Harri Hakala, Leena Mattila INTERNET-DRAFT Ericsson, Draft: Juha-Pekka Expires: May 2003 Koskinen, Marco Stura Nokia November 2002 Diameter Credit Control Application Status of this memo This document is an Internet-Draft and is subject to all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or cite them other than as "work in progress". The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/lid-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This document is an individual submission to the IETF. Comments should be directed to the authors. Abstract This document specifies a Diameter application that is used for real- time cost and credit control between a service element and a credit control server in service environment. Diameter accounting messages with additional AVPs are used to transfer service and credit control information between the service element and the credit control server. Hakala et al. expires May 2003 [Page 1] INTERNET-DRAFT Diameter Credit Control Application November, 2002 TABLE OF CONTENTS 1 Introduction 1.1 Requirements language 1.2 Terminology 1.3 Advertising application support 2 Architecture Model 3 Service Credit Control 3.1 Session Based Credit Control 3.1.1 First Interrogation 3.1.2 Interim Interrogation 3.1.3 Final Interrogation 3.1.4 Failure Procedures 3.2 One Time Event 3.2.1 Service Price Enquiry 3.2.2 Balance Check 3.2.3 Direct Debiting 3.2.4 Refund 3.2.5 Failure Procedures 3.3 Credit Control Session State Machine 4 Accounting AVPs 4.1 Abnormal-Termination-Reason AVP 4.2 Accounting-Correlation-Id AVP 4.3 Check-Balance-Result AVP 4.4 Cost-Information AVP 4.5 Credit-Control-Failure-Handling AVP 4.6 Currency-Code AVP 4.7 Direct-Debiting-Failure-Handling AVP 4.8 Exponent AVP 4.9 Final-Unit-Indication AVP 4.10 Granted-Service-Unit AVP 4.11 Requested-Action AVP 4.12 Requested-Service-Unit AVP 4.13 Service-Parameter-Info AVP 4.14 Service-Parameter-type AVP 4.15 Service-Parameter-Value AVP 4.16 Subscription-Id AVP 4.17 Subscription-Id-Data AVP 4.18 Subscription-Id-Type AVP 4.19 Unit-Type AVP 4.20 Unit-Value AVP 4.21 Used-Service-Unit AVP 4.22 Value-Digits AVP 5 Result-Code AVP Values 5.1 Transient Failures 5.2 Permanent Failures 6 AVP Occurrence Table 6.1 Accounting AVP Table Hakala et al. expires March 2003 [Page 2] INTERNET-DRAFT Diameter Credit Control Application November, 2002 7 IANA Considerations 7.1 Application Identifier 7.2 Command Codes 7.3 AVP Codes 7.4 Result-Code AVP Values 7.5 Abnormal-Termination-Reason AVP 7.6 Check-Balance-Result AVP 7.7 Credit-Control-Failure-Handling AVP 7.8 Direct-Debiting-Failure-Handling AVP 7.9 Requested-Service-Unit AVP 7.10 Subscription-Id-Type AVP 7.11 Unit-Type AVP 8 Credit Control Application related configurable parameter 9 Security Considerations 10 References 10.1 Normative 10.2 Non-Normative 11 Acknowledgements 12 Authors addresses 13 Full Copyright Statement 14 Expiration Date 1 Introduction This Diameter application, combined with the Diameter base protocol [DIAMBASE], describes the accounting protocol that can be used for real time cost and credit control in the service environment. The next generation wireless networks specify (e.g. 3G Charging and Billing requirements [3GPPCHARG]) more critical requirements for the accounting applications. The accounting application must be able to rate accounting information in real-time. For example, for the service environment it is vital to be able to rate service event information instantly. There also exists a demand for the end user credit control. The accounting application must be able to check the end user's account for coverage for the requested service event charge prior to execution of that service event. All the chargeable events related to a specific account must be prevented from the end user when the credit of that account is exhausted or expired. Also a mechanism should be provided to indicate to the end user of the charges to be levied for a chargeable event. Hakala et al. expires March 2003 [Page 3] INTERNET-DRAFT Diameter Credit Control Application November, 2002 There are as well services such as gaming or advertising that in some situations rather refund than deduct the end user's account. To fulfill all these needs a new type of accounting application is needed, the credit control application. This application is used for real-time delivery of service event information in the service environment from the service element to the credit control server to minimize the financial risk. 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 Accounting The act of collection of information on resource usage for the purposes of trend analysis, auditing, billing or cost allocation. Accounting Server The accounting server receives accounting data from the service elements and other devices and translates it into session records. It acts as an interface to back-end rating, billing, and operations support systems. Charging In the telecom world charging is synonym to accounting. A function whereby information related to a chargeable event is transferred in order to make it possible to determine usage for which the charged party may be billed. Credit Control Credit control is a mechanism, which 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 if credit is available, credit-reservation, reduction of credit from the end user account