-Units AVP......................... 68 + 8.27. Tariff-Change-Usage AVP............................... 68 + 8.28. Service-Identifier AVP................................ 69 + 8.29. Rating-Group AVP...................................... 69 + 8.30. G-S-U-Pool-Reference AVP.............................. 69 + 8.31. G-S-U-Pool-Identifier AVP............................. 70 + 8.32. CC-Unit-Type AVP...................................... 70 + 8.33. Validity-Time AVP..................................... 70 + 8.34. Final-Unit-Indication AVP............................. 71 + 8.35. Final-Unit-Action AVP................................. 72 + 8.36. Restriction-Filter-Rule AVP........................... 72 + 8.37. Redirect-Server AVP................................... 73 + + + +Hakala, et al. Standards Track [Page 2] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + 8.38. Redirect-Address-Type AVP............................. 73 + 8.39. Redirect-Server-Address AVP........................... 74 + 8.40. Multiple-Services-Indicator AVP....................... 74 + 8.41. Requested-Action AVP.................................. 74 + 8.42. Service-Context-Id AVP................................ 75 + 8.43. Service-Parameter-Info AVP............................ 76 + 8.44. Service-Parameter-Type AVP............................ 76 + 8.45. Service-Parameter-Value AVP........................... 77 + 8.46. Subscription-Id AVP................................... 77 + 8.47. Subscription-Id-Type AVP.............................. 77 + 8.48. Subscription-Id-Data AVP.............................. 78 + 8.49. User-Equipment-Info AVP............................... 78 + 8.50. User-Equipment-Info-Type AVP.......................... 78 + 8.50. User-Equipment-Info-Value AVP......................... 79 + 9. Result Code AVP Values....................................... 79 + 9.1. Transient Failures.................................... 79 + 9.2. Permanent Failures.................................... 80 + 10. AVP Occurrence Table......................................... 80 + 10.1. Credit-Control AVP Table.............................. 81 + 10.2. Re-Auth-Request/Answer AVP Table...................... 82 + 11. RADIUS/Diameter Credit-Control Interworking Model............ 82 + 12. IANA Considerations.......................................... 85 + 12.1. Application Identifier................................ 86 + 12.2. Command Codes......................................... 86 + 12.3. AVP Codes............................................. 86 + 12.4. Result-Code AVP Values................................ 86 + 12.5. CC-Request-Type AVP................................... 86 + 12.6. CC-Session-Failover AVP............................... 86 + 12.7. CC-Unit-Type AVP...................................... 87 + 12.8. Check-Balance-Result AVP.............................. 87 + 12.9. Credit-Control AVP.................................... 87 + 12.10. Credit-Control-Failure-Handling AVP................... 87 + 12.11. Direct-Debiting-Failure-Handling AVP.................. 87 + 12.12. Final-Unit-Action AVP................................. 87 + 12.13. Multiple-Services-Indicator AVP....................... 87 + 12.14. Redirect-Address-Type AVP............................. 88 + 12.15. Requested-Action AVP.................................. 88 + 12.16. Subscription-Id-Type AVP.............................. 88 + 12.17. Tariff-Change-Usage AVP............................... 88 + 12.18. User-Equipment-Info-Type AVP.......................... 88 + 13. Credit-Control Application Related Parameters................ 88 + 14. Security Considerations...................................... 89 + 14.1. Direct Connection with Redirects...................... 90 + 15. References................................................... 91 + 15.1. Normative References.................................. 91 + 15.2. Informative References................................ 92 + 16. Acknowledgements............................................. 93 + Appendix A Credit-Control Sequences.............................. 94 + + + +Hakala, et al. Standards Track [Page 3] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + A.1. Flow I................................................ 94 + A.2. Flow II............................................... 96 + A.3. Flow III.............................................. 98 + A.4. Flow IV............................................... 99 + A.5. Flow V................................................ 100 + A.6. Flow VI............................................... 102 + A.7. Flow VII.............................................. 103 + A.8. Flow VIII............................................. 105 + A.9. Flow IX............................................... 107 + Authors' Addresses............................................... 112 + Full Copyright Statement......................................... 114 + +1. Introduction + + This document specifies a Diameter application that can be used to + implement real-time credit-control for a variety of end user services + such as network access, Session Initiation Protocol (SIP) services, + messaging services, and download services. It provides a general + solution to real-time cost and credit-control. + + The prepaid model has been shown to be very successful, for instance, + in GSM networks, where network operators offering prepaid services + have experienced a substantial growth of their customer base and + revenues. Prepaid services are now cropping up in many other + wireless and wire line based networks. + + In next generation wireless networks, additional functionality is + required beyond that specified in the Diameter base protocol. For + example, the 3GPP Charging and Billing requirements [3GPPCHARG] state + that an application must be able to rate service information in + real-time. In addition, it is necessary to check that the end user's + account provides coverage for the requested service prior to + initiation of that service. When an account is exhausted or expired, + the user must be denied the ability to compile additional chargeable + events. + + A mechanism has to be provided to allow the user to be informed of + the charges to be levied for a requested service. In addition, there + are services such as gaming and advertising that may credit as well + as debit a user account. + + The other Diameter applications provide service specific + authorization, and they do not provide credit authorization for + prepaid users. The credit authorization shall be generic and + applicable to all the service environments required to support + prepaid services. + + + + + +Hakala, et al. Standards Track [Page 4] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + To fulfill these requirements, it is necessary to facilitate credit- + control communication between the network element providing the + service (e.g., Network Access Server, SIP Proxy, and Application + Server) and a credit-control server. + + The scope of this specification is the credit authorization. Service + specific authorization and authentication is out of the scope. + +1.1. Requirements Language + + In this document, the key words "MAY", "MUST, "MUST NOT", "OPTIONAL", + "RECOMMENDED", "SHOULD", and "SHOULD NOT", are to be interpreted as + described in [KEYWORDS]. + +1.2. Terminology + + AAA + + Authentication, Authorization, and Accounting + + AA answer + + AA answer generically refers to a service specific authorization and + authentication answer. AA answer commands are defined in service + specific authorization applications, e.g., [NASREQ] and [DIAMMIP]. + + AA request + + AA request generically refers to a service specific authorization and + authentication request. AA request commands are defined in service + specific authorization applications e.g., [NASREQ] and [DIAMMIP]. + + Credit-control + + Credit-control is a mechanism that directly interacts in real-time + with an account and controls or monitors the charges related to the + service usage. Credit-control is a process of checking whether + credit is available, credit-reservation, deduction of credit from the + end user account when service is completed and refunding of reserved + credit that is not used. + + Diameter Credit-control Server + + A Diameter credit-control server acts as a prepaid server, performing + real-time rating and credit-control. It is located in the home + domain and is accessed by service elements or Diameter AAA servers in + + + + + +Hakala, et al. Standards Track [Page 5] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + real-time for purpose of price determination and credit-control + before the service event is delivered to the end-user. It may also + interact with business support systems. + + Diameter Credit-control Client + + A Diameter credit-control client is an entity that interacts with a + credit-control server. It monitors the usage of the granted quota + according to instructions returned by credit-control server. + + Interrogation + + The Diameter credit-control client uses interrogation to initiate a + session based credit-control process. During the credit-control + process, it is used to report the used quota and request a new one. + An interrogation maps to a request/answer transaction. + + One-time event + + Basically, a request/answer transaction of type event. + + Rating + + The act of determining the cost of the service event. + + Service + + A type of task performed by a service element for an end user. + + Service Element + + A network element that provides a service to the end users. The + Service Element may include the Diameter credit-control client, or + another entity (e.g., RADIUS AAA server) that can act as a Credit- + control client on behalf of the Service Element. In the latter case, + the interface between the Service Element and the Diameter credit- + control client is outside the scope of this specification. Examples + of the Service Elements include Network Access Server (NAS), SIP + Proxy, and Application Servers such as messaging server, content + server, and gaming server. + + Service Event + + An event relating to a service provided to the end user. + + + + + + + +Hakala, et al. Standards Track [Page 6] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Session based credit-control + + A credit-control process that makes use of several interrogations: + the first, a possible intermediate, and the final. The first + interrogation is used to reserve money from the user's account and to + initiate the process. The intermediate interrogations may be needed + to request new quota while the service is being rendered. The final + interrogation is used to exit the process. The credit-control server + is required to maintain session state for session-based credit- + control. + +1.3. Advertising Application Support + + Diameter nodes conforming to this specification MUST advertise + support by including the value of 4 in the Auth-Application-Id of the + Capabilities-Exchange-Request and Capabilities-Exchange-Answer + command [DIAMBASE]. + +2. Architecture Models + + The current accounting models specified in the Radius Accounting + [RFC2866] and Diameter base [DIAMBASE] are not sufficient for real- + time credit-control, where credit-worthiness is to be determined + prior to service initiation. Also, the existing Diameter + authorization applications, [NASREQ] and [DIAMMIP], only provide + service authorization, but do not provide credit authorization for + prepaid users. In order to support real-time credit-control, a new + type of server is needed in the AAA infrastructure: Diameter credit- + control server. The Diameter credit-control server is the entity + responsible for credit authorization for prepaid subscribers. + + A service element may authenticate and authorize the end user with + the AAA server by using AAA protocols; e.g., RADIUS or a Diameter + base protocol with a possible Diameter application. + + Accounting protocols such as RADIUS accounting and the Diameter base + accounting protocol can be used to provide accounting data to the + accounting server after service is initiated, and to provide possible + interim reports until service completion. However, for real-time + credit-control, these authorization and accounting models are not + sufficient. + + When real-time credit-control is required, the credit-control client + contacts the credit-control server with information about a possible + service event. The credit-control process is performed to determine + potential charges and to verify whether the end user's account + balance is sufficient to cover the cost of the service being + rendered. + + + +Hakala, et al. Standards Track [Page 7] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Figure 1 illustrates the typical credit-control architecture, which + consists of a Service Element with an embedded Diameter credit- + control client, a Diameter credit-control server, and an AAA server. + A Business Support System is usually deployed; it includes at least + the billing functionality. The credit-control server and AAA server + in this architecture model are logical entities. The real + configuration can combine them into a single host. The credit- + control protocol is the Diameter base protocol with the Diameter + credit-control application. + + When an end user requests services such as SIP or messaging, the + request is typically forwarded to a service element (e.g., SIP Proxy) + in the user's home domain. In some cases it might be possible that + the service element in the visited domain can offer services to the + end user; however, a commercial agreement must exist between the + visited domain and the home domain. Network access is an example of + a service offered in the visited domain where the NAS, through an AAA + infrastructure, authenticates and authorizes the user with the user's + home network. + + Service Element AAA and CC + +----------+ +---------+ Protocols+-----------+ +--------+ + | End |<---->|+-------+|<------------>| AAA | |Business| + | User | +->|| CC || | Server |->|Support | + | | | || Client||<-----+ | | |System | + +----------+ | |+-------+| | +-----------+ | | + | +---------+ | ^ +--------+ + +----------+ | | CC Protocol | ^ + | End |<--+ | +-----v----+ | + | User | +------>|Credit- | | + +----------+ Credit-Control |Control |--------+ + Protocol |Server | + +----------+ + + Figure 1: Typical credit-control architecture + + There can be multiple credit-control servers in the system for + redundancy and load balancing. The system can also contain separate + rating server(s), and accounts can be located in a centralized + database. To ensure that the end user's account is not debited or + credited multiple times for the same service event, only one place in + the credit-control system should perform duplicate detection. System + internal interfaces can exist to relay messages between servers and + an account manager. However, the detailed architecture of the + credit-control system and its interfaces are implementation specific + and are out of scope of this specification. + + + + + +Hakala, et al. Standards Track [Page 8] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Protocol transparent Diameter relays can exist between the credit- + control client and credit-control server. Also, Diameter Redirect + agents that refer credit-control clients to credit-control servers + and allow them to communicate directly can exist. These agents + transparently support the Diameter credit-control application. The + different roles of Diameter Agents are defined in Diameter base + [DIAMBASE], section 2.8. + + If Diameter credit-control proxies exist between the credit-control + client and the credit-control server, they MUST advertise the + Diameter credit-control application support. + +3. Credit-Control Messages + + This section defines new Diameter message Command-Code values that + MUST be supported by all Diameter implementations that conform to + this specification. The Command Codes are as follows: + + Command-Name Abbrev. Code Reference + ----------------------------------------------------------- + Credit-Control-Request CCR 272 3.1 + Credit-Control-Answer CCA 272 3.2 + + Diameter Base [DIAMBASE] defines in the section 3.2 the Command Code + ABNF specification. These formats are observed in Credit-Control + messages. + +3.1. Credit-Control-Request (CCR) Command + + The Credit-Control-Request message (CCR) is indicated by the + command-code field being set to 272 and the 'R' bit being set in the + Command Flags field. It is used between the Diameter credit-control + client and the credit-control server to request credit authorization + for a given service. + + The Auth-Application-Id MUST be set to the value 4, indicating the + Diameter credit-control application. + + + + + + + + + + + + + + +Hakala, et al. Standards Track [Page 9] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Message Format + + <Credit-Control-Request> ::= < Diameter Header: 272, REQ, PXY > + < Session-Id > + { Origin-Host } + { Origin-Realm } + { Destination-Realm } + { Auth-Application-Id } + { Service-Context-Id } + { CC-Request-Type } + { CC-Request-Number } + [ Destination-Host ] + [ User-Name ] + [ CC-Sub-Session-Id ] + [ Acct-Multi-Session-Id ] + [ Origin-State-Id ] + [ Event-Timestamp ] + *[ Subscription-Id ] + [ Service-Identifier ] + [ Termination-Cause ] + [ Requested-Service-Unit ] + [ Requested-Action ] + *[ Used-Service-Unit ] + [ Multiple-Services-Indicator ] + *[ Multiple-Services-Credit-Control ] + *[ Service-Parameter-Info ] + [ CC-Correlation-Id ] + [ User-Equipment-Info ] + *[ Proxy-Info ] + *[ Route-Record ] + *[ AVP ] + + + + + + + + + + + + + + + + + + + + +Hakala, et al. Standards Track [Page 10] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +3.2. Credit-Control-Answer (CCA) Command + + The Credit-Control-Answer message (CCA) is indicated by the command- + code field being set to 272 and the 'R' bit being cleared in the + Command Flags field. It is used between the credit-control server + and the Diameter credit-control client to acknowledge a Credit- + Control-Request command. + + Message Format + + <Credit-Control-Answer> ::= < Diameter Header: 272, PXY > + < Session-Id > + { Result-Code } + { Origin-Host } + { Origin-Realm } + { Auth-Application-Id } + { CC-Request-Type } + { CC-Request-Number } + [ User-Name ] + [ CC-Session-Failover ] + [ CC-Sub-Session-Id ] + [ Acct-Multi-Session-Id ] + [ Origin-State-Id ] + [ Event-Timestamp ] + [ Granted-Service-Unit ] + *[ Multiple-Services-Credit-Control ] + [ Cost-Information] + [ Final-Unit-Indication ] + [ Check-Balance-Result ] + [ Credit-Control-Failure-Handling ] + [ Direct-Debiting-Failure-Handling ] + [ Validity-Time] + *[ Redirect-Host] + [ Redirect-Host-Usage ] + [ Redirect-Max-Cache-Time ] + *[ Proxy-Info ] + *[ Route-Record ] + *[ Failed-AVP ] + *[ AVP ] + +4. Credit-Control Application Overview + + The credit authorization process takes place before and during + service delivery to the end user and generally requires the user's + authentication and authorization before any request is sent to the + credit-control server. The credit-control application defined in + this specification supports two different credit authorization + models: credit authorization with money reservation and credit + + + +Hakala, et al. Standards Track [Page 11] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + authorization with direct debiting. In both models, the credit- + control client requests credit authorization from the credit-control + server prior to allowing any service to be delivered to the end user. + + In the first model, the credit-control server rates the request, + reserves a suitable amount of money from the user's account, and + returns the corresponding amount of credit resources. Note that + credit resources may not imply actual monetary credit; credit + resources may be granted to the credit control client in the form of + units (e.g., data volume or time) to be metered. + + Upon receipt of a successful credit authorization answer with a + certain amount of credit resources, the credit-control client allows + service delivery to the end user and starts monitoring the usage of + the granted resources. When the credit resources granted to the user + have been consumed or the service has been successfully delivered or + terminated, the credit-control client reports back to the server the + used amount. The credit-control server deducts the used amount from + the end user's account; it may perform rating and make a new credit + reservation if the service delivery is continuing. This process is + accomplished with session based credit-control that includes the + first interrogation, possible intermediate interrogations, and the + final interrogation. For session based credit-control, both the + credit control client and the credit-control server are required to + maintain credit-control session state. Session based credit-control + is described in more detail, with more variations, in section 5. + + In contrast, credit authorization with direct debiting is a single + transaction process wherein the credit-control server directly + deducts a suitable amount of money from the user's account as soon as + the credit authorization request is received. Upon receipt of a + successful credit authorization answer, the credit-control client + allows service delivery to the end user. This process is + accomplished with the one-time event. Session state is not + maintained. + + In a multi-service environment, an end user can issue an additional + service request (e.g., data service) during an ongoing service (e.g., + voice call) toward the same account. Alternatively, during an active + multimedia session, an additional media type is added to the session, + causing a new simultaneous request toward same account. + Consequently, this needs to be considered when credit resources are + granted to the services. + + The credit-control application also supports operations such as + service price enquiry, user's balance check, and refund of credit on + the user's account. These operations are accomplished with the one- + time event. Session state is not maintained. + + + +Hakala, et al. Standards Track [Page 12] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + A flexible credit-control application specific failure handling is + defined in which the home service provider can model the credit- + control client behavior according to its own credit risk management + policy. + + The Credit-Control-Failure-Handling AVP and the Direct-Debiting- + Failure-Handling AVP are defined to determine what is done if the + sending of credit-control messages to the credit-control server has + been temporarily prevented. The usage of the Credit-Control- + Failure-Handling AVP and the Direct-Debiting-Failure-Handling AVP + allows flexibility, as failure handling for the credit-control + session and one time event direct debiting may be different. + +4.1. Service-Specific Rating Input and Interoperability + + The Diameter credit-control application defines the framework for + credit-control; it provides generic credit-control mechanisms + supporting multiple service applications. The credit-control + application, therefore, does not define AVPs that could be used as + input in the rating process. Listing the possible services that + could use this Diameter application is out of scope for this generic + mechanism. + + It is reasonable to expect that a service level agreement will exist + between providers of the credit-control client and the credit-control + server covering the charging, services offered, roaming agreements, + agreed rating input (i.e., AVPs), and so on. + + Therefore, it is assumed that a Diameter credit-control server will + provide service only for Diameter credit-control clients that have + agreed beforehand as to the content of credit-control messages. + Naturally, it is possible that any arbitrary Diameter credit-control + client can interchange credit-control messages with any Diameter + credit-control server, but with a higher likelihood that unsupported + services/AVPs could be present in the credit-control message, causing + the server to reject the request with an appropriate result-code. + +4.1.1. Specifying Rating Input AVPs + + There are two ways to provide rating input to the credit-control + server: either by using AVPs or by including them in the Service- + Parameter-Info AVP. The general principles for sending rating + parameters are as follows: + + 1a. The service SHOULD re-use existing AVPs if it can use AVPs + defined in existing Diameter applications (e.g., NASREQ for network + access services). Re-use of existing AVPs is strongly recommended in + [DIAMBASE]. + + + +Hakala, et al. Standards Track [Page 13] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + For AVPs of type Enumerated, the service may require a new value to + be defined. Allocation of new AVP values is done as specified in + [DIAMBASE], section 1.2. + + 1b. New AVPs can be defined if the existing AVPs do not provide + sufficient rating information. In this case, the procedures defined + in [DIAMBASE] for creating new AVPs MUST be followed. + + 1c. For services specific only to one vendor's implementation, a + Vendor-Specific AVP code for Private use can be used. Where a + Vendor-Specific AVP is implemented by more than one vendor, + allocation of global AVPs is encouraged instead; refer to [DIAMBASE]. + + 2. The Service-Parameter-Info AVP MAY be used as a container to pass + legacy rating information in its original encoded form (e.g., ASN.1 + BER). This method can be used to avoid unnecessary conversions from + an existing data format to an AVP format. In this case, the rating + input is embedded in the Service-Parameter-Info AVP as defined in + section 8.43. + + New service applications SHOULD favor the use of explicitly defined + AVPs as described in items 1a and 1b, to simplify interoperability. + +4.1.2. Service-Specific Documentation + + The service specific rating input AVPs, the contents of the Service- + Parameter-Info AVP or Service-Context-Id AVP (defined in section + 8.42) are not within the scope of this document. To facilitate + interoperability, it is RECOMMENDED that the rating input and the + values of the Service-Context-Id be coordinated via an informational + RFC or other permanent and readily available reference. The + specification of another cooperative standardization body (e.g., + 3GPP, OMA, and 3GPP2) SHOULD be used. However, private services may + be deployed that are subject to agreements between providers of the + credit-control server and client. In this case, vendor specific AVPs + can be used. + + This specification, together with the above service specific + documents, governs the credit-control message. Service specific + documents define which existing AVPs or new AVPs are used as input to + the rating process (i.e., those that do not define new credit-control + applications), and thus have to be included in the Credit-Control- + Request command by a Diameter credit-control client supporting a + given service as *[AVP]. Should Service-Parameter-Info be used, then + the service specific document MUST specify the exact content of this + grouped AVP. + + + + + +Hakala, et al. Standards Track [Page 14] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + The Service-Context-Id AVP MUST be included at the command level of a + Credit-Control Request to identify the service specific document that + applies to the request. The specific service or rating group the + request relates to is uniquely identified by the combination of + Service-Context-Id and Service-Identifier or Rating-Group. + +4.1.3. Handling of Unsupported/Incorrect Rating Input + + Diameter credit-control implementations are required to support the + Mandatory rating AVPs defined in service specific documentation of + the services they support, according to the 'M' bit rules in + [DIAMBASE]. + + If a rating input required for the rating process is incorrect in the + Credit-control request, or if the credit-control server does not + support the requested service context (identified by the Service- + Context-Id AVP at command level), the Credit-control answer MUST + contain the error code DIAMETER_RATING_FAILED. A CCA message with + this error MUST contain one or more Failed-AVP AVPs containing the + missing and/or unsupported AVPs that caused the failure. A Diameter + credit-control client that receives the error code + DIAMETER_RATING_FAILED in response to a request MUST NOT send similar + requests in the future. + +4.1.4. RADIUS Vendor-Specific Rating Attributes + + When service specific documents include RADIUS vendor specific + attributes that could be used as input in the rating process, the + rules described in [NASREQ] for formatting the Diameter AVP MUST be + followed. + + For example, if the AVP code used is the vendor attribute type code, + the Vendor-Specific flag MUST be set to 1 and the Vendor-ID MUST be + set to the IANA Vendor identification value. The Diameter AVP data + field contains only the attribute value of the RADIUS attribute. + +5. Session Based Credit-Control + +5.1. General Principles + + For a session-based credit-control, several interrogations are + needed: the first, intermediate (optional) and the final + interrogations. This is illustrated in Figures 2 and 3. + + If the credit-control client performs credit-reservation