when service is completed and refunding of reserved credit not used. Credit Control Server It is located in the home environment and is accessed by service elements in 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. Hakala et al. expires March 2003 [Page 4] INTERNET-DRAFT Diameter Credit Control Application November, 2002 Diameter Credit Control Server A Diameter credit control server is an entity that handles credit control request. Rating The act of determining the cost of the service event. Service A type of task that is performed by a service element for an end user. Service Element A network element that provides a service to end user. A service element itself can include the application service providers or application service providers can be located in an other domain. Service Event Any event which creates value for the end-user. 1.3 Advertising application support Diameter nodes conforming to this specification MAY advertise support by including the value of TBD (X) in the Acct-Application-Id AVP of the Capabilities-Exchange-Request and Capabilities-Exchange-Answer command [DIAMBASE]. 2 Architecture Model A service element provides services to end-users. When accounting is used a service element collects service event information and reports it while and/or after services are provided to an accounting server by using an accounting protocol. Alternatively the accounting server may query the service element for service event information. The accounting protocol can for example be RADIUS accounting protocol or the Diameter base protocol with a Diameter application. If real-time credit control is required, the service element (credit control client) contacts the credit control server with service event information included before the service is provided. The credit control server, depending on the service event information, MAY perform the rating of the service event, pricing of the service event, credit check and credit-reservation from the account. The service element monitors the service execution according to the instructions returned by the credit control server. After the service completion the credit control server deducts the money from the account. If direct debiting/refunding is requested, the credit control server deducts/increases the end user's account, respectively. The service element can also enquire the price of the service or the account balance status from the credit control server. Hakala et al. expires March 2003 [Page 5] INTERNET-DRAFT Diameter Credit Control Application November, 2002 In a multi-service environment it might happen that an end user with already ongoing service (e.g. voice call) issues a new service request (e.g. data service) towards same account or during an active multimedia session an additional media type is added to the session causing a new simultaneous request towards same account. Consequently this SHOULD be considered when units are granted to the services. There MAY be multiple credit control servers in the system for reasons of redundancy and load balancing. The system MAY also contain separate rating server(s) and accounts MAY locate in a centralized database. System internal interfaces can exist to relay messages between servers and an account manager. However the detailed architecture of credit control system and its interfaces are implementation specific and are out of scope of this specification. The credit control protocol is the Diameter base protocol with the Diameter credit control application. accounting +------------+ +-----------+ protocol +--------------+ | End |<----->| Service |<------------>| Accounting | | User | +-->| Element |<-----+ | Server | +------------+ | +-----------+ | +--------------+ | | +------------+ | | | End |<--+ | +--------------+ | User | +------>|Credit Control| +------------+ credit control | Server | protocol +--------------+ The credit control server and accounting server in this architecture model are logical entities. The real configuration MAY combine them into a single host. There MAY exist protocol transparent Diameter relays and redirect agents between credit control client and credit control server. These agents transparently support the Diameter credit control application. 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 Service Control When an end user requests a service the request is forwarded to a service element in the home domain, that is the same administrative domain, in which the end user's credit control server is located. In some cases it might be possible that the service element in the visited domain can offer service event to the end user, but in that Hakala et al. expires March 2003 [Page 6] INTERNET-DRAFT Diameter Credit Control Application November, 2002 case a commercial agreement must exist between the service element in the visited domain and in the home domain. The service element SHOULD authenticate and authorize the end user before any request is sent to the credit control server. The way how the authentication and/or authorization are performed in the service element and the authentication and/or authorization messages that are used are not defined in this application. The methods defined in other Diameter applications or other legacy authentication and authorization methods can be used. Each credit control session MUST have globally unique Session-Id as defined in [DIAMBASE] and it MUST NOT be changed during the life time of a credit control session. The Diameter credit control client in the service element MAY get information from the authorization server regarding the way accounting data shall be forwarded (accounting protocol, credit control protocol or both) based on its knowledge of the end user. This means that the accounting information is forwarded to the accounting server as defined in [DIAMBASE], the credit control server SHOULD be contacted before the service event is offered to the end user or both the accounting protocol and the credit control protocol MAY be used in parallel. 