before + granting service to the end user, it MUST use several interrogations + toward the credit-control server (i.e., session based credit- + + + + +Hakala, et al. Standards Track [Page 15] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + control). In this case, the credit-control server MUST maintain the + credit-control session state. + + Each credit-control session MUST have a globally unique Session-Id as + defined in [DIAMBASE], which MUST NOT be changed during the lifetime + of a credit-control session. + + Certain applications require multiple credit-control sub-sessions. + These applications would send messages with a constant Session-Id + AVP, but with a different CC-Sub-Session-Id AVP. If several credit + sub-sessions will be used, all sub-sessions MUST be closed separately + before the main session is closed so that units per sub-session may + be reported. The absence of this AVP implies that no sub-sessions + are in use. + + Note that the service element might send a service specific re- + authorization message to the AAA server due to expiration of the + authorization-lifetime during an ongoing credit-control session. + However, the service specific re-authorization does not influence the + credit authorization that is ongoing between the credit-control + client and credit-control server, as credit authorization is + controlled by the burning rate of the granted quota. + + If service specific re-authorization fails, the user will be + disconnected, and the credit-control client MUST send a final + interrogation to the credit-control server. + + The Diameter credit-control server may seek to control the validity + time of the granted quota and/or the production of intermediate + interrogations. Thus, it MAY include the Validity-Time AVP in the + answer message to the credit-control client. Upon expiration of the + Validity-Time, the credit-control client MUST generate a credit- + control update request and report the used quota to the credit- + control server. It is up to the credit-control server to determine + the value of the Validity-Time to be used for consumption of the + granted service units. If the Validity-Time is used, its value + SHOULD be given as input to set the session supervision timer Tcc + (the session supervision timer MAY be set to two times the value of + the Validity-Time, as defined in section 13). Since credit-control + update requests are also produced at the expiry of granted service + units and/or for mid-session service events, the omission of + Validity-Time does not mean that intermediate interrogation for the + purpose of credit-control is not performed. + + + + + + + + +Hakala, et al. Standards Track [Page 16] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +5.1.1. Basic Tariff-Time Change Support + + The Diameter credit-control server and client MAY optionally support + a tariff change mechanism. The Diameter credit-control server may + include a Tariff-Time-Change AVP in the answer message. Note that + the granted units should be allocated based on the worst-case + scenario in case of forthcoming tariff change, so that the overall + reported used units would never exceed the credit reservation. + + When the Diameter credit-control client reports the used units and a + tariff change has occurred during the reporting period, the Diameter + credit-control client MUST separately itemize the units used before + and after the tariff change. If the client is unable to distinguish + whether units straddling the tariff change were used before or after + the tariff change, the credit-control client MUST itemize those units + in a third category. + + If a client does not support the tariff change mechanism and it + receives a CCA message carrying the Tariff-Time-Change AVP, it MUST + terminate the credit-control session, giving a reason of + DIAMETER_BAD_ANSWER in the Termination-Cause AVP. + + For time based services, the quota is continuously consumed at the + regular rate of 60 seconds per minute. At the time when credit + resources are allocated, the server already knows how many units will + be consumed before the tariff time change and how many units will be + consumed afterward. Similarly, the server can determine the units + consumed at the before rate and the units consumed at the rate + afterward in the event that the end-user closes the session before + the consumption of the allotted quota. There is no need for + additional traffic between client and server in the case of tariff + time changes for continuous time based service. Therefore, the + tariff change mechanism is not used for such services. For time- + based services in which the quota is NOT continuously consumed at a + regular rate, the tariff change mechanism described for volume and + event units MAY be used. + +5.1.2. Credit-Control for Multiple Services within a (sub-)Session + + When multiple services are used within the same user session and each + service or group of services is subject to different cost, it is + necessary to perform credit-control for each service independently. + Making use of credit-control sub-sessions to achieve independent + credit-control will result in increased signaling load and usage of + resources in both the credit-control client and the credit-control + server. For instance, during one network access session the end user + may use several http-services subject to different access cost. The + network access specific attributes such as the quality of service + + + +Hakala, et al. Standards Track [Page 17] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + (QoS) are common to all the services carried within the access + bearer, but the cost of the bearer may vary depending on its content. + + To support these scenarios optimally, the credit-control application + enables independent credit-control of multiple services in a single + credit-control (sub-)session. This is achieved by including the + optional Multiple-Services-Credit-Control AVP in Credit-Control- + Request/Answer messages. It is possible to request and allocate + resources as a credit pool shared between multiple services. The + services can be grouped into rating groups in order to achieve even + further aggregation of credit allocation. It is also possible to + request and allocate quotas on a per service basis. Where quotas are + allocated to a pool by means of the Multiple-Services-Credit-Control + AVP, the quotas remain independent objects that can be re-authorized + independently at any time. Quotas can also be given independent + result codes, validity times, and Final-Unit-Indications. + + A Rating-Group gathers a set of services, identified by a Service- + Identifier, and subject to the same cost and rating type (e.g., + $0.1/minute). It is assumed that the service element is provided + with Rating-Groups, Service-Identifiers, and their associated + parameters that define what has to be metered by means outside the + scope of this specification. (Examples of parameters associated to + Service-Identifiers are IP 5-tuple and HTTP URL.) Service-Identifiers + enable authorization on a per-service based credit as well as + itemized reporting of service usage. It is up to the credit-control + server whether to authorize credit for one or more services or for + the whole rating-group. However, the client SHOULD always report + used units at the finest supported level of granularity. Where quota + is allocated to a rating-group, all the services belonging to that + group draw from the allotted quota. The following is a graphical + representation of the relationship between service-identifiers, + rating-groups, credit pools, and credit-control (sub-)session. + + DCC (Sub-)Session + | + +------------+-----------+-------------+--------------- + + | | | | | + Service-Id a Service-Id b Service-Id c Service-Id d.....Service-Id z + \ / \ / / + \ / \ / / + \ / Rating-Group 1.......Rating-Group n + \ / | | + Quota ---------------Quota Quota + | / | + | / | + Credit-Pool Credit-Pool + + + + +Hakala, et al. Standards Track [Page 18] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + If independent credit-control of multiple services is used, the + validity-time and final-unit-indication SHOULD be present either in + the Multiple-Services-Credit-Control AVP(s) or at command level as + single AVPs. However, the Result-Code AVP MAY be present both on the + command level and within the Multiple-Services-Credit-Control AVP. + If the Result-Code on the command level indicates a value other than + SUCCESS, then the Result-Code on command level takes precedence over + any included in the Multiple-Services-Credit-Control AVP. + + The credit-control client MUST indicate support for independent + credit-control of multiple services within a (sub-)session by + including the Multiple-Services-Indicator AVP in the first + interrogation. A credit-control server not supporting this feature + MUST treat the Multiple-Services-Indicator AVP and any received + Multiple-Services-Credit-Control AVPs as invalid AVPs. + + If the client indicated support for independent credit-control of + multiple services, a credit-control server that wishes to use the + feature MUST return the granted units within the Multiple-Services- + Credit-Control AVP associated to the corresponding service-identifier + and/or rating-group. + + To avoid a situation where several parallel (and typically also + small) credit reservations must be made on the same account (i.e., + credit fragmentation), and also to avoid unnecessary load on the + credit-control server, it is possible to provide service units as a + pool that applies to multiple services or rating groups. This is + achieved by providing the service units in the form of a quota for a + particular service or rating group in the Multiple-Services-Credit- + Control AVP, and also by including a reference to a credit pool for + that unit type. + + The reference includes a multiplier derived from the rating + parameter, which translates from service units of a specific type to + the abstract service units in the pool. For instance, if the rating + parameter for service 1 is $1/MB and the rating parameter for service + 2 is $0.5/MB, the multipliers could be 10 and 5 for services 1 and 2, + respectively. + + If S is the total service units within the pool, M1, M2, ..., Mn are + the multipliers provided for services 1, 2, ..., n, and C1, C2, ..., + Cn are the used resources within the session, then the pool credit is + exhausted and re-authorization MUST be sought when: + + C1*M1 + C2*M2 + ... + Cn*Mn >= S + + + + + + +Hakala, et al. Standards Track [Page 19] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + The total credit in the pool, S, is calculated from the quotas, which + are currently allocated to the pool as follows: + + S = Q1*M1 + Q2*M2 + ... + Qn*Mn + + If services or rating groups are added to or removed from the pool, + then the total credit is adjusted appropriately. Note that when the + total credit is adjusted because services or rating groups are + removed from the pool, the value that need to be removed is the + consumed one (i.e., Cx*Mx). + + Re-authorizations for an individual service or rating group may be + sought at any time; for example, if a 'non-pooled' quota is used up + or the Validity-Time expires. + + Where multiple G-S-U-Pool-Reference AVPs (section 8.30) with the same + G-S-U-Pool-Identifier are provided within a Multiple-Services- + Credit-Control AVP (section 8.16) along with the Granted-Service-Unit + AVP, then these MUST have different CC-Unit-Type values, and they all + draw from the credit pool separately. For instance, if one + multiplier for time (M1t) and one multiplier for volume (M1v) are + given, then the used resources from the pool is the sum C1t*M1t + + C1v*M1v, where C1t is the time unit and C1v is the volume unit. + + Where service units are provided within a Multiple-Services-Credit- + Control AVP without a corresponding G-S-U-Pool-Reference AVP, then + these are handled independently from any credit pool and from any + other services or rating groups within the session. + + The credit pool concept is an optimal tool to avoid the over- + reservation effect of the basic single quota tariff time change + mechanism (the mechanism described in section 5.1.1). Therefore, + Diameter credit-control clients and servers implementing the + independent credit-control of multiple services SHOULD leverage the + credit pool concept when supporting the tariff time change. The + Diameter credit-control server SHOULD include both the Tariff-Time- + Change and Tariff-Change-Usage AVPs in two quota allocations in the + answer message (i.e., two instances of the Multiple-Services-Credit- + Control AVP). One of the granted units is allocated to be used + before the potential tariff change, while the second granted units + are for use after a tariff change. Both granted unit quotas MUST + contain the same Service-Identifier and/or Rating-Group. This dual + quota mechanism ensures that the overall reported used units would + never exceed the credit reservation. The Diameter credit-control + client reports both the used units before and after the tariff change + in a single instance of the Multiple-Services-Credit-Control AVP. + + + + + +Hakala, et al. Standards Track [Page 20] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + The failure handling for credit-control sessions is defined in + section 5.7 and reflected in the basic credit-control state machine + in section 7. Credit-control clients and servers implementing the + independent credit-control of multiple services in a (sub-)session + functionality MUST ensure failure handling and general behavior fully + consistent with the above mentioned sections, while maintaining the + ability to handle parallel ongoing credit re-authorization within a + (sub-)session. Therefore, it is RECOMMENDED that Diameter credit- + control clients maintain a PendingU message queue and restart the Tx + timer (section 13) every time a CCR message with the value + UPDATE_REQUEST is sent while they are in PendingU state. When + answers to all pending messages are received, the state machine moves + to OPEN state, and Tx is stopped. Naturally, the action performed + when a problem for the session is detected according to section 5.7 + affects all the ongoing services (e.g., failover to a backup server + if possible affect all the CCR messages with the value UPDATE_REQUEST + in the PendingU queue). + + Since the client may send CCR messages with the value UPDATE_REQUEST + while in PendingU (i.e., without waiting for an answer to ongoing + credit re-authorization), the time space between these requests may + be very short, and the server may not have received the previous + request(s) yet. Therefore, in this situation the server may receive + out of sequence requests and SHOULD NOT consider this an error + condition. A proper answer is to be returned to each of those + requests. + +5.2. First Interrogation + + When session based credit-control is required (e.g., the + authentication server indicated a prepaid user), the first + interrogation MUST be sent before the Diameter credit-control client + allows any service event to the end user. The CC-Request-Type is set + to the value INITIAL_REQUEST in the request message. + + If the Diameter credit-control client knows the cost of the service + event (e.g., a content server delivering ringing tones may know their + cost) the monetary amount to be charged is included in the + Requested-Service-Unit AVP. If the Diameter credit-control client + does not know the cost of the service event, the Requested-Service- + Unit AVP MAY contain the number of requested service events. Where + the Multiple-Services-Credit-Control AVP is used, it MUST contain the + Requested-Service-Unit AVP to indicate that the quota for the + associated service/rating-group is requested. In the case of + multiple services, the Service-Identifier AVP or the Rating-Group AVP + within the Multiple-Services-Credit-Control AVP always indicates the + service concerned. Additional service event information to be rated + + + + +Hakala, et al. Standards Track [Page 21] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + MAY be sent as service specific AVPs or MAY be sent within the + Service-Parameter-Info AVP at command level. The Service-Context-Id + AVP indicates the service specific document applicable to the + request. + + The Event-Timestamp AVP SHOULD be included in the request and + contains the time when the service event is requested in the service + element. The Subscription-Id AVP SHOULD be included to identify the + end user in the credit-control server. The credit-control client MAY + include the User-Equipment-Info AVP so that the credit-control server + has some indication of the type and capabilities of the end user + access device. How the credit-control server uses this information + is outside the scope of this document. + + The credit-control server SHOULD rate the service event and make a + credit-reservation from the end user's account that covers the cost + of the service event. If the type of the Requested-Service-Unit AVP + is money, no rating is needed, but the corresponding monetary amount + is reserved from the end user's account. + + The credit-control server returns the Granted-Service-Unit AVP in the + Answer message to the Diameter credit-control client. The Granted- + Service-Unit AVP contains the amount of service units that the + Diameter credit-control client can provide to the end user until a + new Credit-Control-Request MUST be sent to the credit-control server. + If several unit types are sent in the Answer message, the credit- + control client MUST handle each unit type separately. The type of + the Granted-Service-Unit AVP can be time, volume, service specific, + or money, depending on the type of service event. The unit type(s) + SHOULD NOT be changed within an ongoing credit-control session. + + There MUST be a maximum of one instance of the same unit type in one + Answer message. However, if multiple quotas are conveyed to the + credit-control client in the Multiple-Services-Credit-Control AVPs, + it is possible to carry two instances of the same unit type + associated to a service-identifier/rating-group. This is typically + the case when a tariff time change is expected and the credit-control + server wants to make a distinction between the granted quota before + and after tariff change. + + If the credit-control server determines that no further control is + needed for the service, it MAY include the result code indicating + that the credit-control is not applicable (e.g., if the service is + free of charge). This result code at command level implies that the + credit-control session is to be terminated. + + The Credit-Control-Answer message MAY also include the Final-Unit- + Indication AVP to indicate that the answer message contains the final + + + +Hakala, et al. Standards Track [Page 22] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + units for the service. After the end user has consumed these units, + the Diameter credit-control-client MUST behave as described in + section 5.6. + + This document defines two different approaches to perform the first + interrogation to be used in different network architectures. The + first approach uses credit-control messages after the user's + authorization and authentication takes place. The second approach + uses service specific authorization messages to perform the first + interrogation during the user's authorization/authentication phase, + and credit-control messages for the intermediate and final + interrogations. If an implementation of the credit-control client + supports both the methods, determining which method to use SHOULD be + configurable. + + In service environments such as the Network Access Server (NAS), it + is desired to perform the first interrogation as part of the + authorization/authentication process for the sake of protocol + efficiency. Further credit authorizations after the first + interrogation are performed with credit-control commands defined in + this specification. Implementations of credit-control clients + operating in the mentioned environments SHOULD support this method. + If the credit-control server and AAA server are separate physical + entities, the service element sends the request messages to the AAA + server, which then issues an appropriate request or proxies the + received request forward to the credit-control server. + + In other service environments, such as the 3GPP network and some SIP + scenarios, there is a substantial decoupling between + registration/access to the network and the actual service request + (i.e., the authentication/authorization is executed once at + registration/access to the network and is not executed for every + service event requested by the subscriber). In these environments, + it is more appropriate to perform the first interrogation after the + user has been authenticated and authorized. The first, the + intermediate, and the final interrogations are executed with credit- + control commands defined in this specification. + + Other IETF standards or standards developed by other standardization + bodies may define the most suitable method in their architectures. + +5.2.1. First Interrogation after Authorization and Authentication + + The Diameter credit-control client in the service element may get + information from the authorization server as to whether credit- + control is required, based on its knowledge of the end user. If + credit-control is required the credit-control server needs to be + contacted prior to initiating service delivery to the end user. The + + + +Hakala, et al. Standards Track [Page 23] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + accounting protocol and the credit-control protocol can be used in + parallel. The authorization server may also determine whether the + parallel accounting stream is required. + + The following diagram illustrates the case where both protocols are + used in parallel and the service element sends credit-control + messages directly to the credit-control server. More credit-control + sequence examples are given in Annex A. + + Diameter + End User Service Element AAA Server CC Server + (CC Client) + | Registration | AA request/answer(accounting,cc or both)| + |<----------------->|<------------------>| | + | : | | | + | : | | | + | Service Request | | | + |------------------>| | | + | | CCR(Initial,Credit-Control AVPs) | + | +|---------------------------------------->| + | CC stream|| | CCA(Granted-Units)| + | +|<----------------------------------------| + | Service Delivery | | | + |<----------------->| ACR(start,Accounting AVPs) | + | : |------------------->|+ | + | : | ACA || Accounting stream | + | |<-------------------|+ | + | : | | | + | : | | | + | | CCR(Update,Used-Units) | + | |---------------------------------------->| + | | | CCA(Granted-Units)| + | |<----------------------------------------| + | : | | | + | : | | | + | End of Service | | | + |------------------>| CCR(Termination, Used-Units) | + | |---------------------------------------->| + | | | CCA | + | |<----------------------------------------| + | | ACR(stop) | | + | |------------------->| | + | | ACA | | + | |<-------------------| | + + Figure 2: Protocol example with first interrogation after user's + authorization/authentication + + + + +Hakala, et al. Standards Track [Page 24] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +5.2.2. Authorization Messages for First Interrogation + + The Diameter credit-control client in the service element MUST + actively co-operate with the authorization/authentication client in + the construction of the AA request by adding appropriate credit- + control AVPs. The credit-control client MUST add the Credit-Control + AVP to indicate credit-control capabilities and MAY add other + relevant credit-control specific AVPs to the proper + authorization/authentication command to perform the first + interrogation toward the home Diameter AAA server. The Auth- + Application-Id is set to the appropriate value, as defined in the + relevant service specific authorization/authentication application + document (e.g., [NASREQ], [DIAMMIP]). The home Diameter AAA server + authenticates/authorizes the subscriber and determines whether + credit-control is required. + + If credit-control is not required for the subscriber, the home + Diameter AAA server will respond as usual, with an appropriate AA + answer message. If credit-control is required for the subscriber and + the Credit-Control AVP with the value set to CREDIT_AUTHORIZATION was + present in the authorization request, the home AAA server MUST + contact the credit-control server to perform the first interrogation. + If credit-control is required for the subscriber and the Credit- + Control AVP was not present in the authorization request, the home + AAA server MUST send an authorization reject answer message. + + The Diameter AAA server supporting credit-control is required to send + the Credit-Control-Request command (CCR) defined in this document to + the credit-control server. The Diameter AAA server populates the CCR + based on service specific AVPs used for input to the rating process, + and possibly on credit-control AVPs received in the AA request. The + credit-control server will reserve money from the user's account, + will rate the request and will send a Credit-Control-Answer message + to the home Diameter AAA server. The answer message includes the + Granted-Service-Unit AVP(s) and MAY include other credit-control + specific AVPs, as appropriate. Additionally, the credit-control + server MAY set the Validity-Time and MAY include the Credit-Control- + Failure-Handling AVP and the Direct-Debiting-Failure-Handling AVP to + determine what to do if the sending of credit-control messages to the + credit-control server has been temporarily prevented. + + Upon receiving the Credit-Control-Answer message from the credit- + control server, the home Diameter AAA server will populate the AA + answer with the received credit-control AVPs and with the appropriate + service attributes according to the authorization/authentication + specific application (e.g., [NASREQ], [DIAMMIP]). It will then + forward the packet to the credit-control client. If the home + Diameter AAA server receives a credit-control reject message, it will + + + +Hakala, et al. Standards Track [Page 25] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + simply generate an appropriate authorization reject message to the + credit-control client, including the credit-control specific error + code. + + In this model, the credit-control client sends further credit-control + messages to the credit-control server via the home Diameter AAA + server. Upon receiving a successful authorization answer message + with the Granted-Service-Unit AVP(s), the credit-control client will + grant the service to the end user and will generate an intermediate + credit-control request, as required by using credit-control commands. + The CC-Request-Number of the first UPDATE_REQUEST MUST be set to 1 + (for how to produce unique value for the CC-Request-Number AVP, see + section 8.2). + + If service specific re-authorization is performed (i.e., + authorization-lifetime expires), the credit-control client MUST add + to the service specific re-authorization request the Credit-Control + AVP with a value set to RE_AUTHORIZATION to indicate that the + credit-control server MUST NOT be contacted. When session based + credit-control is used for the subscriber, a constant credit-control + message stream flows through the home Diameter AAA server. The home + Diameter AAA server can make use of this credit-control message flow + to deduce that the user's activity is ongoing; therefore, it is + recommended to set the authorization-lifetime to a reasonably high + value when credit-control is used for the subscriber. + + In this scenario, the home Diameter AAA server MUST advertise support + for the credit-control application to its peers during the capability + exchange process. + + + + + + + + + + + + + + + + + + + + + + +Hakala, et al. Standards Track [Page 26] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + The following diagram illustrates the use of + authorization/authentication messages to perform the first + interrogation. The parallel accounting stream is not shown in the + figure. + + Service Element Diameter + End User (CC Client) AAA Server CC Server + | Service Request | AA Request (CC AVPs) | + |------------------>|------------------->| | + | | | CCR(Initial, CC AVPs) + | | |------------------->| + | | | CCA(Granted-Units) + | | |<-------------------| + | | AA Answer(Granted-Units) | + | Service Delivery |<-------------------| | + |<----------------->| | | + | : | | | + | : | | | + | : | | | + | | | | + | | CCR(Update,Used-Units) | + | |------------------->| CCR(Update,Used-Units) + | | |------------------->| + | | | CCA(Granted-Units)| + | | CCA(Granted-Units)|<-------------------| + | |<-------------------| | + | : | | | + | : | | | + | End of Service | | | + |------------------>| CCR(Termination,Used-Units) | + | |------------------->| CCR(Term.,Used-Units) + | | |------------------->| + | | | CCA | + | | CCA |<-------------------| + | |<-------------------| | + + Figure 3: Protocol example with use of the + authorization messages for the first interrogation + +5.3. Intermediate Interrogation + + When all the granted service units for one unit type are spent by the + end user or the Validity-Time is expired, the Diameter credit-control + client MUST send a new Credit-Control-Request to the credit-control + server. In the event that credit-control for multiple services is + applied in one credit-control session (i.e., units associated to + Service-Identifier(s) or Rating-Group are granted), a new Credit- + Control-Request MUST be sent to the credit-control server when the + + + +Hakala, et al. Standards Track [Page 27] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + credit reservation has been wholly consumed, or upon expiration of + the Validity-Time. It is always up to the Diameter credit-control + client to send a new request well in advance of the expiration of the + previous request in order to avoid interruption in the service + element. Even if the granted service units reserved by the credit- + control server have not been spent upon expiration of the Validity- + Time, the Diameter credit-control client MUST send a new Credit- + Control-Request to the credit-control server. + + There can also be mid-session service events, which might affect the + rating of the current service events. In this case, a spontaneous + updating (a new Credit-Control-Request) SHOULD be sent including + information related to the service event even if all the granted + service units have not been spent or the Validity-Time has not + expired. + + When the used units are reported to the credit-control server, the + credit-control client will not have any units in its possession + before new granted units are received from the credit-control server. + When the new granted units are received, these units apply from the + point where the measurement of the reported used units stopped. + Where independent credit-control of multiple services is supported, + this process may be executed for one or more services, a single + rating-group, or a pool within the (sub)session. + + The CC-Request-Type AVP is set to the value UPDATE_REQUEST in the + intermediate request message. The Subscription-Id AVP SHOULD be + included in the intermediate message to identify the end user in the + credit-control server. The Service-Context-Id AVP indicates the + service specific document applicable to the request. + + The Requested-Service-Unit AVP MAY contain the new amount of + requested service units. Where the Multiple-Services-Credit-Control + AVP is used, it MUST contain the Requested-Service-Unit AVP if a new + quota is requested for the associated service/rating-group. The + Used-Service-Unit AVP contains the amount of used service units + measured from the point when the service became active or, if interim + interrogations are used during the session, from the point when the + previous measurement ended. The same unit types used in the previous + message SHOULD be used. If several unit types were included in the + previous answer message, the used service units for each unit type + MUST be reported. + + The Event-Timestamp AVP SHOULD be included in the request and + contains the time of the event that triggered the sending of the new + Credit-Control-Request. + + + + + +Hakala, et al. Standards Track [Page 28] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + The credit-control server MUST deduct the used amount from the end + user's account. It MAY rate the new request and make a new credit- + reservation from the end user's account that covers the cost of the + requested service event. + + A Credit-Control-Answer message with the CC-Request-Type AVP set to + the value UPDATE_REQUEST MAY include the Cost-Information AVP + containing the accumulated cost estimation for the session, without + taking any credit-reservation into account. + + The Credit-Control-Answer message MAY also include the Final-Unit- + Indication AVP to indicate that the answer message contains the final + units for the service. After the end user has consumed these units, + the Diameter credit-control-client MUST behave as described in + section 5.6. + + There can be several intermediate interrogations within a session. + +5.4. Final Interrogation + + When the end user terminates the service session, or when the + graceful service termination described in section 5.6 takes place, + the Diameter credit-control client MUST send a final Credit-Control- + Request message to the credit-control server. The CC-Request-Type + AVP is set to the value TERMINATION_REQUEST. The Service-Context-Id + AVP indicates the service specific document applicable to the + request. + + The Event-Timestamp AVP SHOULD be included in the request and + contains the time when the session was terminated. + + The Used-Service-Unit AVP contains the amount of used service units + measured from the point when the service became active or, if interim + interrogations are used during the session, from the point when the + previous measurement ended. If several unit types were included in + the previous answer message, the used service units for each unit + type MUST be reported. + + After final interrogation, the credit-control server MUST refund the + reserved credit amount not used to the end user's account and deduct + the used monetary amount from the end user's account. + + A Credit-Control-Answer message with the CC-Request-Type set to the + value TERMINATION_REQUEST MAY include the Cost-Information AVP + containing the estimated total cost for the session in question. + + If the user logs off during an ongoing credit-control session, or if + some other reason causes the user to become logged off (e.g., final- + + + +Hakala, et al. Standards Track [Page 29] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + unit indication causes user logoff according to local policy), the + service element, according to application specific policy, may send a + Session-Termination-Request (STR) to the home Diameter AAA server as + usual [DIAMBASE]. Figure 4 illustrates the case when the final-unit + indication causes user logoff upon consumption of the final granted + units and the generation of STR. + + Service Element AAA Server CC Server + End User (CC Client) + | Service Delivery | | | + |<----------------->| | | + | : | | | + | : | | | + | : | | | + | | | | + | | CCR(Update,Used-Units) | + | |------------------->| CCR(Update,Used-Units) + | | |------------------->| + | | CCA(Final-Unit, Terminate) + | CCA(Final-Unit, Terminate)|<-------------------| + | |<-------------------| | + | : | | | + | : | | | + | Disconnect user | | | + |<------------------| CCR(Termination,Used-Units) | + | |------------------->| CCR(Term.,Used-Units) + | | |------------------->| + | | | CCA | + | | CCA |<-------------------| + | |<-------------------| | + | | STR | | + | |------------------->| | + | | STA | | + | |<-------------------| | + + Figure 4: User disconnected due to exhausted account + +5.5. Server-Initiated Credit Re-Authorization + + The Diameter credit-control application supports server-initiated + re-authorization. The credit-control server MAY optionally initiate + the credit re-authorization by issuing a Re-Auth-Request (RAR) as + defined in the Diameter base protocol [DIAMBASE]. The Auth- + Application-Id in the RAR message is set to 4 to indicate Diameter + Credit Control, and the Re-Auth-Request-Type is set to + AUTHORIZE_ONLY. + + + + + +Hakala, et al. Standards Track [Page 30] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Section 5.1.2 defines the feature to enable credit-control for + multiple services within a single (sub-)session where the server can + authorize credit usage at a different level of granularity. Further, + the server may provide credit resources to multiple services or + rating groups as a pool (see section 5.1.2 for details and + definitions). Therefore, the server, based on its service logic and + its knowledge of the ongoing session, can decide to request credit + re-authorization for a whole (sub-)session, a single credit pool, a + single service, or a single rating-group. To request credit re- + authorization for a credit pool, the server includes in the RAR + message the G-S-U-Pool-Identifier AVP indicating the affected pool. + To request credit re-authorization for a service or a rating-group, + the server includes in the RAR message the Service-Identifier AVP or + the Rating-Group AVP, respectively. To request credit re- + authorization for all the ongoing services within the (sub-)session, + the server includes none of the above mentioned AVPs in the RAR + message. + + If a credit re-authorization is not already ongoing (i.e., the + credit-control session is in Open state), a credit control client + that receives an RAR message with Session-Id equal to a currently + active credit-control session MUST acknowledge the request by sending + the Re-Auth-Answer (RAA) message and MUST initiate the credit re- + authorization toward the server by sending a Credit-Control-Request + message with the CC-Request-Type AVP set to the value UPDATE_REQUEST. + The Result-Code 2002 (DIAMETER_LIMITED_SUCCESS) SHOULD be used in the + RAA message to indicate that an additional message (i.e., CCR message + with the value UPDATE_REQUEST) is required to complete the procedure. + If a quota was allocated to the service, the credit-control client + MUST report the used quota in the Credit-Control-Request. Note that + the end user does not need to be prompted for the credit re- + authorization, since the credit re-authorization is transparent to + the user (i.e., it takes place exclusively between the credit-control + client and the credit-control server). + + Where multiple services in a user's session are supported, the + procedure in the above paragraph will be executed at the granularity + requested by the server in the RAR message. + + If credit re-authorization is ongoing at the time when the RAR + message is received (i.e., RAR-CCR collision), the credit-control + client successfully acknowledges the request but does not initiate a + new credit re-authorization. The Result-Code 2001 (DIAMETER_SUCCESS) + SHOULD be used in the RAA message to indicate that a credit re- + authorization procedure is already ongoing (i.e., the client was in + PendingU state when the RAR was received). The credit-control server + SHOULD process the Credit-Control-Request as if it was received in + answer to the server initiated credit re-authorization, and should + + + +Hakala, et al. Standards Track [Page 31] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + consider the server initiated credit re-authorization process + successful upon reception of the Re-Auth-Answer message. + + When multiple services are supported in a user's session, the server + may request credit re-authorization for a credit pool (or for the + (sub-)session) while a credit re-authorization is already ongoing for + some of the services or rating-groups. In this case, the client + acknowledges the server request with an RAA message and MUST send a + new Credit-Control-Request message to perform re-authorization for + the remaining services/rating-groups. The Result-Code 2002 + (DIAMETER_LIMITED_SUCCESS) SHOULD be used in the RAA message to + indicate that an additional message (i.e., CCR message with value + UPDATE_REQUEST) is required to complete the procedure. The server + processes the received requests and returns an appropriate answer to + both requests. + + The above-defined procedures are enabled for each of the possibly + active Diameter credit-control sub-sessions. The server MAY request + re-authorization for an active sub-session by including the CC-Sub- + Session-Id AVP in the RAR message in addition to the Session-Id AVP. + +5.6. Graceful Service Termination + + When the user's account runs out of money, the user may not be + allowed to compile additional chargeable events. However, the home + service provider may offer some services; for instance, access to a + service portal where it is possible to refill the account, for which + the user is allowed to benefit for a limited time. The length of + this time is usually dependent on the home service provider policy. + + This section defines the optional graceful service termination + feature that MAY be supported by the credit-control server. Credit- + control client implementations MUST support the Final-Unit-Indication + with at least the teardown of the ongoing service session once the + subscriber has consumed all the final granted units. + + Where independent credit-control of multiple services in a single + credit-control (sub-)session is supported, it is possible to use the + graceful service termination for each of the services/rating-groups + independently. Naturally, the graceful service termination process + defined in the following sub-sections will apply to the specific + service/rating-group as requested by the server. + + In some service environments (e.g., NAS), the graceful service + termination may be used to redirect the subscriber to a service + portal for online balance refill or other services offered by the + home service provider. In this case, the graceful termination + process installs a set of packet filters to restrict the user's + + + +Hakala, et al. Standards Track [Page 32] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + access capability only to/from the specified destinations. All the + IP packets not matching the filters will be dropped or, possibly, + re-directed to the service portal. The user may also be sent an + appropriate notification as to why the access has been limited. + These actions may be communicated explicitly from the server to the + client or may be configured per-service at the client. Explicitly + signaled redirect or restrict instructions always take precedence + over configured ones. + + It is also possible use the graceful service termination to connect + the prepaid user to a top-up server that plays an announcement and + prompts the user to replenish the account. In this case, the + credit-control server sends only the address of the top-up server + where the prepaid user shall be connected after the final granted + units have been consumed. An example of this is given in Appendix A + (Flow VII). + + The credit-control server MAY initiate the graceful service + termination by including the Final-Unit-Indication AVP in the + Credit-Control-Answer to indicate that the message contains the final + units for the service. + + When the credit-control client receives the Final-Unit-Indication AVP + in the answer from the server, its behavior depends on the value + indicated in the Final-Unit-Action AVP. The server may request the + following actions: TERMINATE, REDIRECT, or RESTRICT_ACCESS. + + A following figure illustrates the graceful service termination + procedure described in the following sub-sections. + + + + + + + + + + + + + + + + + + + + + + +Hakala, et al. Standards Track [Page 33] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Diameter + End User Service Element AAA Server CC Server + (CC Client) + | Service Delivery | | | + |<----------------->| | | + | |CCR(Update,Used-Units) | + | |------------------->|CCR(Update,Used-Units) + | : | |------------------->| + | : | |CCA(Final-Unit,Action) + | : | |<-------------------| + | |CCA(Final-Unit,Action) | + | |<-------------------| | + | | | | + | : | | | + | : | | | + | : | | | + | /////////////// |CCR(Update,Used-Units) | + |/Final Units End/->|------------------->|CCR(Update,Used-Units) + |/Action and // | |------------------->| + |/Restrictions // | | CCA(Validity-Time)| + |/Start // | CCA(Validity-Time)|<-------------------| + | ///////////// |<-------------------| | + | : | | | + | : | | | + | Replenish Account +-------+ | + |<-------------------------------------------->|Account| | + | | | +-------+ | + | | | RAR | + | + | RAR |<===================| + | | |<===================| | + | | | RAA | | + | ///////////// | |===================>| RAA | + | /If supported / | | CCR(Update) |===================>| + | /by CC Server/ | |===================>| CCR(Update) | + | ///////////// | | |===================>| + | | | | CCA(Granted-Unit)| + | | | CCA(Granted-Unit)|<===================| + | Restrictions ->+ |<===================| | + | removed | | | + | : | | | + | OR | CCR(Update) | | + | Validity-Time ->|------------------->| CCR(Update) | + | expires | |------------------->| + | | | CCA(Granted-Unit)| + | | CCA(Granted-Unit)|<-------------------| + | Restrictions ->|<-------------------| | + | removed | | | + + + + +Hakala, et al. Standards Track [Page 34] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Figure 5: Optional graceful service termination procedure + +5.6.1. Terminate Action + + The Final-Unit-Indication AVP with Final-Unit-Action TERMINATE does + not include any other information. When the subscriber has consumed + the final granted units, the service element MUST terminate the + service. This is the default handling applicable whenever the + credit-control client receives an unsupported Final-Unit-Action value + and MUST be supported by all the Diameter credit-control client + implementations conforming to this specification. A final Credit- + Control-Request message to the credit-control server MUST be sent if + the Final-Unit-Indication AVP indicating action TERMINATE was present + at command level. The CC-Request-Type AVP in the request is set to + the value TERMINATION_REQUEST. + +5.6.2. Redirect Action + + The Final-Unit-Indication AVP with Final-Unit-Action REDIRECT + indicates to the service element supporting this action that, upon + consumption of the final granted units, the user MUST be re-directed + to the address specified in the Redirect-Server AVP as follows. + + The credit-control server sends the Redirect-Server AVP in the + Credit-Control-Answer message. In such a case, the service element + MUST redirect or connect the user to the destination specified in the + Redirect-Server AVP, if possible. When the end user is redirected + (by using protocols others than Diameter) to the specified server or + connected to the top-up server, an additional authorization (and + possibly authentication) may be needed before the subscriber can + replenish the account; however, this is out of the scope of this + specification. + + In addition to the Redirect-Server AVP, the credit-control server MAY + include one or more Restriction-Filter-Rule AVPs or one or more + Filter-Id AVPs in the Credit-Control-Answer message to enable the + user to access other services (for example, zero-rated services). In + such a case, the access device MUST drop all the packets not matching + the IP filters specified in the Credit-Control-Answer message and, if + possible, redirect the user to the destination specified in the + Redirect-Server AVP. + + An entity other than the credit-control server may provision the + access device with appropriate IP packet filters to be used in + conjunction with the Diameter credit-control application. This case + is considered in section 5.6.3. + + + + + +Hakala, et al. Standards Track [Page 35] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + When the final granted units have been consumed, the credit-control + client MUST perform an intermediate interrogation. The purpose of + this interrogation is to indicate to the credit-control server that + the specified action started and to report the used units. The + credit-control server MUST deduct the used amount from the end user's + account but MUST NOT make a new credit reservation. The credit- + control client, however, may send intermediate interrogations before + all the final granted units have been consumed for which rating and + money reservation may be needed; for instance, upon Validity-Time + expires or upon mid-session service events that affect the rating of + the current service. Therefore, the credit-control client MUST NOT + include any rating related AVP in the request sent once all the final + granted units have been consumed as an indication to the server that + the requested final unit action started, rating and money reservation + are not required (when the Multiple-Services-Credit-Control AVP is + used, the Service-Identifier or Rating-Group AVPs is included to + indicate the concerned services). Naturally, the Credit-Control- + Answer message does not contain any granted service unit and MUST + include the Validity-Time AVP to indicate to the credit-control + client how long the subscriber is allowed to use network resources + before a new intermediate interrogation is sent to the server. + + At the expiry of Validity-Time, the credit-control client sends a + Credit-Control-Request (UPDATE_REQUEST) as usual. This message does + not include the Used-Service-Unit AVP, as there is no allotted quota + to report. The credit-control server processes the request and MUST + perform the credit reservation. If during this time the subscriber + did not replenish his/her account, whether he/she will be + disconnected or will be granted access to services not controlled by + a credit-control server for an unlimited time is dependent on the + home service provider policy (note: the latter option implies that + the service element should not remove the restriction filters upon + termination of the credit-control). The server will return the + appropriate Result-Code (see section 9.1) in the Credit-Control- + Answer message in order to implement the policy-defined action. + Otherwise, new quota will be returned, the service element MUST + remove all the possible restrictions activated by the graceful + service termination process and continue the credit-control session + and service session as usual. + + The credit-control client may not wait until the expiration of the + Validity-Time and may send a spontaneous update (a new Credit- + Control-Request) if the service element can determine, for instance, + that communication between the end user and the top-up server took + place. An example of this is given in Appendix A (Figure A.8). + + + + + + +Hakala, et al. Standards Track [Page 36] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Note that the credit-control server may already have initiated the + above-described process for the first interrogation. However, the + user's account might be empty when this first interrogation is + performed. In this case, the subscriber can be offered a chance to + replenish the account and continue the service. The credit-control + client receives a Credit-Control-Answer or service specific + authorization answer with the Final-Unit-Indication and Validity-Time + AVPs but no Granted-Service-Unit. It immediately starts the graceful + service termination without sending any message to the server. An + example of this case is illustrated in Appendix A. + +5.6.3. Restrict Access Action + + A Final-Unit-Indication AVP with the Final-Unit-Action + RESTRICT_ACCESS indicates to the device supporting this action that + the user's access MUST be restricted according to the IP packet + filters given in the Restriction-Filter-Rule AVP(s) or according to + the IP packet filters identified by the Filter-Id AVP(s). The + credit-control server SHOULD include either the Restriction-Filter- + Rule AVP or the Filter-Id AVP in the Credit-Control-Answer message. + + An entity other than the credit-control server may provision the + access device with appropriate IP packet filters to be used in + conjunction with the Diameter credit-control application. Such an + entity may, for instance, configure the access device with IP flows + to be passed when the Diameter credit-control application indicates + RESTRICT_ACCESS or REDIRECT. The access device passes IP packets + according to the filter rules that may have been received in the + Credit-Control-Answer message in addition to those that may have been + configured by the other entity. However, when the user's account + cannot cover the cost of the requested service, the action taken is + the responsibility of the credit-control server that controls the + prepaid subscriber. + + If another entity working in conjunction with the Diameter credit- + control application already provisions the access device with all the + required filter rules for the end user, the credit-control server + presumably need not send any additional filter. Therefore, it is + RECOMMENDED that credit-control server implementations supporting the + graceful service termination be configurable for sending the + Restriction-Filter-Rule AVP, the Filter-Id AVP, or none of the above. + + When the final granted units have been consumed, the credit-control + client MUST perform an intermediate interrogation. The credit- + control client and the credit-control server process this + intermediate interrogation and execute subsequent procedures, as + specified in the previous section for the REDIRECT action. + + + + +Hakala, et al. Standards Track [Page 37] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + The credit-control server may initiate the graceful service + termination with action RESTRICT_ACCESS already for the first + interrogation, as specified in the previous section for the REDIRECT + action. + +5.6.4. Usage of the Server-Initiated Credit Re-Authorization + + Once the subscriber replenishes the account, she presumably expects + all the restrictions placed by the graceful termination procedure to + be removed immediately and unlimited service' access to be resumed. + For the best user experience, the credit-control server + implementation MAY support the server-initiated credit re- + authorization (see section 5.5). In such a case, upon the successful + account top-up, the credit-control server sends the Re-Auth-Request + (RAR) message to solicit the credit re-authorization. The credit- + control client initiates the credit re-authorization by sending the + Credit-Control-Request message with the CC-Request-Type AVP set to + the value UPDATE_REQUEST. The Used-Service-Unit AVP is not included + in the request, as there is no allotted quota to report. The + Requested-Service-Unit AVP MAY be included in the request. After the + credit-control client successfully receives the Credit-Control-Answer + with new Granted-Service-Unit, all the possible restrictions + activated for the purpose of the graceful service termination MUST be + removed in the service element. The credit-control session and the + service session continue as usual. + +5.7. Failure Procedures + + The Credit-Control-Failure-Handling AVP (CCFH), as described in this + section, determines the behavior of the credit-control client in + fault situations. The CCFH may be received from the Diameter home + AAA server, from the credit-control server, or may be configured + locally. The CCFH value received from the home AAA server overrides + the locally configured value. The CCFH value received from the + credit-control server in the Credit-Control-Answer message always + overrides any existing value. + + The authorization server MAY include the Accounting-Realtime-Required + AVP to determine what to do if the sending of accounting records to + the accounting server has been temporarily prevented, as defined in + [DIAMBASE]. It is RECOMMENDED that the client complement the + credit-control failure procedures with backup accounting flow toward + an accounting server. By using different combinations of + Accounting-Realtime-Required and Credit-Control-Failure-Handling + AVPs, different safety levels can be built. For example, by choosing + a Credit-Control-Failure-Handling AVP equal to CONTINUE for the + credit-control flow and a Accounting-Realtime-Required AVP equal to + DELIVER_AND_GRANT for the accounting flow, the service can be granted + + + +Hakala, et al. Standards Track [Page 38] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + to the end user even if the connection to the credit-control server + is down, as long as the accounting server is able to collect the + accounting information and information exchange is taking place + between the accounting server and credit-control server. + + As the credit-control application is based on real-time bi- + directional communication between the credit-control client and the + credit-control server, the usage of alternative destinations and the + buffering of messages may not be sufficient in the event of + communication failures. Because the credit-control server has to + maintain session states, moving the credit-control message stream to + a backup server requires a complex context transfer solution. + Whether the credit-control message stream is moved to a backup + credit-control server during an ongoing credit-control session + depends on the value of the CC-Session-Failover AVP. However, + failover may occur at any point in the path between the credit- + control client and the credit-control server if a transport failure + is detected with a peer, as described in [DIAMBASE]. As a + consequence, the credit-control server might receive duplicate + messages. These duplicates or out of sequence messages can be + detected in the credit-control server based on the credit-control + server session state machine (section 7), Session-Id AVP, and CC- + Request-Number AVP. + + If a failure occurs during an ongoing credit-control session, the + credit-control client may move the credit-control message stream to + an alternative server if the CC-server indicated FAILOVER_SUPPORTED + in the CC-Session-Failover AVP. A secondary