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]. The Accounting-Realtime-Required AVP is not used by this application. Instead of or in addition to the Accounting-Realtime- Required AVP the authorization server MAY include the Credit-Control- Failure-Handling AVP and 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. The usage of Credit-Control-Failure-Handling AVP and the Direct-Debiting-Failure- Handling AVP gives flexibility to have different failure handling for credit control session and one time event direct debiting. The credit control server MAY override the failure handling for credit control session by including the Credit-Control-Failure-Handling AVP in the Accounting-Answer. The usage of separate AVPs makes it possible to have different failure handling towards accounting servers and credit control servers, in case both should be used parallel. It is recommended that the client complements the credit control failure procedures with backup accounting flow towards an accounting server. With different combinations of above AVPs different safety levels can be built. For example by choosing the Credit-Control-Failure-Handling AVP equal to CONTINUE and Accounting-Realtime-Required AVP equal to DELIVER_AND_GRANT the service can be granted to the end user even if the connection to the credit control server is down but the accounting server is able to collect the accounting information, Hakala et al. expires March 2003 [Page 7] INTERNET-DRAFT Diameter Credit Control Application November, 2002 provided that there is information exchange taking place between the accounting server and credit control server. If authentication and authorization is done based on Diameter application the authorization server MAY include the Acct-Interim- Interval AVP to control the operation of the device in the service element operating as a client as defined in [DIAMBASE]. If the Acct- Interim-Interval AVP is included then the interim interval MAY be present in the request message sent to the credit control server. The Diameter credit control server MAY override the interim interval. It is up to the credit control server to determine, even independently from the requested value, the allowed interim interval to be used for consumption of the granted service units. The credit control server MAY return the interim interval in the Answer message to the credit control client. It can be included in the Answer message even in case it is not present in the Request message. Alternatively the accounting interim interval can be omitted from the Answer message. However, since interim records are also produced at the expiry of granted service units and/or for mid-session service events the omission of Acct-Interim-Interval does not mean that interim records are not produced. During authorization, the authorization server MAY return the Accounting-Multi-Session-Id, which the Diameter credit control client MAY include in all subsequent accounting messages. The Accounting- Multi-Session-Id AVP MAY include the value of the original Session- Id. It's contents are implementation specific, but MUST be globally unique across other Accounting-Multi-Session-Id, and MUST NOT be changed during the life time of a credit control session. There are certain applications that require multiple accounting sub- sessions. Such applications would send messages with a constant Session-Id AVP, but a different Accounting Sub-Session-Id AVP. If several credit sub-sessions will be used, all sub-sessions MUST be closed separately before the closing the main session. The absence of this AVP implies no sub-sessions are in use. If the credit control client wants to perform credit-reservation before granting service to the end user it MUST use several interrogations towards the credit control server. In this case the credit control server MUST maintain the accounting session state. A one time event MAY be used when there is no need to maintain any state in the Diameter credit control server, for example enquiring the price of the service. 3.1 Session Based Credit Control For a session based credit control several interrogations are needed: the first, intermediate (optional) and the final interrogation. 