credit-control server + name, either received from the home Diameter AAA server or configured + locally, can be used as an address of the backup server. If the CC- + Session-Failover AVP is set to FAILOVER_NOT_SUPPORTED, the credit- + control message stream MUST NOT be moved to a backup server. + + For new credit-control sessions, failover to an alternative credit- + control server SHOULD be performed if possible. For instance, if an + implementation of the credit-control client can determine primary + credit-control server unavailability, it can establish the new + credit-control sessions with a possibly available secondary credit- + control server. + + The AAA transport profile [AAATRANS] defines the application layer + watchdog algorithm that enables failover from a peer that has failed + and is controlled by a watchdog timer (Tw) defined in [AAATRANS]. + The recommended default initial value for Tw (Twinit) is 30 seconds. + Twinit may be set as low as 6 seconds; however, according to + [AAATRANS], setting too low a value for Twinit is likely to result in + an increased probability of duplicates, as well as an increase in + spurious failover and failback attempts. The Diameter base protocol + + + +Hakala, et al. Standards Track [Page 39] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + is common to several different types of Diameter AAA applications + that may be run in the same service element. Therefore, tuning the + timer Twinit to a lower value in order to satisfy the requirements of + real-time applications, such as the Diameter credit-control + application, will certainly cause the above mentioned problems. For + prepaid services, however, the end user expects an answer from the + network in a reasonable time. Thus, the Diameter credit-control + client will react faster than would the underlying base protocol. + Therefore this specification defines the timer Tx that is used by the + credit-control client (as defined in section 13) to supervise the + communication with the credit-control server. When the timer Tx + elapses, the credit-control client takes an action to the end user + according to the Credit-Control-Failure-Handling AVP. + + When Tx expires, the Diameter credit-control client always terminates + the service if the Credit-Control-Failure-Handling (CCFH) AVP is set + to the value TERMINATE. The credit-control session may be moved to + an alternative server only if a protocol error DIAMETER_TOO_BUSY or + DIAMETER_UNABLE_TO_DELIVER is received before Tx expires. Therefore, + the value TERMINATE is not appropriate if proper failover behavior is + desired. + + If the Credit-Control-Failure-Handling AVP is set to the value + CONTINUE or RETRY_AND_TERMINATE, the service will be granted to the + end user when the timer Tx expires. An answer message with granted- + units may arrive later if the base protocol transport failover + occurred in the path to the credit-control server. (The Twinit + default value is 3 times more than the Tx recommended value.) The + credit-control client SHOULD grant the service to the end user, start + monitoring the resource usage, and wait for the possible late answer + until the timeout of the request (e.g., 120 seconds). If the request + fails and the CC-Session-Failover AVP is set to + FAILOVER_NOT_SUPPORTED, the credit-control client terminates or + continues the service depending on the value set in the CCFH and MUST + free all the reserved resources for the credit-control session. If + the protocol error DIAMETER_UNABLE_TO_DELIVER or DIAMETER_TOO_BUSY is + received or the request times out and the CC-Session-Failover AVP is + set to FAILOVER_SUPPORTED, the credit-control client MAY send the + request to a backup server, if possible. If the credit-control + client receives a successful answer from the backup server, it + continues the credit-control session with such a server. If the re- + transmitted request also fails, the credit-control client terminates + or continues the service depending on the value set in the CCFH and + MUST free all the reserved resources for the credit-control session. + + If a communication failure occurs during the graceful service + termination procedure, the service element SHOULD always terminate + the ongoing service session. + + + +Hakala, et al. Standards Track [Page 40] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + If the credit-control server detects a failure during an ongoing + credit-control session, it will terminate the credit-control session + and return the reserved units back to the end user's account. + + The supervision session timer Tcc (as defined in section 13) is used + in the credit-control server to supervise the credit-control session. + + In order to support failover between credit-control servers, + information transfer about the credit-control session and account + state SHOULD take place between the primary and the secondary + credit-control server. Implementations supporting the credit-control + session failover MUST also ensure proper detection of duplicate or + out of sequence messages. The communication between the servers is + regarded as an implementation issue and is outside of the scope of + this specification. + +6. One Time Event + + The one-time event is used when there is no need to maintain any + state in the Diameter credit-control server; for example, enquiring + about the price of the service. The use of a one-time event implies + that the user has been authenticated and authorized beforehand. + + The one time event can be used when the credit-control client wants + to know the cost of the service event or to check the account balance + without any credit-reservation. It can also be used for refunding + service units on the user's account or for direct debiting without + any credit-reservation. The one time event is shown in Figure 6. + + Diameter + End User Service Element AAA Server CC Server + (CC Client) + | Service Request | | | + |------------------>| | | + | | CCR(Event) | | + | |------------------->| CCR(Event) | + | | |------------------->| + | | | CCA(Granted-Units)| + | | CCA(Granted-Units)|<-------------------| + | Service Delivery |<-------------------| | + |<----------------->| | | + + Figure 6: One time event + + In environments such as the 3GPP architecture, the one time event can + be sent from the service element directly to the credit-control + server. + + + + +Hakala, et al. Standards Track [Page 41] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +6.1. Service Price Enquiry + + The credit-control client may need to know the price of the service + event. Services offered by application service providers whose + prices are not known in the credit-control client might exist. The + end user might also want to get an estimation of the price of a + service event before requesting it. + + A Diameter credit-control client requesting the cost information MUST + set the CC-Request-Type AVP equal to EVENT_REQUEST, include the + Requested-Action AVP set to PRICE_ENQUIRY, and set the requested + service event information into the Service-Identifier AVP in the + Credit-Control-Request message. Additional service event information + may be sent as service specific AVPs or within the Service- + Parameter-Info AVP. The Service-Context-Id AVP indicates the service + specific document applicable to the request. + + The credit-control server calculates the cost of the requested + service event, but it does not perform any account balance check or + credit-reservation from the account. + + The estimated cost of the requested service event is returned to the + credit-control client in the Cost-Information AVP in the Credit- + Control-Answer message. + +6.2. Balance Check + + The Diameter credit-control client may only have to verify that the + end user's account balance covers the cost of a certain service + without reserving any units from the account at the time of the + inquiry. This method does not guarantee that credit would be left + when the Diameter credit-control client requests the debiting of the + account with a separate request. + + A Diameter credit-control client requesting the balance check MUST + set the CC-Request-Type AVP equal to EVENT_REQUEST, include a + Requested-Action AVP set to CHECK_BALANCE, and include the + Subscription-Id AVP in order to identify the end user in the credit- + control server. The Service-Context-Id AVP indicates the service + specific document applicable to the request. + + The credit-control server makes the balance check, but it does not + make any credit-reservation from the account. + + The result of balance check (ENOUGH_CREDIT/NO_CREDIT) is returned to + the credit-control client in the Check-Balance-Result AVP in the + Credit-Control-Answer message. + + + + +Hakala, et al. Standards Track [Page 42] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +6.3. Direct Debiting + + There are certain service events for which service execution is + always successful in the service environment. The delay between the + service invocation and the actual service delivery to the end user + can be sufficiently long that the use of the session-based credit- + control would lead to unreasonably long credit-control sessions. In + these cases, the Diameter credit-control client can use the one-time + event scenario for direct debiting. The Diameter credit-control + client SHOULD be sure that the requested service event execution + would be successful when this scenario is used. + + In the Credit-Control-Request message, the CC-Request-Type is set to + the value EVENT_REQUEST and the Requested-Action AVP is set to + DIRECT_DEBITING. The Subscription-Id AVP SHOULD be included to + identify the end user in the credit-control server. The Event- + Timestamp AVP SHOULD be included in the request and contain the time + when the service event is requested in the service element. The + Service-Context-Id AVP indicates the service specific document + applicable to the request. + + The Diameter credit-control client MAY include the monetary amount to + be charged in the Requested-Service-Unit AVP, if it knows the cost of + the service event. If the Diameter credit-control client does not + know the cost of the service event, the Requested-Service-Unit AVP + MAY contain the number of requested service events. The Service- + Identifier AVP always indicates the service concerned. Additional + service event information to be rated MAY be sent as service specific + AVPs or within the Service-Parameter-Info AVP. + + The credit-control server SHOULD rate the service event and deduct + the corresponding monetary amount from the end user's account. If + the type of the Requested-Service-Unit AVP is money, no rating is + needed, but the corresponding monetary amount is deducted from the + end user's account. + + The credit-control server returns the Granted-Service-Unit AVP in the + Credit-Control-Answer message to the Diameter credit-control client. + The Granted-Service-Unit AVP contains the amount of service units + that the Diameter credit-control client can provide to the end user. + The type of the Granted-Service-Unit can be time, volume, service + specific, or money, depending on the type of service event. + + If the credit-control server determines that no credit-control is + needed for the service, it can include the result code indicating + that the credit-control is not applicable (e.g., service is free of + charge). + + + + +Hakala, et al. Standards Track [Page 43] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + For informative purposes, the Credit-Control-Answer message MAY also + include the Cost-Information AVP containing the estimated total cost + of the requested service. + +6.4. Refund + + Some services may refund service units to the end user's account; for + example, gaming services. + + The credit-control client MUST set CC-Request-Type to the value + EVENT_REQUEST and the Requested-Action AVP to REFUND_ACCOUNT in the + Credit-Control-Request message. The Subscription-Id AVP SHOULD be + included to identify the end user in the credit-control server. The + Service-Context-Id AVP indicates the service specific document + applicable to the request. + + The Diameter credit-control client MAY include the monetary amount to + be refunded in the Requested-Service-Unit AVP. The Service- + Identifier AVP always indicates the concerned service. If the + Diameter credit-control client does not know the monetary amount to + be refunded, in addition to the Service-Identifier AVP it MAY send + service specific AVPs or the Service-Parameter-Info AVP containing + additional service event information to be rated. + + For informative purposes, the Credit-Control-Answer message MAY also + include the Cost-Information AVP containing the estimated monetary + amount of refunded unit. + +6.5. Failure Procedure + + Failover to an alternative credit-control server is allowed for a one + time event, as the server is not maintaining session states. For + instance, if the credit-control client receives a protocol error + DIAMETER_UNABLE_TO_DELIVER or DIAMETER_TOO_BUSY, it can re-send the + request to an alternative server, if possible. There MAY be protocol + transparent Diameter relays and redirect agents or Diameter credit- + control proxies between the credit-control client and credit-control + server. Failover may occur at any point in the path between the + credit-control client and the credit-control server if a transport + failure is detected with a peer, as described in [DIAMBASE]. Because + there can be duplicate requests for various reasons, the credit- + control server is responsible for real time duplicate detection. + Implementation issues for duplicate detection are discussed in + [DIAMBASE], Appendix C. + + When the credit-control client detects a communication failure with + the credit-control server, its behavior depends on the requested + action. The timer Tx (as defined in section 13) is used in the + + + +Hakala, et al. Standards Track [Page 44] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + credit-control client to supervise the communication with the + credit-control server. + + If the requested action is PRICE_ENQUIRY or CHECK_BALANCE and + communication failure is detected, the credit-control client SHOULD + forward the request messages to an alternative credit-control server, + if possible. The secondary credit-control server name, if received + from the home Diameter AAA server, can be used as an address of + backup server. + + If the requested action is DIRECT_DEBITING, the Direct-Debiting- + Failure-Handling AVP (DDFH) controls the credit-control client's + behavior. The DDFH may be received from the home Diameter AAA server + or may be locally configured. The credit-control server may also + send the DDFH in any CCA message to be used for direct debiting + events compiled thereafter. The DDFH value received from the home + Diameter AAA server overrides the locally configured value, and the + DDFH value received from the credit-control server in a Credit- + Control-Answer message always overrides any existing value. + + If the DDFH is set to TERMINATE_OR_BUFFER, the credit-control client + SHOULD NOT grant the service if it can determine, eventually after a + possible re-transmission attempt to an alternative credit-control + server, from the result code or error code in the answer message that + units have not been debited. Otherwise, the credit-control client + SHOULD grant the service to the end user and store the request in the + credit-control application level non-volatile storage. (Note that + re-sending the request at a later time is not a guarantee that the + service will be debited, as the user's account may be empty when the + server successfully processes the request.) The credit-control + client MUST mark these request messages as possible duplicates by + setting the T-flag in the command header as described in [DIAMBASE], + section 3. + + If the Direct-Debiting-Failure-Handling AVP is set to CONTINUE, the + service SHOULD be granted, even if credit-control messages cannot be + delivered and messages are not buffered. + + If the timer Tx expires, the credit-control client MUST continue the + service and wait for a possible late answer. If the request times + out, the credit-control client re-transmits the request (marked with + T-flag) to a backup credit-control server, if possible. If the re- + transmitted request also times out, or if a temporary error is + received in answer, the credit-control client buffers the request if + the value of the Direct-Debiting-Failure-Handling AVP is set to + TERMINATE_OR_BUFFER. If a failed answer is received for the + + + + + +Hakala, et al. Standards Track [Page 45] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + re-transmitted request, the credit-control client frees all the + resources reserved for the event message and deletes the request + regardless of the value of the DDFH. + + The Credit-Control-Request with the requested action REFUND_ACCOUNT + should always be stored in the credit-control application level non- + volatile storage in case of temporary failure. The credit-control + client MUST mark the re-transmitted request message as a possible + duplicate by setting the T-flag in the command header as described in + [DIAMBASE], section 3. + + For stored requests, the implementation may choose to limit the + number of re-transmission attempts and to define a re-transmission + interval. + + Note that only one place in the credit-control system SHOULD be + responsible for duplicate detection. If there is only one credit- + control server within the given realm, the credit-control server may + perform duplicate detection. If there is more than one credit- + control server in a given realm, only one entity in the credit- + control system should be responsible, to ensure that the end user's + account is not debited or credited multiple times for the same + service event. + +7. Credit-Control Application State Machine + + This section defines the credit-control application state machine. + + The first four state machines are to be observed by credit-control + clients. The first one describes the session-based credit-control + when the first interrogation is executed as part of the + authorization/authentication process. The second describes the + session-based credit-control when the first interrogation is executed + after the authorization/authentication process. The requirements as + to what state machines have to be supported are discussed in section + 5.2. + + The third state machine describes the session-based credit-control + for the intermediate and final interrogations. The fourth one + describes the event-based credit-control. These latter state + machines are to be observed by all implementations that conform to + this specification. + + The fifth state machine describes the credit-control session from a + credit-control server perspective. + + + + + + +Hakala, et al. Standards Track [Page 46] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Any event not listed in the state machines MUST be considered an + error condition, and a corresponding answer, if applicable, MUST be + returned to the originator of the message. + + In the state table, the event 'Failure to send' means that the + Diameter credit-control client is unable to communicate with the + desired destination or, if failover procedure is supported, with a + possibly defined alternative destination (e.g., the request times out + and the answer message is not received). This could be due to the + peer being down, or due to a physical link failure in the path to or + from the credit-control server. + + The event 'Temporary error' means that the Diameter credit-control + client received a protocol error notification (DIAMETER_TOO_BUSY, + DIAMETER_UNABLE_TO_DELIVER, or DIAMETER_LOOP_DETECTED) in the + Result-Code AVP of the Credit-Control-Answer command. The above + protocol error notification may ultimately be received in answer to + the re-transmitted request to a defined alternative destination, if + failover is supported. + + The event 'Failed answer' means that the Diameter credit-control + client received non-transient failure (permanent failure) + notification in the Credit-Control-Answer command. The above + permanent failure notification may ultimately be received in answer + to the re-transmitted request to a defined alternative destination, + if failover is supported. + + The action 'store request' means that a request is stored in the + credit-control application level non-volatile storage. + + The event 'Not successfully processed' means that the credit-control + server could not process the message; e.g., due to an unknown end + user, account being empty, or errors defined in [DIAMBASE]. + + The event 'User service terminated' can be triggered by various + reasons, e.g., normal user termination, network failure, and ASR + (Abort-Session-Request). The Termination-Cause AVP contains + information about the termination reason, as specified in [DIAMBASE]. + + The Tx timer, which is used to control the waiting time in the + credit-control client in the Pending state, is stopped upon exit of + the Pending state. The stopping of the Tx timer is omitted in the + state machine when the new state is Idle, as moving to Idle state + implies the clearing of the session and all the variables associated + to it. + + + + + + +Hakala, et al. Standards Track [Page 47] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + The states PendingI, PendingU, PendingT, PendingE, and PendingB stand + for pending states to wait for an answer to a credit-control request + related to Initial, Update, Termination, Event, or Buffered request, + respectively. + + The acronyms CCFH and DDFH stand for Credit-Control-Failure-Handling + and Direct-Debiting-Failure-Handling, respectively. + + In the following state machine table, the failover to a secondary + server upon 'Temporary error' or 'Failure to send' is not explicitly + described. Moving an ongoing credit-control message stream to an + alternative server is, however, possible if the CC-Session-Failover + AVP is set to FAILOVER_SUPPORTED, as described in section 5.7. + + Re-sending a credit-control event to an alternative server is + supported as described in section 6.5. + + CLIENT, SESSION BASED for the first interrogation with AA request + + State Event Action New State + --------------------------------------------------------------- + Idle Client or device requests Send PendingI + access/service AA request + with added + CC AVPs, + start Tx + + PendingI Successful AA req. Grant Open + answer received service to + end user, + stop Tx + + PendingI Tx expired Disconnect Idle + user/dev + + PendingI Failed AA answer received Disconnect Idle + user/dev + + PendingI AA answer Grant Idle + received with result code service + equal to CREDIT_CONTROL_ to end user + NOT_APPLICABLE + + PendingI User service terminated Queue PendingI + termination + event + + + + + +Hakala, et al. Standards Track [Page 48] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + PendingI Change in rating condition Queue PendingI + changed + rating + condition + event + + CLIENT, SESSION BASED for the first interrogation with CCR + + State Event Action New State + ---------------------------------------------------------------- + + + Idle Client or device requests Send PendingI + access/service CC initial + req., + start Tx + + PendingI Successful CC initial Stop Tx Open + answer received + + PendingI Failure to send, or Grant Idle + temporary error and service to + CCFH equal to CONTINUE end user + + PendingI Failure to send, or Terminate Idle + temporary error and end user's + CCFH equal to TERMINATE service + or to RETRY_AND_TERMINATE + + PendingI Tx expired and CCFH Terminate Idle + equal to TERMINATE end user's + service + + PendingI Tx expired and CCFH equal Grant PendingI + to CONTINUE or to service to + RETRY_AND_TERMINATE end user + + PendingI CC initial answer Terminate Idle + received with result code end user's + END_USER_SERVICE_DENIED or service + USER_UNKNOWN + + PendingI CC initial answer Grant Idle + received with result code service + equal to CREDIT_CONTROL_ to end user + NOT_APPLICABLE + + + + + +Hakala, et al. Standards Track [Page 49] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + PendingI Failed CC initial answer Grant Idle + received and CCFH equal to service to + CONTINUE end user + + PendingI Failed CC initial answer Terminate Idle + received and CCFH equal end user's + to TERMINATE or to service + RETRY_AND_TERMINATE + + PendingI User service terminated Queue PendingI + termination + event + + PendingI Change in rating condition Queue PendingI + changed + rating + condition + event + + CLIENT, SESSION BASED for intermediate and final interrogations + + State Event Action New State + ---------------------------------------------------------------- + + Open Granted unit elapses Send PendingU + and no final unit CC update + indication received req., + start Tx + + Open Granted unit elapses Terminate PendingT + and final unit action end user's + equal to TERMINATE service, send + received CC termination + req. + + Open Change in rating condition Send PendingU + in queue CC update + req., + Start Tx + + Open Service terminated in queue Send PendingT + CC termination + req. + + Open Change in rating condition Send PendingU + or Validity-Time elapses CC update + req., + Start Tx + + + +Hakala, et al. Standards Track [Page 50] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Open User service terminated Send PendingT + CC termination + req. + + Open RAR received Send RAA PendingU + followed by + CC update req., + start Tx + + PendingU Successful CC update Stop Tx Open + answer received + + PendingU Failure to send, or Grant Idle + temporary error and service to + CCFH equal to CONTINUE end user + + PendingU Failure to send, or Terminate Idle + temporary error and end user's + CCFH equal to TERMINATE service + or to RETRY_AND_TERMINATE + + PendingU Tx expired and CCFH Terminate Idle + equal to TERMINATE end user's + service + + PendingU Tx expired and CCFH equal Grant PendingU + to CONTINUE or to service to + RETRY_AND_TERMINATE end user + + PendingU CC update answer Terminate Idle + received with result code end user's + END_USER_SERVICE_DENIED service + + PendingU CC update answer Grant Idle + received with result code service + equal to CREDIT_CONTROL_ to end user + NOT_APPLICABLE + + PendingU Failed CC update Grant Idle + answer received and service to + CCFH equal to CONTINUE end user + + PendingU Failed CC update Terminate Idle + answer received and CCFH end user's + equal to TERMINATE or service + to RETRY_AND_TERMINATE + + + + + +Hakala, et al. Standards Track [Page 51] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + PendingU User service terminated Queue PendingU + termination + event + + PendingU Change in rating Queue PendingU + condition changed + rating + condition + event + + PendingU RAR received Send RAA PendingU + + PendingT Successful CC Idle + termination answer received + + PendingT Failure to send, temporary Idle + error, or failed answer + + PendingT Change in rating condition PendingT + + CLIENT, EVENT BASED + + State Event Action New State + ---------------------------------------------------------------- + Idle Client or device requests Send PendingE + a one-time service CC event + req., + Start Tx + + Idle Request in storage Send PendingB + stored + request + + PendingE Successful CC event Grant Idle + answer received service to + end user + + PendingE Failure to send, temporary Indicate Idle + error, failed CC event service + answer received, or error + Tx expired; requested + action CHECK_BALANCE or + PRICE_ENQUIRY + + PendingE CC event answer Terminate Idle + received with result code end user's + END_USER_SERVICE_DENIED or service + USER_UNKNOWN and Tx running + + + +Hakala, et al. Standards Track [Page 52] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + PendingE CC event answer Grant Idle + received with result code service + CREDIT_CONTROL_NOT_APPLICABLE; to end + requested action user + DIRECT_DEBITING + + PendingE Failure to send, temporary Grant Idle + error, or failed CC event service + answer received; requested to end + action DIRECT_DEBITING; user + DDFH equal to CONTINUE + + PendingE Failed CC event Terminate Idle + answer received or temporary end user's + error; requested action service + DIRECT_DEBITING; + DDFH equal to + TERMINATE_OR_BUFFER and + Tx running + + PendingE Tx expired; requested Grant PendingE + action DIRECT_DEBITING service + to end + user + + PendingE Failure to send; requested Store Idle + action DIRECT_DEBITING; request with + DDFH equal to T-flag + TERMINATE_OR_BUFFER + + PendingE Temporary error; requested Store Idle + action DIRECT_DEBITING; request + DDFH equal to + TERMINATE_OR_BUFFER; + Tx expired + + PendingE Failed answer or answer Idle + received with result code + END_USER_SERVICE DENIED or + USER_UNKNOWN; requested action + DIRECT_DEBITING; Tx expired + + PendingE Failed CC event answer Indicate Idle + received; requested service + action REFUND_ACCOUNT error and + delete request + + + + + +Hakala, et al. Standards Track [Page 53] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + PendingE Failure to send or Store Idle + Tx expired; requested request + action REFUND_ACCOUNT with T-flag + + PendingE Temporary error, Store Idle + and requested action request + REFUND_ACCOUNT + + PendingB Successful CC answer Delete Idle + received request + + PendingB Failed CC answer Delete Idle + received request + + PendingB Failure to send or Idle + temporary error + + SERVER, SESSION AND EVENT BASED + + State Event Action New State + ---------------------------------------------------------------- + + Idle CC initial request Send Open + received and successfully CC initial + processed answer, + reserve units, + start Tcc + + Idle CC initial request Send Idle + received but not CC initial + successfully processed answer with + Result-Code + != SUCCESS + + Idle CC event request Send Idle + received and successfully CC event + processed answer + + Idle CC event request Send Idle + received but not CC event + successfully processed answer with + Result-Code + != SUCCESS + + + + + + + + +Hakala, et al. Standards Track [Page 54] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Open CC update request Send CC Open + received and successfully update answer, + processed debit used + units, + reserve + new units, + restart Tcc + + Open CC update request Send Idle + received but not CC update + successfully processed answer with + Result-Code + != SUCCESS, + debit used + units + + Open CC termination request Send Idle + received and successfully CC termin. + processed answer, + Stop Tcc, + debit used + units + + Open CC termination request Send Idle + received but not CC termin. + successfully processed answer with + Result-Code + != SUCCESS, + debit used + units + + Open Session supervision timer Tcc Release Idle + expired reserved + units + +8. Credit-Control AVPs + + This section defines the credit-control AVPs that are specific to + Diameter credit-control application and that MAY be included in the + Diameter credit-control messages. + + The AVPs defined in this section MAY also be included in + authorization commands defined in authorization-specific + applications, such as [NASREQ] and [DIAMMIP], if the first + interrogation is performed as part of the + authorization/authentication process, as described in section 5.2. + + + + + +Hakala, et al. Standards Track [Page 55] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + The Diameter AVP rules are defined in the Diameter Base [DIAMBASE], + section 4. These AVP rules are observed in AVPs defined in this + section. + + The following table describes the Diameter AVPs defined in the + credit-control application, their AVP Code values, types, possible + flag values, and whether the AVP MAY be encrypted. The Diameter base + [DIAMBASE] specifies the AVP Flag rules for AVPs in section 4.5. + + +--------------------+ + | AVP Flag rules | + |----+-----+----+----|----+ + AVP Section | | |SHLD|MUST| | + Attribute Name Code Defined Data Type |MUST| MAY | NOT|NOT |Encr| + -----------------------------------------|----+-----+----+----|----| + CC-Correlation-Id 411 8.1 OctetString| | P,M | | V | Y | + CC-Input-Octets 412 8.24 Unsigned64 | M | P | | V | Y | + CC-Money 413 8.22 Grouped | M | P | | V | Y | + CC-Output-Octets 414 8.25 Unsigned64 | M | P | | V | Y | + CC-Request-Number 415 8.2 Unsigned32 | M | P | | V | Y | + CC-Request-Type 416 8.3 Enumerated | M | P | | V | Y | + CC-Service- 417 8.26 Unsigned64 | M | P | | V | Y | + Specific-Units | | | | | | + CC-Session- 418 8.4 Enumerated | M | P | | V | Y | + Failover | | | | | | + CC-Sub-Session-Id 419 8.5 Unsigned64 | M | P | | V | Y | + CC-Time 420 8.21 Unsigned32 | M | P | | V | Y | + CC-Total-Octets 421 8.23 Unsigned64 | M | P | | V | Y | + CC-Unit-Type 454 8.32 Enumerated | M | P | | V | Y | + Check-Balance- 422 8.6 Enumerated | M | P | | V | Y | + Result | | | | | | + Cost-Information 423 8.7 Grouped | M | P | | V | Y | + Cost-Unit 424 8.12 UTF8String | M | P | | V | Y | + Credit-Control 426 8.13 Enumerated | M | P | | V | Y | + Credit-Control- 427 8.14 Enumerated | M | P | | V | Y | + Failure-Handling | | | | | | + Currency-Code 425 8.11 Unsigned32 | M | P | | V | Y | + Direct-Debiting- 428 8.15 Enumerated | M | P | | V | Y | + Failure-Handling | | | | | | + Exponent 429 8.9 Integer32 | M | P | | V | Y | + Final-Unit-Action 449 8.35 Enumerated | M | P | | V | Y | + Final-Unit- 430 8.34 Grouped | M | P | | V | Y | + Indication | | | | | | + Granted-Service- 431 8.17 Grouped | M | P | | V | Y | + Unit | | | | | | + G-S-U-Pool- 453 8.31 Unsigned32 | M | P | | V | Y | + Identifier | | | | | | + + + + +Hakala, et al. Standards Track [Page 56] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + G-S-U-Pool- 457 8.30 Grouped | M | P | | V | Y | + Reference | | | | | | + Multiple-Services 456 8.16 Grouped | M | P | | V | Y | + -Credit-Control | | | | | | + Multiple-Services 455 8.40 Enumerated | M | P | | V | Y | + -Indicator | | | | | | + Rating-Group 432 8.29 Unsigned32 | M | P | | V | Y | + Redirect-Address 433 8.38 Enumerated | M | P | | V | Y | + -Type | | | | | | + Redirect-Server 434 8.37 Grouped | M | P | | V | Y | + Redirect-Server 435 8.39 UTF8String | M | P | | V | Y | + -Address | | | | | | + Requested-Action 436 8.41 Enumerated | M | P | | V | Y | + Requested-Service 437 8.18 Grouped | M | P | | V | Y | + -Unit | | | | | | + Restriction 438 8.36 IPFiltrRule| M | P | | V | Y | + -Filter-Rule | | | | | | + Service-Context 461 8.42 UTF8String | M | P | | V | Y | + -Id | | | | | | + Service- 439 8.28 Unsigned32 | M | P | | V | Y | + Identifier | | | | | | + Service-Parameter 440 8.43 Grouped | | P,M | | V | Y | + -Info | | | | | | + Service- 441 8.44 Unsigned32 | | P,M | | V | Y | + Parameter-Type | | | | | | + Service- 442 8.45 OctetString| | P,M | | V | Y | + Parameter-Value | | | | | | + Subscription-Id 443 8.46 Grouped | M | P | | V | Y | + Subscription-Id 444 8.48 UTF8String | M | P | | V | Y | + -Data | | | | | | + Subscription-Id 450 8.47 Enumerated | M | P | | V | Y | + -Type | | | | | | + Tariff-Change 452 8.27 Enumerated | M | P | | V | Y | + -Usage | | | | | | + Tariff-Time 451 8.20 Time | M | P | | V | Y | + -Change | | | | | | + Unit-Value 445 8.8 Grouped | M | P | | V | Y | + Used-Service-Unit 446 8.19 Grouped | M | P | | V | Y | + User-Equipment 458 8.49 Grouped | | P,M | | V | Y | + -Info | | | | | | + User-Equipment 459 8.50 Enumerated | | P,M | | V | Y | + -Info-Type | | | | | | + User-Equipment 460 8.51 OctetString| | P,M | | V | Y | + -Info-Value | | | | | | + Value-Digits 447 8.10 Integer64 | M | P | | V | Y | + Validity-Time 448 8.33 Unsigned32 | M | P | | V | Y | + + + + + +Hakala, et al. Standards Track [Page 57] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +8.1. CC-Correlation-Id AVP + + The CC-Correlation-Id AVP (AVP Code 411) is of type OctetString and + contains information to correlate credit-control requests generated + for different components of the service; e.g., transport and service + level. The one who allocates the Service-Context-Id (i.e., unique + identifier of a service specific document) is also responsible for + defining the content and encoding of the CC-Correlation-Id AVP. + +8.2. CC-Request-Number AVP + + The CC-Request-Number AVP (AVP Code 415) is of type Unsigned32 and + identifies this request within one session. As Session-Id AVPs are + globally unique, the combination of Session-Id and CC-Request-Number + AVPs is also globally unique and can be used in matching credit- + control messages with confirmations. An easy way to produce unique + numbers is to set the value to 0 for a credit-control request of type + INITIAL_REQUEST and EVENT_REQUEST and to set the value to 1 for the + first UPDATE_REQUEST, to 2 for the second, and so on until the value + for TERMINATION_REQUEST is one more than for the last UPDATE_REQUEST. + +8.3. CC-Request-Type AVP + + The CC-Request-Type AVP (AVP Code 416) is of type Enumerated and + contains the reason for sending the credit-control request message. + It MUST be present in all Credit-Control-Request messages. The + following values are defined for the CC-Request-Type AVP: + + INITIAL_REQUEST 1 + An Initial request is used to initiate a credit-control session, + and contains credit control information that is relevant to the + initiation. + + UPDATE_REQUEST 2 + An Update request contains credit-control information for an + existing credit-control session. Update credit-control requests + SHOULD be sent every time a credit-control re-authorization is + needed at the expiry of the allocated quota or validity time. + Further, additional service-specific events MAY trigger a + spontaneous Update request. + + TERMINATION_REQUEST 3 + A Termination request is sent to terminate a credit-control + session and contains credit-control information relevant to the + existing session. + + + + + + +Hakala, et al. Standards Track [Page 58] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + EVENT_REQUEST 4 + An Event request is used when there is no need to maintain any + credit-control session state in the credit-control server. This + request contains all information relevant to the service, and is + the only request of the service. The reason for the Event request + is further detailed in the Requested-Action AVP. The Requested- + Action AVP MUST be included in the Credit-Control-Request message + when CC-Request-Type is set to EVENT_REQUEST. + +8.4. CC-Session-Failover AVP + + The CC-Session-Failover AVP (AVP Code 418) is type of Enumerated and + contains information as to whether moving the credit-control message + stream to a backup server during an ongoing credit-control session is + supported. In communication failures, the credit-control message + streams can be moved to an alternative destination if the credit- + control server supports failover to an alternative server. The + secondary credit-control server name, if received from the home + Diameter AAA server, can be used as an address of the backup server. + An implementation is not required to support moving a credit-control + message stream to an alternative server, as this also requires moving + information related to the credit-control session to backup server. + + The following values are defined for the CC-Session-Failover AVP: + + FAILOVER_NOT_SUPPORTED 0 + When the CC-Session-Failover AVP is set to FAILOVER_NOT_SUPPORTED, + the credit-control message stream MUST NOT to be moved to an + alternative destination in the case of communication failure. + + This is the default behavior if the AVP isn't included in the + reply from the authorization or credit-control server. + + FAILOVER_SUPPORTED 1 + When the CC-Session-Failover AVP is set to FAILOVER_SUPPORTED, the + credit-control message stream SHOULD be moved to an alternative + destination in the case of communication failure. Moving the + credit-control message stream to a backup server MAY require that + information related to the credit-control session should also be + forwarded to alternative server. + +8.5. CC-Sub-Session-Id AVP + + The CC-Sub-Session-Id AVP (AVP Code 419) is of type Unsigned64 and + contains the credit-control sub-session identifier. The combination + of the Session-Id and this AVP MUST be unique per sub-session, and + + + + + +Hakala, et al. Standards Track [Page 59] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + the value of this AVP MUST be monotonically increased by one for all + new sub-sessions. The absence of this AVP implies that no sub- + sessions are in use. + +8.6. Check-Balance-Result AVP + + The Check Balance Result AVP (AVP Code 422) is of type Enumerated and + contains the result of the balance check. This AVP is applicable + only when the Requested-Action AVP indicates CHECK_BALANCE in the + Credit-Control-Request command. + + The following values are defined for the Check-Balance-Result AVP. + + ENOUGH_CREDIT 0 + There is enough credit in the account to cover the requested + service. + + NO_CREDIT 1 + There isn't enough credit in the account to cover the requested + service. + +8.7. Cost-Information AVP + + The Cost-Information AVP (AVP Code 423) is of type Grouped, and it is + used to return the cost information of a service, which the credit- + control client can transfer transparently to the end user. The + included Unit-Value AVP contains the cost estimate (always type of + money) of the service, in the case of price enquiry, or the + accumulated cost estimation, in the case of credit-control session. + + The Currency-Code specifies in which currency the cost was given. + The Cost-Unit specifies the unit when the service cost is a cost per + unit (e.g., cost for the service is $1 per minute). + + When the Requested-Action AVP with value PRICE_ENQUIRY is included in + the Credit-Control-Request command, the Cost-Information AVP sent in + the succeeding Credit-Control-Answer command contains the cost + estimation of the requested service, without any reservation being + made. + + The Cost-Information AVP included in the Credit-Control-Answer + command with the CC-Request-Type set to UPDATE_REQUEST contains the + accumulated cost estimation for the session, without taking any + credit reservation into account. + + + + + + + +Hakala, et al. Standards Track [Page 60] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + The Cost-Information AVP included in the Credit-Control-Answer + command with the CC-Request-Type set to EVENT_REQUEST or + TERMINATION_REQUEST contains the estimated total cost for the + requested service. + + It is defined as follows (per the grouped-avp-def of + RFC 3588 [DIAMBASE]): + + Cost-Information ::= < AVP Header: 423 > + { Unit-Value } + { Currency-Code } + [ Cost-Unit ] + +8.8. Unit-Value AVP + + Unit-Value AVP is of type Grouped (AVP Code 445) and specifies the + units as decimal value. The Unit-Value is a value with an exponent; + i.e., Unit-Value = Value-Digits AVP * 10^Exponent. This + representation avoids unwanted rounding off. For example, the value + of 2,3 is represented as Value-Digits = 23 and Exponent = -1. The + absence of the exponent part MUST be interpreted as an exponent equal + to zero. + + It is defined as follows (per the grouped-avp-def of + RFC 3588 [DIAMBASE]): + + Unit-Value ::= < AVP Header: 445 > + { Value-Digits } + [ Exponent ] + +8.9. Exponent AVP + + Exponent AVP is of type Integer32 (AVP Code 429) and contains the + exponent value to be applied for the Value-Digit AVP within the + Unit-Value AVP. + +8.10. Value-Digits AVP + + The Value-Digits AVP is of type Integer64 (AVP Code 447) and contains + the significant digits of the number. If decimal values are needed + to present the units, the scaling MUST be indicated with the related + Exponent AVP. For example, for the monetary amount $ 0.05 the value + of Value-Digits AVP MUST be set to 5, and the scaling MUST be + indicated with the Exponent AVP set to -2. + + + + + + + +Hakala, et al. Standards Track [Page 61] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +8.11. Currency-Code AVP + + The Currency-Code AVP (AVP Code 425) is of type Unsigned32 and + contains a currency code that specifies in which currency the values + of AVPs containing monetary units were given. It is specified by + using the numeric values defined in the ISO 4217 standard [ISO4217]. + +8.12. Cost-Unit AVP + + The Cost-Unit AVP (AVP Code 424) is of type UTF8String, and it is + used to display a human readable string to the end user. It + specifies the applicable unit to the Cost-Information when the + service cost is a cost per unit (e.g., cost of the service is $1 per + minute). The Cost-Unit can be minutes, hours, days, kilobytes, + megabytes, etc. + +8.13. Credit-Control AVP + + The Credit-Control AVP (AVP Code 426) is of type Enumerated and MUST + be included in AA requests when the service element has credit- + control capabilities. + + CREDIT_AUTHORIZATION 0 + If the home Diameter AAA server determines that the user has + prepaid subscription, this value indicates that the credit-control + server MUST be contacted to perform the first interrogation. The + value of the Credit-Control AVP MUST always be set to 0 in an AA + request sent to perform the first interrogation and to initiate a + new credit-control session. + + RE_AUTHORIZATION 1 + This value indicates to the Diameter AAA server that a credit- + control session is ongoing for the subscriber and that the + credit-control server MUST not be contacted. The Credit-Control + AVP set to the value of 1 is to be used only when the first + interrogation has been successfully performed and the credit- + control session is ongoing (i.e., re-authorization triggered by + Authorization-Lifetime). This value MUST NOT be used in an AA + request sent to perform the first interrogation. + +8.14. Credit-Control-Failure-Handling AVP + + The Credit-Control-Failure-Handling AVP (AVP Code 427) is of type + Enumerated. The credit-control client uses information in this AVP + to decide what to do if sending credit-control messages to the + credit-control server has been, for instance, temporarily prevented + due to a network problem. Depending on the service logic, the + credit-control server can order the client to terminate the service + + + +Hakala, et al. Standards Track [Page 62] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + immediately when there is a reason to believe that the service cannot + be charged, or to try failover to an alternative server, if possible. + Then the server could either terminate or grant the service, should + the alternative connection also fail. + + TERMINATE 0 + When the Credit-Control-Failure-Handling AVP is set to TERMINATE, + the service MUST only be granted for as long as there is a + connection to the credit-control server. If the credit-control + client does not receive any Credit-Control-Answer message within + the Tx timer (as defined in section 13), the credit-control + request is regarded as failed, and the end user's service session + is terminated. + + This is the default behavior if the AVP isn't included in the + reply from the authorization or credit-control server. + + CONTINUE 1 + When the Credit-Control-Failure-Handling AVP is set to CONTINUE, + the credit-control client SHOULD re-send the request to an + alternative server in the case of transport or temporary failures, + provided that a failover procedure is supported in the credit- + control server and the credit-control client, and that an + alternative server is available. Otherwise, the service SHOULD be + granted, even if credit-control messages can't be delivered. + + RETRY_AND_TERMINATE 2 + When the Credit-Control-Failure-Handling AVP is set to + RETRY_AND_TERMINATE, the credit-control client SHOULD re-send the + request to an alternative server in the case of transport or + temporary failures, provided that a failover procedure is + supported in the credit-control server and the credit-control + client, and that an alternative server is available. Otherwise, + the service SHOULD not be granted when the credit-control messages + can't be delivered. + +8.15. Direct-Debiting-Failure-Handling AVP + + The Direct-Debiting-Failure-Handling AVP (AVP Code 428) is of type + Enumerated. The credit-control client uses information in this AVP + to decide what to do if sending credit-control messages (Requested- + Action AVP set to DIRECT_DEBITING) to the credit-control server has + been, for instance, temporarily prevented due to a network problem. + + TERMINATE_OR_BUFFER 0 + When the Direct-Debiting-Failure-Handling AVP is set to + TERMINATE_OR_BUFFER, the service MUST be granted for as long as + there is a connection to the credit-control server. If the + + + +Hakala, et al. Standards Track [Page 63] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + credit-control client does not receive any Credit-Control-Answer + message within the Tx timer (as defined in section 13) the + credit-control request is regarded as failed. The client SHOULD + terminate the service if it can determine from the failed answer + that units have not been debited. Otherwise the credit-control + client SHOULD grant the service, store the request in application + level non-volatile storage, and try to re-send the request. These + requests MUST be marked as possible duplicates by setting the T- + flag in the command header as described in [DIAMBASE] section 3. + + This is the default behavior if the AVP isn't included in the + reply from the authorization server. + + CONTINUE 1 + When the Direct-Debiting-Failure-Handling AVP is set to CONTINUE, + the service SHOULD be granted, even if credit-control messages + can't be delivered, and the request should be deleted. + +8.16. Multiple-Services-Credit-Control AVP + + Multiple-Services-Credit-Control AVP (AVP Code 456) is of type + Grouped and contains the AVPs related to the independent credit- + control of multiple services feature. Note that each instance of + this AVP carries units related to one or more services or related to + a single rating group. + + The Service-Identifier and the Rating-Group AVPs are used to + associate the granted units to a given service or rating group. If + both the Service-Identifier and the Rating-Group AVPs are included, + the target of the service units is always the service(s) indicated by + the value of the Service-Identifier AVP(s). If only the Rating- + Group-Id AVP is present, the Multiple-Services-Credit-Control AVP + relates to all the services that belong to the specified rating + group. + + The G-S-U-Pool-Reference AVP allows the server to specify a G-S-U- + Pool-Identifier identifying a credit pool within which the units of + the specified type are considered pooled. If a G-S-U-Pool-Reference + AVP is present, then actual service units of the specified type MUST + also be present. For example, if the G-S-U-Pool-Reference AVP + specifies Unit-Type TIME, then the CC-Time AVP MUST be present. + + The Requested-Service-Unit AVP MAY contain the amount of requested + service units or the requested monetary value. It MUST be present in + the initial interrogation and within the intermediate interrogations + in which new quota is requested. If the credit-control client does + not include the Requested-Service-Unit AVP in a request command, + because for instance, it has determined that the end-user terminated + + + +Hakala, et al. Standards Track [Page 64] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + the service, the server MUST debit the used amount from the user's + account but MUST NOT return a new quota in the corresponding answer. + The Validity-Time, Result-Code, and Final-Unit-Indication AVPs MAY be + present in an answer command as defined in sections 5.1.2 and 5.6 for + the graceful service termination. + + When both the Tariff-Time-Change and Tariff-Change-Usage AVPs are + present, the server MUST include two separate instances of the + Multiple-Services-Credit-Control AVP with the Granted-Service-Unit + AVP associated to the same service-identifier and/or rating-group. + Where the two quotas are associated to the same pool or to different + pools, the credit pooling mechanism defined in section 5.1.2 applies. + The Tariff-Change-Usage AVP MUST NOT be included in request commands + to report used units before, and after tariff time change the Used- + Service-Unit AVP MUST be used. + + A server not implementing the independent credit-control of multiple + services functionality MUST treat the Multiple-Services-Credit- + Control AVP as an invalid AVP. + + The Multiple-Services-Control AVP is defined as follows (per the + grouped-avp-def of RFC 3588 [DIAMBASE]): + + Multiple-Services-Credit-Control ::= < AVP Header: 456 > + [ Granted-Service-Unit ] + [ Requested-Service-Unit ] + *[ Used-Service-Unit ] + [ Tariff-Change-Usage ] + *[ Service-Identifier ] + [ Rating-Group ] + *[ G-S-U-Pool-Reference ] + [ Validity-Time ] + [ Result-Code ] + [ Final-Unit-Indication ] + *[ AVP ] + +8.17. Granted-Service-Unit AVP + + Granted-Service-Unit AVP (AVP Code 431) is of type Grouped and + contains the amount of units that the Diameter credit-control client + can provide to the end user until the service must be released or the + new Credit-Control-Request must be sent. A client is not required to + implement all the unit types, and it must treat unknown or + unsupported unit types in the answer message as an incorrect CCA + answer. In this case, the client MUST terminate the credit-control + session and indicate in the Termination-Cause AVP reason + DIAMETER_BAD_ANSWER. + + + + +Hakala, et al. Standards Track [Page 65] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + The Granted-Service-Unit AVP is defined as follows (per the grouped- + avp-def of RFC 3588 [DIAMBASE]): + + Granted-Service-Unit ::= < AVP Header: 431 > + [ Tariff-Time-Change ] + [ CC-Time ] + [ CC-Money ] + [ CC-Total-Octets ] + [ CC-Input-Octets ] + [ CC-Output-Octets ] + [ CC-Service-Specific-Units ] + *[ AVP ] + +8.18. Requested-Service-Unit AVP + + The Requested-Service-Unit AVP (AVP Code 437) is of type Grouped and + contains the amount of requested units specified by the Diameter + credit-control client. A server is not required to implement all the + unit types, and it must treat unknown or unsupported unit types as + invalid AVPs. + + The Requested-Service-Unit AVP is defined as follows (per the + grouped-avp-def of RFC 3588 [DIAMBASE]): + + Requested-Service-Unit ::= < AVP Header: 437 > + [ CC-Time ] + [ CC-Money ] + [ CC-Total-Octets ] + [ CC-Input-Octets ] + [ CC-Output-Octets ] + [ CC-Service-Specific-Units ] + *[ AVP ] + +8.19. Used-Service-Unit AVP + + The Used-Service-Unit AVP is of type Grouped (AVP Code 446) and + contains the amount of used units measured from the point when the + service became active or, if interim interrogations are used during + the session, from the point when the previous measurement ended. + + + + + + + + + + + + +Hakala, et al. Standards Track [Page 66] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + The Used-Service-Unit AVP is defined as follows (per the grouped- + avp-def of RFC 3588 [DIAMBASE]): + + Used-Service-Unit ::= < AVP Header: 446 > + [ Tariff-Change-Usage ] + [ CC-Time ] + [ CC-Money ] + [ CC-Total-Octets ] + [ CC-Input-Octets ] + [ CC-Output-Octets ] + [ CC-Service-Specific-Units ] + *[ AVP ] + +8.20. Tariff-Time-Change AVP + + The Tariff-Time-Change AVP (AVP Code 451) is of type Time. It is + sent from the server to the client and includes the time in seconds + since January 1, 1900, 00:00 UTC, when the tariff of the service will + be changed. + + The tariff change mechanism is optional for the client and server, + and it is not used for time-based services defined in section 5. If + a client does not support the tariff time change mechanism, it MUST + treat Tariff-Time-Change AVP in the answer message as an incorrect + CCA answer. In this case, the client terminates the credit-control + session and indicates in the Termination-Cause AVP reason + DIAMETER_BAD_ANSWER. + + Omission of this AVP means that no tariff change is to be reported. + +8.21. CC-Time AVP + + The CC-Time AVP (AVP Code 420) is of type Unsigned32 and indicates + the length of the requested, granted, or used time in seconds. + +8.22. CC-Money AVP + + The CC-Money AVP (AVP Code 413) is of type Grouped and specifies the + monetary amount in the given currency. The Currency-Code AVP SHOULD + be included. It is defined as follows (per the grouped-avp-def of + RFC 3588 [DIAMBASE]): + + CC-Money ::= < AVP Header: 413 > + { Unit-Value } + [ Currency-Code ] + + + + + + +Hakala, et al. Standards Track [Page 67] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +8.23. CC-Total-Octets AVP + + The CC-Total-Octets AVP (AVP Code 421) is of type Unsigned64 and + contains the total number of requested, granted, or used octets + regardless of the direction (sent or received). + +8.24. CC-Input-Octets AVP + + The CC-Input-Octets AVP (AVP Code 412) is of type Unsigned64 and + contains the number of requested, granted, or used octets that can + be/have been received from the end user. + +8.25. CC-Output-Octets AVP + + The CC-Output-Octets AVP (AVP Code 414) is of type Unsigned64 and + contains the number of requested, granted, or used octets that can + be/have been sent to the end user. + +8.26. CC-Service-Specific-Units AVP + + The CC-Service-Specific-Units AVP (AVP Code 417) is of type + Unsigned64 and specifies the number of service-specific units (e.g., + number of events, points) given in a selected service. The service- + specific units always refer to the service identified in the + Service-Identifier AVP (or Rating-Group AVP when the Multiple- + Services-Credit-Control AVP is used). + +8.27. Tariff-Change-Usage AVP + + The Tariff-Change-Usage AVP (AVP Code 452) is of type Enumerated and + defines whether units are used before or after a tariff change, or + whether the units straddled a tariff change during the reporting + period. Omission of this AVP means that no tariff change has + occurred. + + In addition, when present in answer messages as part of the + Multiple-Services-Credit-Control AVP, this AVP defines whether units + are allocated to be used before or after a tariff change event. + + When the Tariff-Time-Change AVP is present, omission of this AVP in + answer messages means that the single quota mechanism applies. + + Tariff-Change-Usage can be one of the following: + + UNIT_BEFORE_TARIFF_CHANGE 0 + When present in the Multiple-Services-Credit-Control AVP, this + value indicates the amount of the units allocated for use before a + tariff change occurs. + + + +Hakala, et al. Standards Track [Page 68] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + When present in the Used-Service-Unit AVP, this value