3.1.1 First Interrogation Hakala et al. expires March 2003 [Page 8] INTERNET-DRAFT Diameter Credit Control Application November, 2002 The first interrogation MUST be sent before the Diameter credit control client in a service element allows any service event to the end user. The Accounting-Record-Type is set to the value START_RECORD in the first request message. The Subscription-Id-Data AVP SHOULD be included to identify the end-user in the credit control server. If the Diameter credit control client knows the cost of the service event 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 and the Service- Parameter-Info AVP SHOULD contain the service event information to be rated by the credit control server. The Service-Parameter-Info AVP always refers to the requested service units. The Event-Timestamp AVP contains the time when the service event is requested in the service element. 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 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 Accounting-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. However there MUST be maximum one instance of the same unit type in one Answer message. When the granted service units for one unit type have been spent a new Accounting-Request MUST be sent to the credit control server even though there would be service units left for other units types. The type of the Granted-Service-Unit AVP can be time, volume, service specific or money depending on the type of service event. It is not allowed to change the unit type(s) within the session. 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. service is free of charge) and terminate the credit control session. The Accounting-Answer message MAY also include the Final-Unit- Indication AVP to indicate that the Answer message contains the final units for the service session. After the end user has used these units, the Diameter credit control client is responsible for terminating the service session and the credit control session by sending the final interrogation to the credit control server. 3.1.2 Intermediate Interrogation Hakala et al. expires March 2003 [Page 9] INTERNET-DRAFT Diameter Credit Control Application November, 2002 When all the granted service units for one unit type are spent by the end user or the interim interval is expired the Diameter credit control client MUST send a new Accounting-Request to the credit control server. In case the Acct-Interim-Interval is used it is always up to the Diameter credit control client to send a new request well in advance before the expiration of the previous request in order to avoiding 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 accounting interim interval, the Diameter credit control client MUST send a new Accounting-Request to the credit control server. There can be also mid-session service events, which might affect the rating of the current service events. In this case a spontaneous updating (a new Accounting-Request) SHOULD be sent including information related to the service event even if all the granted service units have not been spent or the accounting interim interval 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 from the credit control server these units apply from the point where the measurement of the reported used units stopped. The Accounting-Record-Type AVP is set to the value INTERIM_RECORD in the intermediate request message. The Subscription-Id-Data AVP SHOULD also be included in the intermediate message to identify the end user in the credit control server. The Requested-Service-Unit AVP contains the new amount of requested service units. The Used-Service-Unit AVP contains the amount of used service units measured from the point when the service became active or, in case of interim interrogations are used during the session, from the point when the previous measurement ended. The same unit types that are used in the previous message MUST 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 contains the time of the event that triggered the sending of the new Accounting-Request. The credit control server MUST deduct the used monetary 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. The Accounting-Answer message with the Accounting-Record-Type AVP set to the value INTERIM_RECORD MAY include the Cost-Information AVP containing the accumulated cost estimation for the session without taking any credit-reservation into account. Hakala et al. expires March 2003 [Page 10] INTERNET-DRAFT Diameter Credit Control Application November, 2002 There MAY be several intermediate interrogations within a session. 3.1.3 Final Interrogation When the end user terminates the service session or when all the granted units are used after a Final-Unit-Indication AVP has been received from the credit control server, the Diameter credit control client MUST send a final Accounting-Request message to the credit control server. The Accounting-Record-Type AVP is set to the value STOP_RECORD. The Event-Timestamp AVP MAY contain the time of 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, in case of 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. The Accounting-Answer message with the Accounting-Record-Type set to the value STOP_RECORD SHOULD include the Cost-Information AVP containing the estimated total cost for the session in question. 3.1.4 Failure Procedures Since the credit control application is based on real-time bi- directional communication between the credit control client and the credit control server alternative destinations and buffering of messages are not sufficient in the event of communication failures. Since the credit control server has to maintain a session state the credit control message stream MUST not be moved to a backup credit control server during an ongoing credit control session. However, Diameter agents MAY perform failover to an alternative agent when they detect a transport failure. As a consequence the credit control server MAY 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 3.3), Session-Id AVP and Accounting-Record-Number AVP. If a communication failure occurs during an ongoing credit control session the credit control client will terminate or continue the service depending on the value set in the Credit-Control-Failure- Handling AVP. The Credit-Control-Failure-Handling AVP MAY be sent from the authorization server and in the Accounting-Answer from the credit control server. For new credit control sessions failover to alternative credit control server SHOULD be performed, if possible. Hakala et al. expires March 2003 [Page 11] INTERNET-DRAFT Diameter Credit Control Application November, 2002 The timer Tx (as defined in section 8) is used in the credit control client to supervise the communication with the credit control server. 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 Ts as defined in [DIAMBASE] is used in the credit control server. 3.2 One Time Event The one time event is used when there is no need to maintain accounting session state in the credit control server. The one time event can be used when the service element wants to know the cost of the service event without any credit-reservation or to check the account balance without any credit-reservation. It can be used also for refunding service units on the user's account or direct debiting without any credit-reservation. 3.2.1 Service Price Enquiry Sometimes the service element needs to know the price of the service event. There might exist services offered by application service providers, whose prices are not known in the service element. 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 Accounting-Record-Type AVP equal to EVENT_RECORD, include the Requested-Action AVP set to PRICE_ENQUIRY and set the requested service event information into the Service-Parameter-Info AVP in the Accounting-Request message. 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 price of the requested service event is returned to the credit control client in the Cost-Information AVP in the Accounting- Answer message. 3.2.2 Balance Check Sometimes Diameter credit control client needs only to verify that the end user's account balance covers the cost for a certain service without reserving any units from the account at the time of the enquiry. This method does not guarantee that there would be credit left when the Diameter credit control client requests the debiting of the account with a separate request. Hakala et al. expires March 2003 [Page 12] INTERNET-DRAFT Diameter Credit Control Application November, 2002 A Diameter credit control client requesting the balance check MUST set the Accounting-Record-Type AVP equal to EVENT_RECORD, include Requested-Action AVP set to CHECK_BALANCE and include the Subscription-Id-Data to identify the End-User in the credit control server. The credit control server makes the balance check, but it does not do any credit-reservation from the account. The result of balance check (Credit/No Credit) is returned to the credit control client in the Check-Balance-Result AVP in the Accounting-Answer message. 3.2.3 Direct Debiting There are certain one time events for which service execution is always successful in the service environment. Sometimes the delay between the service invocation and the actual service delivery to the end user can be so long that the use of the session based credit control would lead to unreasonable 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 will be successful, when this scenario is used. The Accounting-Record-Type is set to the value EVENT_RECORD and the Requested-Action AVP set to DIRECT_DEBITING in the Accounting-Request message. The Subscription-Id-Data AVP SHOULD be included to identify the End-User in the credit control server. The Event-Timestamp AVP contains the time when the service event is requested in the service element. The Diameter credit control client MAY include the monetary amount to be charged in the Request-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, then the Service-Parameter-Info AVP SHOULD contain the service event information to be rated by the credit control server. The Service-Parameter-Info AVP always refers to the requested service unit. The credit control server SHOULD rate the service event and deduct the corresponding monetary amount from 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 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. Hakala et al. expires March 2003 [Page 13] INTERNET-DRAFT Diameter Credit Control Application November, 2002 If the credit control server determines that no credit control is needed for the service it MAY include the result code indicating that the credit control is not applicable (e.g. service is free of charge). For informative purposes, the Accounting-Answer message SHOULD also include the Cost-Information AVP containing the estimated total cost of the requested service. 