indicates + the amount of resource units used before a tariff change had + occurred. + + UNIT_AFTER_TARIFF_CHANGE 1 + When present in the Multiple-Services-Credit-Control AVP, this + value indicates the amount of the units allocated for use after a + tariff change occurs. + + When present in the Used-Service-Unit AVP, this value indicates + the amount of resource units used after tariff change had + occurred. + + UNIT_INDETERMINATE 2 + The used unit contains the amount of units that straddle the + tariff change (e.g., the metering process reports to the credit- + control client in blocks of n octets, and one block straddled the + tariff change). This value is to be used only in the Used- + Service-Unit AVP. + +8.28. Service-Identifier AVP + + The Service-Identifier AVP is of type Unsigned32 (AVP Code 439) and + contains the identifier of a service. The specific service the + request relates to is uniquely identified by the combination of + Service-Context-Id and Service-Identifier AVPs. + + A usage example of this AVP is illustrated in Appendix A (Flow IX). + +8.29. Rating-Group AVP + + The Rating-Group AVP is of type Unsigned32 (AVP Code 432) and + contains the identifier of a rating group. All the services subject + to the same rating type are part of the same rating group. The + specific rating group the request relates to is uniquely identified + by the combination of Service-Context-Id and Rating-Group AVPs. + + A usage example of this AVP is illustrated in Appendix A (Flow IX). + +8.30. G-S-U-Pool-Reference AVP + + The G-S-U-Pool-Reference AVP (AVP Code 457) is of type Grouped. It + is used in the Credit-Control-Answer message, and associates the + Granted-Service-Unit AVP within which it appears with a credit pool + within the session. + + The G-S-U-Pool-Identifier AVP specifies the credit pool from which + credit is drawn for this unit type. + + + +Hakala, et al. Standards Track [Page 69] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + The CC-Unit-Type AVP specifies the type of units for which credit is + pooled. + + The Unit-Value AVP specifies the multiplier, which converts between + service units of type CC-Unit-Type and abstract service units within + the credit pool (and thus to service units of any other service or + rating group associated with the same pool). + + The G-S-U-Pool-Reference AVP is defined as follows (per the grouped- + avp-def of RFC 3588 [DIAMBASE]): + + G-S-U-Pool-Reference ::= < AVP Header: 457 > + { G-S-U-Pool-Identifier } + { CC-Unit-Type } + { Unit-Value } + +8.31. G-S-U-Pool-Identifier AVP + + The G-S-U-Pool-Identifier AVP (AVP Code 453) is of type Unsigned32 + and identifies a credit pool within the session. + +8.32. CC-Unit-Type AVP + + The CC-Unit-Type AVP (AVP Code 454) is of type Enumerated and + specifies the type of units considered to be pooled into a credit + pool. + + The following values are defined for the CC-Unit-Type AVP: + + TIME 0 + MONEY 1 + TOTAL-OCTETS 2 + INPUT-OCTETS 3 + OUTPUT-OCTETS 4 + SERVICE-SPECIFIC-UNITS 5 + +8.33. Validity-Time AVP + + The Validity-Time AVP is of type Unsigned32 (AVP Code 448). It is + sent from the credit-control server to the credit-control client. + The AVP contains the validity time of the granted service units. The + measurement of the Validity-Time is started upon receipt of the + Credit-Control-Answer Message containing this AVP. If the granted + service units have not been consumed within the validity time + specified in this AVP, the credit-control client MUST send a Credit- + Control-Request message to the server, with CC-Request-Type set to + UPDATE_REQUEST. The value field of the Validity-Time AVP is given in + seconds. + + + +Hakala, et al. Standards Track [Page 70] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + The Validity-Time AVP is also used for the graceful service + termination (see section 5.6) to indicate to the credit-control + client how long the subscriber is allowed to use network resources + after the specified action (i.e., REDIRECT or RESTRICT_ACCESS) + started. When the Validity-Time elapses, a new intermediate + interrogation is sent to the server. + +8.34. Final-Unit-Indication AVP + + The Final-Unit-Indication AVP (AVP Code 430) is of type Grouped and + indicates that the Granted-Service-Unit AVP in the Credit-Control- + Answer, or in the AA answer, contains the final units for the + service. After these units have expired, the Diameter credit-control + client is responsible for executing the action indicated in the + Final-Unit-Action AVP (see section 5.6). + + If more than one unit type is received in the Credit-Control-Answer, + the unit type that first expired SHOULD cause the credit-control + client to execute the specified action. + + In the first interrogation, the Final-Unit-Indication AVP with + Final-Unit-Action REDIRECT or RESTRICT_ACCESS can also be present + with no Granted-Service-Unit AVP in the Credit-Control-Answer or in + the AA answer. This indicates to the Diameter credit-control client + to execute the specified action immediately. If the home service + provider policy is to terminate the service, naturally, the server + SHOULD return the appropriate transient failure (see section 9.1) in + order to implement the policy-defined action. + + The Final-Unit-Action AVP defines the behavior of the service element + when the user's account cannot cover the cost of the service and MUST + always be present if the Final-Unit-Indication AVP is included in a + command. + + If the Final-Unit-Action AVP is set to TERMINATE, no other AVPs MUST + be present. + + If the Final-Unit-Action AVP is set to REDIRECT at least the + Redirect-Server AVP MUST be present. The Restriction-Filter-Rule AVP + or the Filter-Id AVP MAY be present in the Credit-Control-Answer + message if the user is also allowed to access other services that are + not accessible through the address given in the Redirect-Server AVP. + + If the Final-Unit-Action AVP is set to RESTRICT_ACCESS, either the + Restriction-Filter-Rule AVP or the Filter-Id AVP SHOULD be present. + + + + + + +Hakala, et al. Standards Track [Page 71] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + The Filter-Id AVP is defined in [NASREQ]. The Filter-Id AVP can be + used to reference an IP filter list installed in the access device by + means other than the Diameter credit-control application, e.g., + locally configured or configured by another entity. + + The Final-Unit-Indication AVP is defined as follows (per the + grouped-avp-def of RFC 3588 [DIAMBASE]): + + Final-Unit-Indication ::= < AVP Header: 430 > + { Final-Unit-Action } + *[ Restriction-Filter-Rule ] + *[ Filter-Id ] + [ Redirect-Server ] + +8.35. Final-Unit-Action AVP + + The Final-Unit-Action AVP (AVP Code 449) is of type Enumerated and + indicates to the credit-control client the action to be taken when + the user's account cannot cover the service cost. + + The Final-Unit-Action can be one of the following: + + TERMINATE 0 + The credit-control client MUST terminate the service session. + This is the default handling, applicable whenever the credit- + control client receives an unsupported Final-Unit-Action value, + and it MUST be supported by all the Diameter credit-control client + implementations conforming to this specification. + + REDIRECT 1 + The service element MUST redirect the user to the address + specified in the Redirect-Server-Address AVP. The redirect action + is defined in section 5.6.2. + + RESTRICT_ACCESS 2 + The access device MUST restrict the user access according to the + IP packet filters defined in the Restriction-Filter-Rule AVP or + according to the IP packet filters identified by the Filter-Id + AVP. All the packets not matching the filters MUST be dropped + (see section 5.6.3). + +8.36. Restriction-Filter-Rule AVP + + The Restriction-Filter-Rule AVP (AVP Code 438) is of type + IPFilterRule and provides filter rules corresponding to services that + are to remain accessible even if there are no more service units + granted. The access device has to configure the specified filter + + + + +Hakala, et al. Standards Track [Page 72] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + rules for the subscriber and MUST drop all the packets not matching + these filters. Zero, one, or more such AVPs MAY be present in a + Credit-Control-Answer message or in an AA answer message. + +8.37. Redirect-Server AVP + + The Redirect-Server AVP (AVP Code 434) is of type Grouped and + contains the address information of the redirect server (e.g., HTTP + redirect server, SIP Server) with which the end user is to be + connected when the account cannot cover the service cost. It MUST be + present when the Final-Unit-Action AVP is set to REDIRECT. + + It is defined as follows (per the grouped-avp-def of RFC 3588 + [DIAMBASE]): + + Redirect-Server ::= < AVP Header: 434 > + { Redirect-Address-Type } + { Redirect-Server-Address } + +8.38. Redirect-Address-Type AVP + + The Redirect-Address-Type AVP (AVP Code 433) is of type Enumerated + and defines the address type of the address given in the Redirect- + Server-Address AVP. + + The address type can be one of the following: + + IPv4 Address 0 + The address type is in the form of "dotted-decimal" IPv4 address, + as defined in [IPv4]. + + IPv6 Address 1 + The address type is in the form of IPv6 address, as defined in + [IPv6Addr]. The address is a text representation of the address + in either the preferred or alternate text form [IPv6Addr]. + Conformant implementations MUST support the preferred form and + SHOULD support the alternate text form for IPv6 addresses. + + URL 2 + The address type is in the form of Uniform Resource Locator, as + defined in [URL]. + + SIP URI 3 + The address type is in the form of SIP Uniform Resource + Identifier, as defined in [SIP]. + + + + + + +Hakala, et al. Standards Track [Page 73] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +8.39. Redirect-Server-Address AVP + + The Redirect-Server-Address AVP (AVP Code 435) is of type UTF8String + and defines the address of the redirect server (e.g., HTTP redirect + server, SIP Server) with which the end user is to be connected when + the account cannot cover the service cost. + +8.40. Multiple-Services-Indicator AVP + + The Multiple-Services-Indicator AVP (AVP Code 455) is of type + Enumerated and indicates whether the Diameter credit-control client + is capable of handling multiple services independently within a + (sub-) session. The absence of this AVP means that independent + credit-control of multiple services is not supported. + + A server not implementing the independent credit-control of multiple + services MUST treat the Multiple-Services-Indicator AVP as an invalid + AVP. + + The following values are defined for the Multiple-Services-Indicator + AVP: + + MULTIPLE_SERVICES_NOT_SUPPORTED 0 + Client does not support independent credit-control of multiple + services within a (sub-)session. + + MULTIPLE_SERVICES_SUPPORTED 1 + Client supports independent credit-control of multiple services + within a (sub-)session. + +8.41. Requested-Action AVP + + The Requested-Action AVP (AVP Code 436) is of type Enumerated and + contains the requested action being sent by Credit-Control-Request + command where the CC-Request-Type is set to EVENT_REQUEST. The + following values are defined for the Requested-Action AVP: + + DIRECT_DEBITING 0 + This indicates a request to decrease the end user's account + according to information specified in the Requested-Service-Unit + AVP and/or Service-Identifier AVP (additional rating information + may be included in service-specific AVPs or in the Service- + Parameter-Info AVP). The Granted-Service-Unit AVP in the Credit- + Control-Answer command contains the debited units. + + + + + + + +Hakala, et al. Standards Track [Page 74] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + REFUND_ACCOUNT 1 + This indicates a request to increase the end user's account + according to information specified in the Requested-Service-Unit + AVP and/or Service-Identifier AVP (additional rating information + may be included in service-specific AVPs or in the Service- + Parameter-Info AVP). The Granted-Service-Unit AVP in the Credit- + Control-Answer command contains the refunded units. + + CHECK_BALANCE 2 + This indicates a balance check request. In this case, the + checking of the account balance is done without any credit + reservation from the account. The Check-Balance-Result AVP in the + Credit-Control-Answer command contains the result of the balance + check. + + PRICE_ENQUIRY 3 + This indicates a price enquiry request. In this case, neither + checking of the account balance nor reservation from the account + will be done; only the price of the service will be returned in + the Cost-Information AVP in the Credit-Control-Answer Command. + +8.42. Service-Context-Id AVP + + The Service-Context-Id AVP is of type UTF8String (AVP Code 461) and + contains a unique identifier of the Diameter credit-control service + specific document that applies to the request (as defined in section + 4.1.2). This is an identifier allocated by the service provider, by + the service element manufacturer, or by a standardization body, and + MUST uniquely identify a given Diameter credit-control service + specific document. The format of the Service-Context-Id is: + + "service-context" "@" "domain" + + service-context = Token + + The Token is an arbitrary string of characters and digits. + + 'domain' represents the entity that allocated the Service-Context-Id. + It can be ietf.org, 3gpp.org, etc., if the identifier is allocated by + a standardization body, or it can be the FQDN of the service provider + (e.g., provider.example.com) or of the vendor (e.g., + vendor.example.com) if the identifier is allocated by a private + entity. + + This AVP SHOULD be placed as close to the Diameter header as + possible. + + + + + +Hakala, et al. Standards Track [Page 75] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Service-specific documents that are for private use only (i.e., to + one provider's own use, where no interoperability is deemed useful) + may define private identifiers without need of coordination. + However, when interoperability is wanted, coordination of the + identifiers via, for example, publication of an informational RFC is + RECOMMENDED in order to make Service-Context-Id globally available. + +8.43. Service-Parameter-Info AVP + + The Service-Parameter-Info AVP (AVP Code 440) is of type Grouped and + contains service-specific information used for price calculation or + rating. The Service-Parameter-Type AVP defines the service parameter + type, and the Service-Parameter-Value AVP contains the parameter + value. The actual contents of these AVPs are not within the scope of + this document and SHOULD be defined in another Diameter application, + in standards written by other standardization bodies, or in service- + specific documentation. + + In the case of an unknown service request (e.g., unknown Service- + Parameter-Type), the corresponding answer message MUST contain the + error code DIAMETER_RATING_FAILED. A Credit-Control-Answer message + with this error MUST contain one or more Failed-AVP AVPs containing + the Service-Parameter-Info AVPs that caused the failure. + + It is defined as follows (per the grouped-avp-def of RFC 3588 + [DIAMBASE]): + + Service-Parameter-Info ::= < AVP Header: 440 > + { Service-Parameter-Type } + { Service-Parameter-Value } + +8.44. Service-Parameter-Type AVP + + The Service-Parameter-Type AVP is of type Unsigned32 (AVP Code 441) + and defines the type of the service event specific parameter (e.g., + it can be the end-user location or service name). The different + parameters and their types are service specific, and the meanings of + these parameters are not defined in this document. Whoever allocates + the Service-Context-Id (i.e., unique identifier of a service-specific + document) is also responsible for assigning Service-Parameter-Type + values for the service and ensuring their uniqueness within the given + service. The Service-Parameter-Value AVP contains the value + associated with the service parameter type. + + + + + + + + +Hakala, et al. Standards Track [Page 76] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +8.45. Service-Parameter-Value AVP + + The Service-Parameter-Value AVP is of type OctetString (AVP Code 442) + and contains the value of the service parameter type. + +8.46. Subscription-Id AVP + + The Subscription-Id AVP (AVP Code 443) is used to identify the end + user's subscription and is of type Grouped. The Subscription-Id AVP + includes a Subscription-Id-Data AVP that holds the identifier and a + Subscription-Id-Type AVP that defines the identifier type. + + It is defined as follows (per the grouped-avp-def of RFC 3588 + [DIAMBASE]): + + Subscription-Id ::= < AVP Header: 443 > + { Subscription-Id-Type } + { Subscription-Id-Data } + +8.47. Subscription-Id-Type AVP + + The Subscription-Id-Type AVP (AVP Code 450) is of type Enumerated, + and it is used to determine which type of identifier is carried by + the Subscription-Id AVP. + + This specification defines the following subscription identifiers. + However, new Subscription-Id-Type values can be assigned by an IANA + designated expert, as defined in section 12. A server MUST implement + all the Subscription-Id-Types required to perform credit + authorization for the services it supports, including possible future + values. Unknown or unsupported Subscription-Id-Types MUST be treated + according to the 'M' flag rule, as defined in [DIAMBASE]. + + END_USER_E164 0 + The identifier is in international E.164 format (e.g., MSISDN), + according to the ITU-T E.164 numbering plan defined in [E164] and + [CE164]. + + END_USER_IMSI 1 + The identifier is in international IMSI format, according to the + ITU-T E.212 numbering plan as defined in [E212] and [CE212]. + + END_USER_SIP_URI 2 + The identifier is in the form of a SIP URI, as defined in [SIP]. + + END_USER_NAI 3 + The identifier is in the form of a Network Access Identifier, as + defined in [NAI]. + + + +Hakala, et al. Standards Track [Page 77] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + END_USER_PRIVATE 4 + The Identifier is a credit-control server private identifier. + +8.48. Subscription-Id-Data AVP + + The Subscription-Id-Data AVP (AVP Code 444) is used to identify the + end user and is of type UTF8String. The Subscription-Id-Type AVP + defines which type of identifier is used. + +8.49. User-Equipment-Info AVP + + The User-Equipment-Info AVP (AVP Code 458) is of type Grouped and + allows the credit-control client to indicate the identity and + capability of the terminal the subscriber is using for the connection + to network. + + It is defined as follows (per the grouped-avp-def of RFC 3588 + [DIAMBASE]): + + User-Equipment-Info ::= < AVP Header: 458 > + { User-Equipment-Info-Type } + { User-Equipment-Info-Value } + +8.50. User-Equipment-Info-Type AVP + + The User-Equipment-Info-Type AVP is of type Enumerated (AVP Code + 459) and defines the type of user equipment information contained in + the User-Equipment-Info-Value AVP. + + This specification defines the following user equipment types. + However, new User-Equipment-Info-Type values can be assigned by an + IANA designated expert, as defined in section 12. + + IMEISV 0 + The identifier contains the International Mobile Equipment + Identifier and Software Version in the international IMEISV format + according to 3GPP TS 23.003 [3GPPIMEI]. + + MAC 1 + The 48-bit MAC address is formatted as described in [RAD802.1X]. + + EUI64 2 + The 64-bit identifier used to identify hardware instance of the + product, as defined in [EUI64]. + + + + + + + +Hakala, et al. Standards Track [Page 78] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + MODIFIED_EUI64 3 + There are a number of types of terminals that have identifiers + other than IMEI, IEEE 802 MACs, or EUI-64. These identifiers can + be converted to modified EUI-64 format as described in [IPv6Addr] + or by using some other methods referred to in the service-specific + documentation. + +8.51. User-Equipment-Info-Value AVP + + The User-Equipment-Info-Value AVP (AVP Code 460) is of type + OctetString. The User-Equipment-Info-Type AVP defines which type of + identifier is used. + +9. Result Code AVP Values + + This section defines new Result-Code AVP [DIAMBASE] values that must + be supported by all Diameter implementations that conform to this + specification. + + The Credit-Control-Answer message includes the Result-Code AVP, which + may indicate that an error was present in the Credit-Control-Request + message. A rejected Credit-Control-Request message SHOULD cause the + user's session to be terminated. + +9.1. Transient Failures + + Errors that fall within the transient failures category are used to + inform a peer that the request could not be satisfied at the time it + was received, but that the request MAY be able to be satisfied in the + future. + + DIAMETER_END_USER_SERVICE_DENIED 4010 + The credit-control server denies the service request due to + service restrictions. If the CCR contained used-service-units, + they are deducted, if possible. + + DIAMETER_CREDIT_CONTROL_NOT_APPLICABLE 4011 + The credit-control server determines that the service can be + granted to the end user but that no further credit-control is + needed for the service (e.g., service is free of charge). + + DIAMETER_CREDIT_LIMIT_REACHED 4012 + The credit-control server denies the service request because the + end user's account could not cover the requested service. If the + CCR contained used-service-units they are deducted, if possible. + + + + + + +Hakala, et al. Standards Track [Page 79] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +9.2. Permanent Failures + + Errors that fall within the permanent failure category are used to + inform the peer that the request failed and should not be attempted + again. + + DIAMETER_USER_UNKNOWN 5030 + The specified end user is unknown in the credit-control server. + + DIAMETER_RATING_FAILED 5031 + This error code is used to inform the credit-control client that + the credit-control server cannot rate the service request due to + insufficient rating input, an incorrect AVP combination, or an AVP + or an AVP value that is not recognized or supported in the rating. + The Failed-AVP AVP MUST be included and contain a copy of the + entire AVP(s) that could not be processed successfully or an + example of the missing AVP complete with the Vendor-Id if + applicable. The value field of the missing AVP should be of + correct minimum length and contain zeros. + +10. AVP Occurrence Table + + The following table presents the AVPs defined in this document and + specifies in which Diameter messages they MAY or MAY NOT be present. + Note that AVPs that can only be present within a Grouped AVP are not + represented in this table. + + The table uses the following symbols: + + 0 The AVP MUST NOT be present in the message. + 0+ Zero or more instances of the AVP MAY be present in the + message. + 0-1 Zero or one instance of the AVP MAY be present in the + message. It is considered an error if there is more + than one instance of the AVP. + 1 One instance of the AVP MUST be present in the message. + 1+ At least one instance of the AVP MUST be present in the + message. + + + + + + + + + + + + + +Hakala, et al. Standards Track [Page 80] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +10.1. Credit-Control AVP Table + + The table in this section is used to represent which credit-control + applications specific AVPs defined in this document are to be present + in the credit-control messages. + + +-----------+ + | Command | + | Code | + |-----+-----+ + Attribute Name | CCR | CCA | + ------------------------------|-----+-----+ + Acct-Multi-Session-Id | 0-1 | 0-1 | + Auth-Application-Id | 1 | 1 | + CC-Correlation-Id | 0-1 | 0 | + CC-Session-Failover | 0 | 0-1 | + CC-Request-Number | 1 | 1 | + CC-Request-Type | 1 | 1 | + CC-Sub-Session-Id | 0-1 | 0-1 | + Check-Balance-Result | 0 | 0-1 | + Cost-Information | 0 | 0-1 | + Credit-Control-Failure- | 0 | 0-1 | + Handling | | | + Destination-Host | 0-1 | 0 | + Destination-Realm | 1 | 0 | + Direct-Debiting-Failure- | 0 | 0-1 | + Handling | | | + Event-Timestamp | 0-1 | 0-1 | + Failed-AVP | 0 | 0+ | + Final-Unit-Indication | 0 | 0-1 | + Granted-Service-Unit | 0 | 0-1 | + Multiple-Services-Credit- | 0+ | 0+ | + Control | | | + Multiple-Services-Indicator | 0-1 | 0 | + Origin-Host | 1 | 1 | + Origin-Realm | 1 | 1 | + Origin-State-Id | 0-1 | 0-1 | + Proxy-Info | 0+ | 0+ | + Redirect-Host | 0 | 0+ | + Redirect-Host-Usage | 0 | 0-1 | + Redirect-Max-Cache-Time | 0 | 0-1 | + Requested-Action | 0-1 | 0 | + Requested-Service-Unit | 0-1 | 0 | + Route-Record | 0+ | 0+ | + Result-Code | 0 | 1 | + Service-Context-Id | 1 | 0 | + Service-Identifier | 0-1 | 0 | + Service-Parameter-Info | 0+ | 0 | + + + +Hakala, et al. Standards Track [Page 81] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Session-Id | 1 | 1 | + Subscription-Id | 0+ | 0 | + Termination-Cause | 0-1 | 0 | + User-Equipment-Info | 0-1 | 0 | + Used-Service-Unit | 0+ | 0 | + User-Name | 0-1 | 0-1 | + Validity-Time | 0 | 0-1 | + ------------------------------|-----+-----+ + +10.2. Re-Auth-Request/Answer AVP Table + + This section defines AVPs that are specific to the Diameter credit- + control application and that MAY be included in the Diameter Re- + Auth-Request/Answer (RAR/RAA) message [DIAMBASE]. + + Re-Auth-Request/Answer command MAY include the following additional + AVPs: + + +---------------+ + | Command Code | + |-------+-------+ + Attribute Name | RAR | RAA | + ------------------------------+-------+-------+ + CC-Sub-Session-Id | 0-1 | 0-1 | + G-S-U-Pool-Identifier | 0-1 | 0-1 | + Service-Identifier | 0-1 | 0-1 | + Rating-Group | 0-1 | 0-1 | + ------------------------------+-------+-------+ + +11. RADIUS/Diameter Credit-Control Interworking Model + + This section defines the basic principles for the Diameter credit- + control/RADIUS prepaid inter-working model; that is, a message + translation between a RADIUS based prepaid solution and a Diameter + credit-control application. A complete description of the protocol + translations between RADIUS and the Diameter credit-control + application is beyond the scope of this specification and SHOULD be + addressed in another appropriate document, such as the RADIUS prepaid + specification. + + The Diameter credit-control architecture may have a Translation Agent + capable of translation between RADIUS prepaid and Diameter credit- + control protocols. An AAA server (usually the home AAA server) may + act as a Translation Agent and as a Diameter credit-control client + for service elements that use credit-control mechanisms other than + Diameter credit control for instance, RADIUS prepaid. In this case, + the home AAA server contacts the Diameter credit-control server as + part of the authorization process. The interworking architecture is + + + +Hakala, et al. Standards Track [Page 82] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + illustrated in Figure 7, and interworking flow in Figure 8. In a + roaming situation the service element (e.g., the NAS) may be located + in the visited network, and a visited AAA server is usually + contacted. The visited AAA server connects then to the home AAA + server. + + RADIUS Prepaid + +--------+ +---------+ protocol +------------+ +--------+ + | End |<----->| Service |<---------->| Home AAA | |Business| + | User | | Element | | Server | |Support | + +--------+ +-->| | |+----------+|->|System | + | +---------+ ||CC Client || | | + | |+----------+| | | + +--------+ | +------^-----+ +----^---+ + | End |<--+ Credit-Control | | + | User | Protocol | | + +--------+ +-------V--------+ | + |Credit-Control |----+ + | Server | + +----------------+ + + Figure 7: Credit-control architecture with service element + containing translation agent, translating RADIUS + prepaid to Diameter credit-control protocol + + When the AAA server acting as a Translation Agent receives an initial + RADIUS Access-Request message from service element (e.g., NAS + access), it performs regular authentication and authorization. If + the RADIUS Access-Request message indicates that the service element + is capable of credit-control, and if the home AAA server finds that + the subscriber is a prepaid subscriber, then a Diameter credit- + control request SHOULD be sent toward the credit-control server to + perform credit authorization and to establish a credit-control + session. After the Diameter credit-control server checks the end + user's account balance, rates the service, and reserves credit from + the end user's account, the reserved quota is returned to the home + AAA server in the Diameter Credit-Control-Answer. Then the home AAA + server sends the reserved quota to the service element in the RADIUS + Access-Accept. + + At the expiry of the allocated quota, the service element sends a new + RADIUS Access-Request containing the units used this far to the home + AAA server. The home AAA server shall map a RADIUS Access-Request + containing the reported units to the Diameter credit-control server + in a Diameter Credit-Control-Request (UPDATE_REQUEST). The Diameter + credit-control server debits the used units from the end user's + account and allocates a new quota that is returned to the home AAA + server in the Diameter Credit-Control-Answer. The quota is + + + +Hakala, et al. Standards Track [Page 83] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + transferred to the service element in the RADIUS Access-Accept. When + the end user terminates the service, or when the entire quota has + been used, the service element sends a RADIUS Access-Request. To + debit the used units from the end user's account and to stop the + credit-control session, the home AAA server sends a Diameter Credit- + Control-Request (TERMINATION_REQUEST) to the credit-control server. + The Diameter credit-control server acknowledges the session + termination by sending a Diameter Credit-Control-Answer to the home + AAA server. The RADIUS Access-Accept is sent to the NAS. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Hakala, et al. Standards Track [Page 84] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + A following diagram illustrates a RADIUS prepaid - Diameter credit- + control interworking sequence. + + Service Element Translation Agent + (e.g., NAS) (CC Client) CC Server + | Access-Request | | + |----------------------->| | + | | CCR (initial) | + | |----------------------->| + | | CCA (Granted-Units) | + | |<-----------------------| + | Access-Accept | | + | (Granted-Units) | | + |<-----------------------| | + : : : + | Access-Request | | + | (Used-Units) | | + |----------------------->| | + | | CCR (update, | + | | Used-Units) | + | |----------------------->| + | | CCA (Granted-Units) | + | |<-----------------------| + | Access-Accept | | + | (Granted-Units) | | + |<-----------------------| | + : : : + | Access-Request | | + |----------------------->| | + | | CCR (terminate, | + | | Used-Units) | + | |----------------------->| + | | CCA | + | |<-----------------------| + | Access-Accept | | + |<-----------------------| | + | | | + + Figure 8: Message flow example with RADIUS prepaid - + Diameter credit-control interworking + +12. IANA Considerations + + This section contains the namespaces that have either been created in + this specification, or the values assigned to existing namespaces + managed by IANA. + + + + + +Hakala, et al. Standards Track [Page 85] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + In the subsections below, when we speak about review by a Designated + Expert, please note that the designated expert will be assigned by + the IESG. Initially, such Expert discussions take place on the AAA + WG mailing list. + +12.1. Application Identifier + + This specification assigns the value 4, 'Diameter Credit Control', to + the Application Identifier namespace defined in [DIAMBASE]. See + section 1.3 for more information. + +12.2. Command Codes + + This specification uses the value 272 from the Command code namespace + defined in [DIAMBASE] for the Credit-Control-Request (CCR) and + Credit-Control-Answer (CCA) commands. + +12.3. AVP Codes + + This specification assigns the values 411 - 461 from the AVP code + namespace defined in [DIAMBASE]. See section 8 for the assignment of + the namespace in this specification. + +12.4. Result-Code AVP Values + + This specification assigns the values 4010, 4011, 4012, 5030, 5031 + from the Result-Code AVP value namespace defined in [DIAMBASE]. See + section 9 for the assignment of the namespace in this specification. + +12.5. CC-Request-Type AVP + + As defined in section 8.3, the CC-Request-Type AVP includes + Enumerated type values 1 - 4. IANA has created and is maintaining a + namespace for this AVP. All remaining values are available for + assignment by a Designated Expert [IANA]. + +12.6. CC-Session-Failover AVP + + As defined in section 8.4, the CC-Failover-Supported AVP includes + Enumerated type values 0 - 1. IANA has created and is maintaining a + namespace for this AVP. All remaining values are available for + assignment by a Designated Expert [IANA]. + + + + + + + + + +Hakala, et al. Standards Track [Page 86] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +12.7. CC-Unit-Type AVP + + As defined in section 8.32, the CC-Unit-Type AVP includes Enumerated + type values 0 - 5. IANA has created and is maintaining a namespace + for this AVP. All remaining values are available for assignment by a + Designated Expert [IANA]. + +12.8. Check-Balance-Result AVP + + As defined in section 8.6, the Check-Balance-Result AVP includes + Enumerated type values 0 - 1. IANA has created and is maintaining a + namespace for this AVP. All remaining values are available for + assignment by a Designated Expert [IANA]. + +12.9. Credit-Control AVP + + As defined in section 8.13, the Credit-Control AVP includes + Enumerated type values 0 - 1. IANA has created and is maintaining a + namespace for this AVP. All remaining values are available for + assignment by a Designated Expert [IANA]. + +12.10. Credit-Control-Failure-Handling AVP + + As defined in section 8.14, the Credit-Control-Failure-Handling AVP + includes Enumerated type values 0 - 2. IANA has created and is + maintaining a namespace for this AVP. All remaining values are + available for assignment by a Designated Expert [IANA]. + +12.11. Direct-Debiting-Failure-Handling AVP + + As defined in section 8.15, the Direct-Debiting-Failure-Handling AVP + includes Enumerated type values 0 - 1. IANA has created and is + maintaining a namespace for this AVP. All remaining values are + available for assignment by a Designated Expert [IANA]. + +12.12. Final-Unit-Action AVP + + As defined in section 8.35, the Final-Unit-Action AVP includes + Enumerated type values 0 - 2. IANA has created and is maintaining a + namespace for this AVP. All remaining values are available for + assignment by a Designated Expert [IANA]. + +12.13. Multiple-Services-Indicator AVP + + As defined in section 8.40, the Multiple-Services-Indicator AVP + includes Enumerated type values 0 - 1. IANA has created and is + maintaining a namespace for this AVP. All remaining values are + available for assignment by a Designated Expert [IANA]. + + + +Hakala, et al. Standards Track [Page 87] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +12.14. Redirect-Address-Type AVP + + As defined in section 8.38, the Redirect-Address-Type AVP includes + Enumerated type values 0 - 3. IANA has created and is maintaining a + namespace for this AVP. All remaining values are available for + assignment by a Designated Expert [IANA]. + +12.15. Requested-Action AVP + + As defined in section 8.41, the Requested-Action AVP includes + Enumerated type values 0 - 3. IANA has created and is maintaining a + namespace for this AVP. All remaining values are available for + assignment by a Designated Expert [IANA]. + +12.16. Subscription-Id-Type AVP + + As defined in section 8.47, the Subscription-Id-Type AVP includes + Enumerated type values 0 - 4. IANA has created and is maintaining a + namespace for this AVP. All remaining values are available for + assignment by a Designated Expert [IANA]. + +12.17. Tariff-Change-Usage AVP + + As defined in section 8.27, the Tariff-Change-Usage AVP includes + Enumerated type values 0 - 2. IANA has created and is maintaining a + namespace for this AVP. All remaining values are available for + assignment by a Designated Expert [IANA]. + +12.18. User-Equipment-Info-Type AVP + + As defined in section 8.50, the User-Equipment-Info-Type AVP includes + Enumerated type values 0 - 3. IANA has created and is maintaining a + namespace for this AVP. All remaining values are available for + assignment by a Designated Expert [IANA]. + +13. Credit-Control Application Related Parameters + + Tx timer + + When real-time credit-control is required, the credit-control + client contacts the credit-control server before and while the + service is provided to an end user. Due to the real-time nature + of the application, the communication delays SHOULD be minimized; + e.g., to avoid an overly long service setup time experienced by + the end user. The Tx timer is introduced to control the waiting + time in the client in the Pending state. When the Tx timer + elapses, the credit-control client takes an action to the end user + according to the value of the Credit-Control-Failure-Handling AVP + + + +Hakala, et al. Standards Track [Page 88] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + or Direct-Debiting-Failure-Handling AVP. The recommended value is + 10 seconds. + + Tcc timer + + The Tcc timer supervises an ongoing credit-control session in the + credit-control server. It is RECOMMENDED to use the Validity-Time + as input to set the Tcc timer value. In case of transient + failures in the network, the Diameter credit-control server might + change to Idle state. To avoid this, the Tcc timer MAY be set so + that Tcc equals to 2 x Validity-Time. + + Credit-Control-Failure-Handling and Direct-Debiting-Failure-Handling + + Client implementations may offer the possibility of locally + configuring these AVPs. In such a case their value and behavior + is defined in section 5.7 for the Credit-Control-Failure-Handling + and in section 6.5 for the Direct-Debiting-Failure-Handling. + +14. Security Considerations + + The Diameter base protocol [DIAMBASE] requires that each Diameter + implementation use underlying security; i.e., IPsec or TLS. These + mechanisms are believed to provide sufficient protection under the + normal Internet threat model; that is, assuming that the authorized + nodes engaging in the protocol have not been compromised, but that + the attacker has complete control over the communication channels + between them. This includes eavesdropping, message modification, + insertion, and man-in-the-middle and replay attacks. Note also that + this application includes a mechanism for application layer replay + protection by means of the Session-Id from [DIAMBASE] and CC- + Request-Number, which is specified in this document. The Diameter + credit-control application is often used within one domain, and there + may be a single hop between the peers. In these environments, the + use of TLS or IPsec is sufficient. The details of TLS and IPsec + related security considerations are discussed in the [DIAMBASE]. + + Because this application handles monetary transactions (directly or + indirectly), it increases the interest for various security attacks. + Therefore, all parties communicating with each other MUST be + authenticated, including, for instance, TLS client-side + authentication. In addition, authorization of the client SHOULD be + emphasized; i.e., that the client is allowed to perform credit- + control for a certain user. The specific means of authorization are + outside of the scope of this specification but can be, for instance, + manual configuration. + + + + + +Hakala, et al. Standards Track [Page 89] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Another kind of threat is malicious modification, injection, or + deletion of AVPs or complete credit-control messages. The credit- + control messages contain sensitive billing related information (such + as subscription Id, granted units, used units, cost information) + whose malicious modification can have financial consequences. + Sometimes simply delaying the credit-control messages can cause + disturbances in the credit-control client or server. + + Even without any modification to the messages, an adversary can + invite a security threat by eavesdropping, as the transactions + contain private information about the user. Also, by monitoring the + credit-control messages one can collect information about the + credit-control server's billing models and business relationships. + + When third-party relays or proxy are involved, the hop-by-hop + security does not necessarily provide sufficient protection for + Diameter user session. In some cases, it may be inappropriate to + send Diameter messages, such as CCR and CCA, containing sensitive + AVPs via untrusted Diameter proxy agents, as there are no assurances + that third-party proxies will not modify the credit-control commands + or AVP values. + +14.1. Direct Connection with Redirects + + A Diameter credit-control agent cannot always know whether agents + between it and the end user's Diameter credit-control server are + reliable. In this case, the Diameter credit-control agent doesn't + have a routing entry in its Diameter Routing Table (defined in + [DIAMBASE], section 2.7) for the realm of the credit-control server + in the end user's home domain. The Diameter credit-control agent can + have a default route configured to a local Redirect agent, and it + redirects the CCR message to the redirect agent. The local Redirect + agent then returns a redirect notification (Result-code 3006, + DIAMETER_REDIRECT_INDICATION) to the credit-control agent, as well as + Diameter credit-control server(s) information (Redirect-Host AVP) and + information (Redirect-Host-Usage AVP) about how the routing entry + resulting from the Redirect-Host is to be used. The Diameter + credit-control agent then forwards the CCR message directly to one of + the hosts identified by the CCA message from the redirect agent. If + the value of the Redirect-Host-Usage AVP is unequal to zero, all + following messages are sent to the host specified in the Redirect- + Host AVP until the time specified by the Redirect-Max-Cache-Time AVP + is expired. + + There are some authorization issues even with redirects. There may + be attacks toward nodes that have been properly authorized, but that + abuse their authorization or have been compromised. These issues are + discussed more widely in [DIAMEAP], section 8. + + + +Hakala, et al. Standards Track [Page 90] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +15. References + +15.1. Normative References + + [DIAMBASE] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. + Arkko, "Diameter Base Protocol", RFC 3588, September + 2003. + + [3GPPCHARG] 3rd Generation Partnership Project; Technical + Specification Group Services and System Aspects, Service + aspects; Charging and Billing, (release 5), 3GPP TS + 22.115 v. 5.2.1, 2002-03. + + [SIP] 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. + + [NAI] Aboba, B. and M. Beadles, "The Network Access + Identifier", RFC 2486, January 1999. + + [E164] Recommendation E.164/I.331 (05/97): The International + Public Telecommunication Numbering Plan. 1997. + + [CE164] Complement to ITU-T Recommendation E.164 (05/1997):"List + of ITU-T Recommendation E.164 assigned country codes", + June 2000. + + [E212] Recommendation E.212 (11/98): The international + identification plan for mobile terminals and mobile + users. 1998. + + [CE212] Complement to ITU-T Recommendation E.212 (11/1997):" List + of mobile country or geographical area codes", February + 1999. + + [IANA] Narten, T. and H. Alvestrand, "Guidelines for Writing an + IANA Considerations Section in RFCs", BCP 26, RFC 2434, + October 1998. + + [IPv4] Postel, J., "Internet Protocol", STD 5, RFC 791, + September 1981. + + [IPv6Addr] Hinden, R. and S. Deering, "Internet Protocol Version 6 + (IPv6) Addressing Architecture", RFC 3513, April 2003. + + [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate + Requirement Levels", BCP 14, RFC 2119, March 1997. + + + +Hakala, et al. Standards Track [Page 91] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + [ISO4217] Codes for the representation of currencies and funds, + International Standard ISO 4217,2001 + + [NASREQ] Calhoun, P., Zorn, G., Spence, D., and D. Mitton, + "Diameter Network Access Server Application", RFC 4005, + August 2005. + + [AAATRANS] Aboba, B. and J. Wood, "Authentication, Authorization and + Accounting (AAA) Transport Profile", RFC 3539, June 2003. + + [URL] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform + Resource Locators (URL)", RFC 1738, December 1994. + + [RAD802.1X] Congdon, P., Aboba, B., Smith, A., Zorn, G., and J. + Roese, "IEEE 802.1X Remote Authentication Dial In User + Service (RADIUS) Usage Guidelines", RFC 3580, September + 2003. + + [EUI64] IEEE, "Guidelines for 64-bit Global Identifier (EUI-64) + Registration Authority", + http://standards.ieee.org/regauth/oui/tutorials/ + EUI64.html March 1997. + + [3GPPIMEI] 3rd Generation Partnership Project; Technical + Specification Group Core Network, Numbering, addressing + and identification, (release 5), 3GPP TS 23.003 v. 5.8.0, + 2003-12 + +15.2. Informative References + + [RFC2866] Rigney, C., "RADIUS Accounting", RFC 2866, June 2000. + + [DIAMMIP] Calhoun, P., Johansson, T., Perkins, C., Hiller, T., and + P. McCann, "Diameter Mobile IPv4 Application", RFC 4004, + August 2005. + + [DIAMEAP] Eronen, P., Hiller, T., and G. Zorn, "Diameter Extensible + Authentication Protocol (EAP) Application", Work in + Progress. + + [RFC3725] Rosenberg, J., Peterson, J., Schulzrinne, H., and G. + Camarillo, "Best Current Practices for Third Party Call + Control (3pcc) in the Session Initiation Protocol (SIP)", + BCP 85, RFC 3725, April 2004. + + + + + + + +Hakala, et al. Standards Track [Page 92] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +16. Acknowledgements + + The authors would like to thank Bernard Aboba, Jari Arkko, Robert + Ekblad, Pasi Eronen, Benny Gustafsson, Robert Karlsson, Avi Lior, + Paco Marin, Jussi Maki, Jeff Meyer, Anne Narhi, John Prudhoe, + Christopher Richards, Juha Vallinen, and Mark Watson for their + comments and suggestions. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Hakala, et al. Standards Track [Page 93] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +Appendix A. Credit-Control Sequences + +A.1. Flow I + + NAS + End User (CC Client) AAA Server CC Server + |(1)User Logon |(2)AA Request (CC AVPs) | + |------------------>|------------------->| | + | | |(3)CCR(initial, CC AVPs) + | | |------------------->| + | | | (4)CCA(Granted-Units) + | | |<-------------------| + | |(5)AA Answer(Granted-Units) | + |(6)Access granted |<-------------------| | + |<----------------->| | | + | | | | + : : : : + | |(7)CCR(update,Used-Units) | + | |------------------->|(8)CCR | + | | | (update,Used-Units) + | | |------------------->| + | | |(9)CCA(Granted-Units) + | |(10)CCA(Granted-Units)<------------------| + | |<-------------------| | + : : : : + | (Auth. lifetime expires) | | + | |(11) AAR (CC AVP) | | + | |------------------->| | + | | (12) AAA | | + | |<-------------------| | + : : : : + : : : : + |(13) User logoff | | | + |------------------>|(14)CCR(term.,Used-Units) | + | |------------------->|(15)CCR | + | | | (term.,Used-Units) + | | |------------------->| + | | | (16)CCA | + | | (17)CCA |<-------------------| + | |<-------------------| | + | |(18)STR | | + | |------------------->| | + | | (19)STA | | + | |<-------------------| | + + Figure A.1: Flow I + + + + + +Hakala, et al. Standards Track [Page 94] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + A credit-control flow for Network Access Services prepaid is shown in + Figure A.1. The Diameter [NASREQ] is implemented in the Network + Access Server (NAS). The focus of this flow is in the credit + authorization. + + The user logs on to the network (1). The Diameter NAS sends a + Diameter AA-Request (AAR) to the home Diameter AAA server. The + credit-control client populates the AAR with the Credit-Control AVP + set to CREDIT_AUTHORIZATION, and service-specific AVPs are included, + as usual [NASREQ]. The home Diameter AAA server performs service- + specific Authentication and Authorization, as usual. The home + Diameter AAA server determines that the user is a prepaid user and + notices from the Credit-Control AVP that the NAS has credit-control + capabilities. It sends a Diameter Credit-Control-Request with CC- + Request-Type set to INITIAL_REQUEST to the Diameter credit-control + server to perform credit authorization (3) and to establish a + credit-control session. (The home Diameter AAA server may forward + service-specific AVPs received from the NAS as input for the rating + process.) The Diameter credit-control server checks the end user's + account balance, rates the service, and reserves credit from the end + user's account. The reserved quota is returned to the home Diameter + AAA server in the Diameter Credit-Control-Answer (4). The home + Diameter AAA server sends the reserved quota to the NAS in the + Diameter AA-Answer (AAA). Upon successful AAA, the NAS starts the + credit-control session and starts monitoring the granted units (5). + The NAS grants access to the end user (6). At the expiry of the + allocated quota, the NAS sends a Diameter Credit-Control-Request with + CC-Request-Type set to UPDATE_REQUEST to the Home Diameter AAA server + (7). This message contains the units used thus far. The home + Diameter AAA server forwards the CCR to the Diameter credit-control + server (8). The Diameter credit-control server debits the used units + from the end user's account and allocates a new quota that is + returned to the home Diameter AAA server in the Diameter Credit- + Control-Answer (9). The message is forwarded to the NAS (10). + During the ongoing credit-control session, the authorization lifetime + expires, and the authorization/authentication client in the NAS + performs service specific re-authorization to the home Diameter AAA + server, as usual. The credit-control client populates the AAR with + the Credit-Control AVP set to RE_AUTHORIZATION, indicating that the + credit-control server shall not be contacted, as the credit + authorization is controlled by the burning rate of the granted units + (11). The home Diameter AAA server performs service-specific re- + authorization as usual and returns the AA-Answer to the NAS (12). + The end user logs off from the network (13). To debit the used units + from the end user's account and to stop the credit-control session, + the NAS sends a Diameter Credit-Control-Request with CC-Request-Type + set to TERMINATION_REQUEST to the home Diameter AAA server (14). The + home Diameter AAA server forwards the CCR to the credit-control + + + +Hakala, et al. Standards Track [Page 95] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + server (15). The Diameter credit-control server acknowledges the + session termination by sending a Diameter Credit-Control-Answer to + the home Diameter AAA server (16). The home Diameter AAA server + forwards the answer to the NAS (17). STR/STA takes place between the + NAS and home Diameter AAA server, as usual (18-19). + +A.2. Flow II + + SIP Proxy/Registrar AAA + A (CC Client) Server B CC Server + |(i) REGISTER | | | | + |------------->|(ii) | | | + | |------------->| | | + | |authentication & | | + | |authorization | | | + | |<-------------| | | + |(iii)200 OK | | | + |<-------------| | | + : : : : + |(1) INVITE | : + |------------->| + | |(2) CCR (Initial, SIP specific AVP) | + | |------------------------------------------->| + | |(3) CCA (Granted-Units) | + | |<-------------------------------------------| + | |(4) INVITE | | + | |---------------------------->| | + : : : : + | |(5) CCR (update, Used-Units) | + | |------------------------------------------->| + | |(6) CCA (Granted-Units) | + | |<-------------------------------------------| + : : : : + |(7) BYE | | | + |------------->| | | + | |(8) BYE | | + | |---------------------------->| | + | |(9) CCR (termination, Used-Units) | + | |------------------------------------------->| + | |(10) CCA () | + | |<-------------------------------------------| + | | | | + + Figure A.2: Flow II + + + + + + + +Hakala, et al. Standards Track [Page 96] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + This is an example of Diameter credit-control for SIP sessions. + Although the flow focuses on illustrating the usage of credit-control + messages, the SIP signaling is inaccurate, and the diagram is not by + any means an attempt to define a service provider's SIP network. + However, for the sake of this example, some assumptions are made + below. + + Typically, prepaid services based, for example, on time usage for SIP + session require an entity in the service provider network to + intercept all the requests within the SIP dialog in order to detect + events, such as session establishment and session release, that are + essential to perform credit-control operations with the credit- + control server. Therefore, in this example, it is assumed that the + SIP Proxy adds a Record-Route header in the initial SIP INVITE to + make sure that all the future requests in the created dialog traverse + through it (for the definitions of 'Record-Route' and 'dialog' please + refer to [SIP]). Finally, the degree of credit-control measuring of + the media by the proxy depends on the business model design used in + setting up the end system and proxies in the SIP network. + + The end user (SIP User Agent A) sends REGISTER with credentials (i). + The SIP Proxy sends a request to the home AAA server to perform + Multimedia authentication and authorization by using, for instance, + Diameter Multimedia application (ii). The home AAA server checks + that the credentials are correct and checks the user profile. + Eventually, 200 OK response (iii) is sent to the UA. Note that the + Authentication and Authorization is valid for the registration + validity period duration (i.e., until re-registration is performed). + Several SIP sessions may be established without re-authorization. + + UA A sends an INVITE (1). The SIP Proxy sends a Diameter Credit- + Control-Request (INITIAL_REQUEST) to the Diameter credit-control + server (2). The Credit-Control-Request contains information obtained + from the SIP signaling describing the requested service (e.g., + calling party, called party, Session Description Protocol + attributes). The Diameter credit-control server checks the end + user's account balance, rates the service, and reserves credit from + the end user's account. The reserved quota is returned to the SIP + Proxy in the Diameter Credit-Control-Answer (3). The SIP Proxy + forwards the SIP INVITE to UA B (4). B's phone rings, and B answers. + The media flows between them, and the SIP Proxy starts measuring the + quota. At the expiry of the allocated quota, the SIP Proxy sends a + Diameter Credit-Control-Request (UPDATE_REQUEST) to the Diameter + credit-control server (5). This message contains the units used thus + far. The Diameter credit-control server debits the used units from + the end user's account and allocates new credit that is returned to + the SIP Proxy in the Diameter Credit-Control-Answer (6). The end + user terminates the service by sending a BYE (7). The SIP Proxy + + + +Hakala, et al. Standards Track [Page 97] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + forwards the BYE message to UA B (8) and sends a Diameter Credit- + Control-Request (TERMINATION_REQUEST) to the credit-control server + (9). The Diameter credit-control server acknowledges the session + termination by sending a Diameter Credit-Control-Answer to the SIP + Proxy (10). + +A.3. Flow III + + MMS Server + A (CC Client) B CC Server + |(1) Send MMS | | | + |--------------->| | | + | |(2) CCR (event, DIRECT_DEBITING,| + | | MMS specific AVP) | + | |-------------------------------->| + | |(3) CCA (Granted-Units) | + | |<--------------------------------| + |(4) Send MMS Ack| | | + |<---------------| | | + | |(5) Notify MMS | | + | |--------------->| | + : : : : + | |(6) Retrieve MMS| | + | |<---------------| | + | |(7) Retrieve MMS| | + | | Ack | | + | |--------------->| | + | | | | + + Figure A.3: Flow III + + A credit-control flow for Multimedia Messaging Services is shown in + Figure A.3. The sender is charged as soon as the messaging server + successfully stores the message. + + The end user A sends a Multimedia Message (MMS) to the MMS server + (1). The MMS server stores the message and sends a Diameter Credit- + Control-Request (EVENT_REQUEST with Requested-Action DIRECT_DEBITING) + to the Diameter credit-control server (2). The Credit-Control- + Request contains information about the MMS message (e.g., size, + recipient address, image coding type). The Diameter credit-control + server checks the end user's account balance, rates the service, and + debits the service from the end user's account. The granted quota is + returned to the MMS server in the Diameter Credit-Control-Answer (3). + The MMS server acknowledges the successful reception of the MMS + message (4). The MMS Server notifies the recipient about the new MMS + (5), and end user B retrieves the message from the MMS message store + (6),(7). + + + +Hakala, et al. Standards Track [Page 98] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +A.4. Flow IV + + MMS Server + Content Server (CC Client) B CC Server + |(1) Send MMS | | | + |--------------->| | | + | |(2) CCR (event, CHECK_BALANCE, | + | | MMS specific AVP) | + | |-------------------------------->| + | |(3) CCA (ENOUGH_CREDIT) | + | |<--------------------------------| + |(4) Send MMS Ack| | | + |<---------------| | | + | |(5) Notify MMS | | + | |--------------->| | + : : : : + | |(6) Retrieve MMS| | + | |<---------------| | + | |(7) CCR (event, DIRECT_DEBITING,| + | | MMS specific AVP) | + | |-------------------------------->| + | |(8) CCA (Granted-Units) | + | |<--------------------------------| + | |(9) Retrieve MMS| | + | | Ack | | + | |--------------->| | + | | | | + + Figure A.4: Flow IV + + This is an example of Diameter credit-control for direct debiting + using the Multimedia Messaging Service environment. Although the + flow focuses on illustrating the usage of credit-control messages, + the MMS signaling is inaccurate, and the diagram is not by any means + an attempt to define any service provider's MMS configuration or + billing model. + + A credit-control flow for Multimedia Messaging Service is shown in + Figure A.4. The recipient is charged at the message delivery. + + A content server sends a Multimedia Message (MMS) to the MMS server + (1) that stores the message. The message recipient will be charged + for the MMS message in this case. As there can be a substantially + long time between the receipt of the message at the MMS server and + the actual retrieval of the message, the MMS server does not + establish any credit-control session to the Diameter credit-control + server but performs first only a balance check (without any credit + reservation) by sending a Diameter Credit-Control-Request + + + +Hakala, et al. Standards Track [Page 99] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + (EVENT_REQUEST with Requested-Action CHECK_BALANCE) to verify that + end user B can cover the cost for the MMS (2). The Diameter credit- + control server checks the end user's account balance and returns the + answer to the MMS server in the Diameter Credit-Control-Answer (3). + The MMS server acknowledges the successful reception of the MMS + message (4). The MMS server notifies the recipient of the new MMS + (5), and after some time end user B retrieves the message from the + MMS message store (6). The MMS server sends a Diameter Credit- + Control-Request (EVENT_REQUEST with Requested-Action: + DIRECT_DEBITING) to the Diameter credit-control server (7). The + Credit-Control-Request contains information about the MMS message + (e.g., size, recipient address, coding type). The Diameter credit- + control server checks the end user's account balance, rates the + service, and debits the service from the end user's account. The + granted quota is returned to the MMS server in the Diameter Credit- + Control-Request (8). The MMS is transferred to end user B (9). + + Note that the transfer of the MMS message can take an extended time + and can fail, in which case a recovery action is needed. The MMS + server should return the already debited units to the user's account + by using the REFUND action described in section 6.4. + +A.5. Flow V + + SIP Controller + A (CC Client) B CC Server + |(1)INVITE B(SDP)| | | + |--------------->| | | + | |(2) CCR (event, PRICE_ENQUIRY, | + | | SIP specific AVPs) | + | |-------------------------------->| + | |(3) CCA (Cost-Information) | + | |<--------------------------------| + | (4)MESSAGE(URL)| | | + |<---------------| | | + |(5)HTTP GET | | | + |--------------->| | | + |(6)HTTP POST | | | + |--------------->|(7)INVITE(SDP) | | + | |--------------->| | + | | (8)200 OK | | + | (9)200 OK |<---------------| | + |<---------------| | | + + Figure A.5: Flow V + + + + + + +Hakala, et al. Standards Track [Page 100] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + This is an example of Diameter credit-control for SIP sessions. + Although the flow focuses on illustrating the usage of credit-control + messages, the SIP signaling is inaccurate, and the diagram is not by + any means an attempt to define a service provider's SIP network. + + Figure A.5 is an example of Advice of Charge (AoC) service for SIP + call. User A can be either a postpaid or prepaid subscriber using + the AoC service. It is assumed that the SIP controller also has HTTP + capabilities and delivers an interactive AoC web page with, for + instance, the cost information, the details of the call derived from + the SDP, and a button to accept/not accept the charges. (There may + be many other ways to deliver AoC information; however, this flow + focuses on the use of the credit-control messages.) The user has + been authenticated and authorized prior to initiating the call and + subscribed to AoC service. + + UA A sends an INVITE with SDP to B (1). The SIP controller + determines that the user is subscribed to AoC service and sends a + Diameter Credit-Control-Request (EVENT_REQUEST with Requested-Action: + PRICE_ENQUIRY) to the Diameter credit-control server (2). The + Credit-Control-Request contains SIP specific AVPs derived from the + SIP signaling, describing the requested service (e.g., calling party, + called party, Session Description Protocol attributes). The Diameter + credit-control server determines the cost of the service and returns + the Credit-Control-Answer including the Cost-Information AVP (3). + The SIP controller manufactures the AoC web page with information + received in SIP signaling and with the cost information received from + the credit-control server. Then it sends a SIP MESSAGE that contains + a URL pointing to the AoC information web page (4). At the receipt + of the SIP MESSAGE, A's UA automatically invokes the web browser that + retrieves the AoC information (5). The user clicks on a proper + button and accepts the charges (6). The SIP controller continues the + session and sends the INVITE to the B party, which accepts the call + (7,8,9). + + + + + + + + + + + + + + + + + +Hakala, et al. Standards Track [Page 101] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +A.6. Flow VI + + Gaming Server + End User (CC Client) CC Server + | (1)Service Delivery | | + |<---------------------->| | + : : : + : : : + | |(2)CCR(event,REFUND,Requested- + | |Service-Unit,Service-Parameter-Info) + | |----------------------->| + | | (3)CCA(Cost-Information) + | |<-----------------------| + | (4)Notification | | + |<-----------------------| | + + Figure A.6: Flow VI + + Figure A.6 illustrates a credit-control flow for the REFUND case. It + is assumed that there is a trusted relationship and secure connection + between the Gaming server and the Diameter credit-control server. + The end user may be a prepaid subscriber or a postpaid subscriber. + + While the end user is playing the game (1), she enters a new level + that entitles her to a bonus. The Gaming server sends a Diameter + Credit-Control-Request (EVENT_REQUEST with Requested-Action: + REFUND_ACCOUNT) to the Diameter credit-control server (2). The + Credit-Control-Request Request contains the Requested-Service-Unit + AVP with the CC-Service-Specific-Units containing the number of + points the user just won. The Service-Parameter-Info AVP is also + included in the request and specifies the service event to be rated + (e.g., Tetris Bonus). From information received, the Diameter + credit-control server determines the amount to be credited, refunds + the user's account, and returns the Credit-Control-Answer, including + the Cost-Information AVP (3). The Cost-Information indicates the + credited amount. At the first opportunity, the Gaming server + notifies the end user of the credited amount (4). + + + + + + + + + + + + + + +Hakala, et al. Standards Track [Page 102] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +A.7. Flow VII + + SIP Controller Top-Up + A (CC Client) Server B CC Server + | | | | | + | | (1) CCR(Update,Used-Unit) | | + | |------------------------------------------>| + | | (2) CCA(Final-Unit, Redirect)| + | |<------------------------------------------| + : : : : : + : : : : : + | | (3) CCR(Update, Used-Units)| | + | |------------------------------------------>| + | | (3a)INVITE("hold") | | + | |--------------------------->| | + | | | (4) CCA(Validity-Time)| + | |<------------------------------------------| + | (5)INVITE | (6)INVITE | | | + |<--------------|------------->| | | + | (7)RTP | | | + |..............................| | | + | | (8)BYE | | | + | |<-------------| | | + | | (9)CCR(Update) | | + | |------------------------------------------>| + | | (10)CCA(Granted-Unit) | + | |<------------------------------------------| + | (12)INVITE | (11)INVITE | | + |<--------------|--------------------------->| | + + Figure A.7: Flow VII + + Figure A.7 is an example of the graceful service termination for a + SIP call. It is assumed that the call is set up so that the + controller is in the call as a B2BUA (Back to Back User Agent) + performing third-party call control (3PCC). Note that the SIP + signaling is inaccurate, as the focus of this flow is in the graceful + service termination and credit-control authorization. The best + practice for 3PCC is defined in [RFC3725]. + + The call is ongoing between users A and B; user A has a prepaid + subscription. At the expiry of the allocated quota, the SIP + controller sends a Diameter Credit-Control-Request (UPDATE_REQUEST) + to the Diameter credit-control server (1). This message contains the + units used thus far. The Diameter credit-control server debits the + used units from the end user's account and allocates the final quota + returned to the SIP controller in the Diameter Credit-Control-Answer + (2). This message contains the Final-Unit-Indication AVP with the + + + +Hakala, et al. Standards Track [Page 103] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Final-Unit-Action set to REDIRECT, the Redirect-Address-Type set to + SIP URI, and the Redirect-Server-Address set to the Top-up server + name (e.g., sip:[email protected]). At the expiry of the + final allocated quota, the SIP controller sends a Diameter Credit- + Control-Request (UPDATE_REQUEST) to the Diameter credit-control + server (3) and places the called party on "hold" by sending an INVITE + with the appropriate connection address in the SDP (3a). The + Credit-Control-Request message contains the units used thus far. The + Diameter credit-control server debits the used units from the end + user's account but does not make any credit reservation. The + Credit-Control-Answer message, which contains the Validity-Time to + supervise the graceful service termination, is returned to the SIP + controller (4). The SIP controller establishes a SIP session between + the prepaid user and the Top-up server (5, 6). The Top-up server + plays an announcement and prompts the user to enter a credit card + number and the amount of money to be used to replenish the account + (7). The Top-up server validates the credit card number and + replenishes the user's account (using some means outside the scope of + this specification) and releases the SIP session (8). The SIP + controller can now assume that communication between the prepaid user + and the Top-up server took place. It sends a spontaneous Credit- + Control-Request (UPDATE_REQUEST) to the Diameter credit-control + server to check whether the account has been replenished (9). The + Diameter credit-control server reserves credit from the end user's + account and returns the reserved quota to the SIP controller in the + Credit-Control-Answer (10). At this point, the SIP controller re- + connects the caller and the called party (11,12). + + + + + + + + + + + + + + + + + + + + + + + + +Hakala, et al. Standards Track [Page 104] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +A.8. Flow VIII + + NAS Top-up CC + End-User (CC Client) AAA Server Server Server + |(1)User Logon |(2)AA Request (CC AVPs) | | + |------------------>|------------------->| | | + | | |(3)CCR(initial, CC AVPs) + | | |------------------->| + | | |(4)CCA(Final-Unit, | + | | | Validity-Time)| + | | |<-------------------| + | |(5)AA Answer(Final-Unit,Validity-Time) | + |(6)Limited Access |<-------------------| | | + | granted | | | | + |<----------------->| | | | + | | | | | + | (7)TCP/HTTP | (8)TCP/HTTP | | + |<----------------->|<----------------------------->| | + | (9) Replenish account | | + |<------------------------------------------------->| | + | | | (10)RAR | + | |<-------------------|<-------------------| + | | (11) RAA | | + | |------------------->|------------------->| + | |(12)CCR(update) | | + | |------------------->|(13)CCR(Update) | + | | |------------------->| + | | |(14)CCA(Granted-Units) + | |(15)CCA(Granted-Units)<------------------| + | |<-------------------| | + + Figure A.8: Flow VIII + + Figure A.8 is an example of the graceful service termination + initiated when the first interrogation takes place because the user's + account is empty. In this example, the credit-control server + supports the server-initiated credit re-authorization. The Diameter + [NASREQ] is implemented in the Network Access Server (NAS). + + The user logs on to the network (1). The Diameter NAS sends a + Diameter AA-Request to the home Diameter AAA server. The credit- + control client populates the AAR with the Credit-Control AVP set to + CREDIT_AUTHORIZATION, and service specific AVPs are included, as + usual [NASREQ]. The home Diameter AAA server performs service + specific Authentication and Authorization, as usual. The home + Diameter AAA server determines that the user has a prepaid + subscription and notices from the Credit-Control AVP that the NAS has + credit-control capabilities. It sends a Diameter Credit-Control- + + + +Hakala, et al. Standards Track [Page 105] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Request with CC-Request-Type set to INITIAL_REQUEST to the Diameter + credit-control server to perform credit authorization (3) and to + establish a credit-control session. (The home Diameter AAA server + may forward service specific AVPs received from the NAS as input for + the rating process.) The Diameter credit-control server checks the + end user's account balance, determines that the account cannot cover + the cost of the service, and initiates the graceful service + termination. The Credit-Control-Answer is returned to the home + Diameter AAA server (4). This message contains the Final-Unit- + Indication AVP and the Validity-Time AVP set to a reasonable amount + of time to give the user a chance to replenish his/her account (e.g., + 10 minutes). The Final-Unit-Indication AVP includes the Final-Unit- + Action set to REDIRECT, the Redirect-Address-Type set to URL, and the + Redirect-Server-Address set to the HTTP Top-up server name. The home + Diameter AAA server sends the received credit-control AVPs to the NAS + in the Diameter AA-Answer (5). Upon successful AAA, the NAS starts + the credit-control session and immediately starts the graceful + service termination, as instructed by the server. The NAS grants + limited access to the user (6). The HTTP client software running in + the user's device opens the transport connection redirected by the + NAS to the Top-up server (7,8). The user is displayed an appropriate + web page on which to enter the credit card number, and the amount of + money to be used to replenish the account, and with a notification + message that she is granted unlimited access if the replenishment + operation will be successfully executed within the next, for example, + 10 minutes. The Top-up server validates the credit card number and + replenishes the user's account (using some means outside the scope of + this specification)(9). After successful account top-up, the + credit-control server sends a Re-Auth-Request message to the NAS + (10). The NAS acknowledges the request by returning the Re-Auth- + Answer message (11) and initiates the credit re-authorization by + sending a Credit-Control-request (UPDATE_REQUEST) to the Diameter + credit-control server (12,13). + + The Diameter credit-control server reserves credit from the end + user's account and returns the reserved quota to the NAS via the home + Diameter AAA server in the Credit-Control-Answer (14,15). The NAS + removes the restriction placed by the graceful service termination + and starts monitoring the granted units. + + + + + + + + + + + + +Hakala, et al. Standards Track [Page 106] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +A.9. Flow IX + + The Diameter credit-control application defines the Multiple- + Services-Credit-Control AVP that can be used to support independent + credit-control of multiple services in a single credit-control (sub-) + session for service elements that have such capabilities. It is + possible to request and allocate resources as a credit pool that is + shared between services or rating groups. + + The flow example hereafter illustrates a usage scenario where the + credit-control client and server support independent credit-control + of multiple services, as defined in section 5.1.2. It is assumed + that Service-Identifiers, Rating-Groups, and their associated + parameters (e.g., IP 5-tuple) are locally configured in the service + element or provisioned by an entity other than the credit-control + server. + + End User Service Element CC Server + (CC client) + |(1)User logon | | + |------------------>|(2)CCR(initial, Service-Id access, | + | | Access specific AVPs, | + | | Multiple-Service-Indicator) | + | |---------------------------------------->| + | |(3)CCA(Multiple-Services-CC ( | + | | Granted-Units(Total-Octets), | + | | Service-Id access, | + | | Validity-time, | + | | G-S-U-Pool-Reference(Pool-Id 1, | + | | Multiplier 10))) | + | |<----------------------------------------| + : : : + |(4)Service-Request (Service 1) | + |------------------>|(5)CCR(update, Multiple-Services-CC( | + | | Requested-Units(), Service-Id 1, | + | | Rating-Group 1)) | + | |---------------------------------------->| + | |(6)CCA(Multiple-Services-CC ( | + | | Granted-Units(Time), | + | | Rating-Group 1, | + | | G-S-U-Pool-Reference(Pool-Id 1, | + | | Multiplier 1))) | + | |<----------------------------------------| + : : : + |(7)Service-Request (Service 2) | + |------------------>| | + + + + + +Hakala, et al. Standards Track [Page 107] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + : : : + : : : + |(8)Service-Request (Service 3&4) | + |------------------>|(9)CCR(update, Multiple-Services-CC ( | + | | Requested-Units(), Service-Id 3, | + | | Rating-Group 2), | + | | Multiple-Services-CC ( | + | | Requested-Units(), Service-Id 4, | + | | Rating-Group 3)) | + | |---------------------------------------->| + | |(10)CCA(Multiple-Services-CC ( | + | | Granted-Units(Total-Octets), | + | | Service-Id 3, Rating-Group 2, | + | | Validity-time, | + | | G-S-U-Pool-Reference(Pool-Id 2, | + | | Multiplier 2)), | + | | Multiple-Services-CC ( | + | | Granted-Units(Total-Octets), | + | | Service-Id 4, Rating-Group 3 | + | | Validity-Time, | + | | Final-Unit-Ind.(Terminate), | + | | G-S-U-Pool-Reference(Pool-Id 2, | + | | Multiplier 5))) | + | |<----------------------------------------| + : : : + : : : + | +--------------+ | | + | |Validity time | |(11)CCR(update, | + | |expires for | | Multiple-Services-CC ( | + | |Service-Id | | Requested-Unit(), | + | | access | | Used-Units(In-Octets,Out-Octets),| + | +--------------+ | Service-Id access)) | + | |---------------------------------------->| + | |(12)CCA(Multiple-Services-CC ( | + | | Granted-Units(Total-Octets), | + | | Service-Id access, | + | | Validity-Time, | + | | G-S-U-Pool-Reference(Pool-Id 1, | + | | Multiplier 10))) | + | |<----------------------------------------| + : : : + : : : + + + + + + + + + +Hakala, et al. Standards Track [Page 108] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + | +--------------+ | | + | |Total Quota | |(13)CCR(update, | + | |elapses for | | Multiple-Services-CC ( | + | |pool 2: | | Requested-Unit(), | + | |service 4 not | | Used-Units(In-Octets,Out-Octets),| + | |allowed, | | Service-Id 3, Rating-group 2), | + | |service 3 cont| | Multiple-Services-CC ( | + | +--------------+ | Used-Units(In-Octets,Out-Octets),| + | | Service-Id 4, Rating-Group 3)) | + | |---------------------------------------->| + | |(14)CCA(Multiple-Services-CC ( | + | | Result-Code 4011, | + | | Service-Id 3)) | + | |<----------------------------------------| + : : : + : : : + |(15) User logoff | | + |------------------>|(16)CCR(term, | + | | Multiple-Services-CC ( | + | | Used-Units(In-Octets,Out-Octets),| + | | Service-Id access), | + | | Multiple-Services-CC ( | + | | Used-Units(Time), | + | | Service-Id 1, Rating-Group 1), | + | | Multiple-Services-CC ( | + | | Used-Units(Time), | + | | Service-Id 2, Rating-Group 1)) | + | |---------------------------------------->| + | |(17)CCA(term) | + | |<----------------------------------------| + + Figure A.9: Flow example independent credit-control of multiple + services in a credit-control (sub-)Session + + The user logs on to the network (1). The service element sends a + Diameter Credit-Control-Request with CC-Request-Type set to + INITIAL_REQUEST to the Diameter credit-control server to perform + credit authorization for the bearer service (e.g., Internet access + service) and to establish a credit-control session (2). In this + message, the credit-control client indicates support for independent + credit-control of multiple services within the session by including + the Multiple-Service-Indicator AVP. The Diameter credit-control + server checks the end user's account balance, with rating information + received from the client (i.e., Service-Id and access specific AVPs), + rates the request, and reserves credit from the end user's account. + Suppose that the server reserves $5 and determines that the cost is + $1/MB. It then returns to the service element a Credit-Control- + Answer message that includes the Multiple-Services-Credit-Control AVP + + + +Hakala, et al. Standards Track [Page 109] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + with a quota of 5MB associated to the Service-Id (access), to a + multiplier value of 10, and to the Pool-Id 1 (3). + + The user uses Service 1 (4). The service element sends a Diameter + Credit-Control-Request with CC-Request-Type set to UPDATE_REQUEST to + the credit-control server to perform credit authorization for service + 1 (5). This message includes the Multiple-Services-Credit-Control + AVP to request service units for Service 1 that belong to Rating- + Group 1. The Diameter credit-control server determines that Service + 1 draws credit resources from the same account as the access service + (i.e., pool 1). It rates the request according to Service- + Id/Rating-Group and updates the existing reservation by requesting + more credit. Suppose that the server reserves $5 more (now the + reservation is $10) and determines that the cost is $0.1/minute. The + server authorizes the whole Rating-Group. It then returns to the + service element a Credit-Control-Answer message that includes the + Multiple-Services-Credit-Control AVP with a quota of 50min. + associated to the Rating-Group 1, to a multiplier value of 1, and to + the Pool-Id 1 (6). The client adjusts the total amount of resources + for pool 1 according the received quota, which gives S for Pool 1 = + 100. + + The user uses Service 2, which belongs to the authorized Rating- + Group, 1 (7). Resources are then consumed from the pool 1. + + The user now requests Services 3 and 4 as well, which are not + authorized (8). The service element sends a Diameter Credit- + Control-Request with CC-Request-Type set to UPDATE_REQUEST to the + credit-control server in order to perform credit authorization for + Services 3 and 4 (9). This message includes two instances of the + Multiple-Services-Credit-Control AVP to request service units for + Service 3 that belong to Rating-Group 2 and for Service 4 that belong + to Rating-Group 3. The Diameter credit-control server determines + that Services 3 and 4 draw credit resources from another account + (i.e., pool 2). It checks the end user's account balance and, + according to Service-Ids/Rating-Groups information, rates the + request. Then it reserves credit from pool 2. + + For example, the server reserves $5 and determines that Service 3 + costs $0.2/MB and Service 4 costs $0.5/MB. The server authorizes + only Services 3 and 4. It returns to the service element a Credit- + Control-Answer message that includes two instances of the Multiple- + Services-Credit-Control AVP (10). One instance grants a quota of + 12.5MB associated to the Service-Id 3 to a multiplier value of 2 and + to the Pool-Id 2. The other instance grants a quota of 5 MB + associated to the Service-Id 4 to a multiplier value of 5 and to the + Pool-Id 2. + + + + +Hakala, et al. Standards Track [Page 110] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + The server also determines that pool 2 is exhausted and Service 4 is + not allowed to continue after these units will be consumed. + Therefore the Final-Unit-Indication AVP with action TERMINATE is + associated to the Service-Id 4. The client calculates the total + amount of resources that can be used for pool 2 according the + received quotas and multipliers, which gives S for Pool 2 = 50. + + The Validity-Time for the access service expires. The service + element sends a Credit-Control-Request message to the server in order + to perform credit re-authorization for Service-Id (access) (11). + This message carries one instance of the Multiple-Services-Credit- + Control AVP that includes the units used by this service. Suppose + that the total amount of used units is 4MB. The client adjusts the + total amount of resources for pool 1 accordingly, which gives S for + Pool 1 = 60. + + The server deducts $4 from the user's account and updates the + reservation by requesting more credit. Suppose that the server + reserves $5 more (now the reservation is $11) and already knows the + cost of the Service-Id (access), which is $1/MB. It then returns to + the service element a Credit-Control-Answer message that includes the + Multiple-Services-Credit-Control AVP with a quota of 5 MB associated + to the Service-Id (access), to a multiplier value of 10, and to the + Pool-Id 1 (12). The client adjusts the total amount of resources for + pool 1 according the received quota, which gives S for Pool 1 = 110. + + Services 3 and 4 consume the total amount of pool 2 credit resources + (i.e., C1*2 + C2*5 >= S). The service element immediately starts the + TERMINATE action concerning Service 4 and sends a Credit-Control- + Request message with CC-Request-Type set to UPDATE_REQUEST to the + credit-control server in order to perform credit re-authorization for + Service 3 (13). This message contains two instances of the + Multiple-Services-Credit-Control AVP to report the units used by + Services 3 and 4. The server deducts the last $5 from the user's + account (pool 2) and returns the answer with Result-Code 4011 in the + Multiple-Services-Credit-Control AVP to indicate that Service 3 can + continue without credit-control (14). + + The end user logs off from the network (15). To debit the used units + from the end user's account and to stop the credit-control session, + the service element sends a Diameter Credit-Control-Request with CC- + Request-Type set to TERMINATION_REQUEST to the credit-control server + (16). This message contains the units consumed by each of the used + services in multiple instances of the Multiple-Services-Credit- + Control AVP. The used units are associated with the relevant + Service-Identifier and Rating-Group. The Diameter credit-control + + + + + +Hakala, et al. Standards Track [Page 111] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + server debits the used units to the user's account (Pool 1) and + acknowledges the session termination by sending a Diameter Credit- + Control-Answer to the service element (17). + +Authors' Addresses + + Harri Hakala + Oy L M Ericsson Ab + Joukahaisenkatu 1 + 20520 Turku + Finland + + Phone: +358 2 265 3722 + EMail: [email protected] + + + Leena Mattila + Oy L M Ericsson Ab + Joukahaisenkatu 1 + 20520 Turku + Finland + + Phone: +358 2 265 3731 + EMail: [email protected] + + + Juha-Pekka Koskinen + Nokia Networks + Hatanpaanvaltatie 30 + 33100 Tampere + Finland + + Phone: +358 7180 74027 + EMail: [email protected] + + + + + + + + + + + + + + + + + +Hakala, et al. Standards Track [Page 112] + +RFC 4006 Diameter Credit-Control Application August 2005 + + + Marco Stura + Nokia Networks + Hiomotie 32 + 00380 Helsinki + Finland + + Phone: +358 7180 64308 + EMail: [email protected] + + + John Loughney + Nokia Research Center + Itamerenkatu 11-13 + 00180 Helsinki + Finland + + Phone: +358 50 483 642 + EMail: [email protected] + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Hakala, et al. Standards Track [Page 113] + +RFC 4006 Diameter Credit-Control Application August 2005 + + +Full Copyright Statement + + Copyright (C) The Internet Society (2005). + + This document is subject to the rights, licenses and restrictions + contained in BCP 78, and except as set forth therein, the authors + retain all their rights. + + This document and the information contained herein are provided on an + "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS + OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET + ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, + INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE + INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED + WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. + +Intellectual Property + + The IETF takes no position regarding the validity or scope of any + Intellectual Property Rights or other rights that might be claimed to + pertain to the implementation or use of the technology described in + this document or the extent to which any license under such rights + might or might not be available; nor does it represent that it has + made any independent effort to identify any such rights. Information + on the 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. + + The IETF invites any interested party to bring to its attention any + copyrights, patents or patent applications, or other proprietary + rights that may cover technology that may be required to implement + this standard. Please address the information to the IETF at ietf- + +Acknowledgement + + Funding for the RFC Editor function is currently provided by the + Internet Society. + + + + + + + +Hakala, et al. Standards Track [Page 114] + |