3.2.4 Refund There MAY be a need to refund service units on the end user's account, for example gaming services. The credit control client MUST set Accounting-Record-Type AVP to the value EVENT_RECORD and the Requested-Action AVP to REFUND in the Accounting-Request message. The Subscription-Id-Data AVP SHOULD be included to identify the End-User in the credit control server. The Diameter credit control client MAY include the monetary amount to be refunded in the Request-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, then the Service-Parameter-Info AVP SHOULD contain the service event information to be rated by the credit control server. The Service-Parameter-Info AVP always refers to the requested service unit. For informative purposes, the Accounting-Answer message MAY also include the Cost-Information AVP containing the estimated monetary amount of refunded unit. 3.2.5 Failure Procedure There MAY exist protocol transparent Diameter relays and redirect agents or Diameter credit control proxies between credit control client and credit control server. These agents MAY perform failover procedures if they detect transport failure as described in [DIAMBASE]. When the credit control client detects a communication failure to the credit control server its behavior depends on the requested action. The timer Tx (as defined in section 8) is used in the credit control client to supervise the communication with the credit control server. In case the requested action is Service Price Enquiry or Balance Check and communication failure is detected the credit control client MAY forward the request messages to an alternative credit control server, if possible. If the requested action is DIRECT_DEBITING and the Direct-Debiting- Failure-Handling AVP is set to TERMINATE_OR_BUFFER the credit control client SHOULD terminate the service if it can determine from the result code or error code in the answer message that units have not Hakala et al. expires March 2003 [Page 14] INTERNET-DRAFT Diameter Credit Control Application November, 2002 been debited. Otherwise the credit control client SHOULD grant the service to the end user and store the record in the credit control application level non-volatile storage. The credit control client MUST mark these request messages as possible duplicate 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 can't be delivered. If the timer Tx expires the credit control client MUST continue the service and eventually buffer the request according to the value of the Direct-Debiting-Failure-Handling AVP. The Accounting-Request with requested action REFUND 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 possible duplicate by setting the T-flag in the command header as described in [DIAMBASE] section 3. The implementation MAY choose to limit the number of re-transmission attempts and define a re-transmission interval. Because there can appear duplicate request for various reason the credit control server is therefore responsible for the real time duplicate detection. Implementation issues for duplicate detection are discussed in [DIAMBASE] Appendix C. When the credit control client re-sends messages from its application level non-volatile storage it MUST mark these request messages as possible duplicate by setting the T-flag in the command headers as described in [DIAMBASE] section 3. 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. In case when more than one credit control server are supporting the credit control application the accounting manager controlling the account database MAY be responsible for duplicate detection. 3.3 Credit Control Session State Machine The following state machines MUST be supported for credit control applications. The first two state machines are to be observed by credit control clients. The first one describes the session based credit control and the second one event based credit control. The third state machine describes the credit control session from a credit control server perspective. Any event not listed in the state machines MUST be considered as 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 Hakala et al. expires March 2003 [Page 15] INTERNET-DRAFT Diameter Credit Control Application November, 2002 Diameter credit control client is unable to communicate with the desired destination (i.e. the answer message is not received within the validity time of the request). This could be due to the peer being down, or due to a physical link failure in the path to/from the credit control server. The event 'Temporary error' means that the Diameter credit control client received a transient failure notification in the Accounting Answer command (i.e. the peer sending back a transient failure or temporary protocol error notification DIAMETER_TOO_BUSY, or DIAMETER_LOOP_DETECTED in the Result-Code AVP). The event 'Failed answer' means that the Diameter credit control client received non-transient failure (permanent failure) notification in the Accounting Answer command. The action 'store record' means that a record 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 unknown end user, account being empty or due to errors defined in [DIAMBASE]. The states PendingS, PendingI, PendingL PendingE and PendingB stand for pending states to wait for an answer to an accounting request related to a Start, Interim, Stop, Event or Buffered record respectively. CLIENT, SESSION BASED State Event Action New State --------------------------------------------------------------- Idle Client or device requests Send PendingS access accounting start req., start Tx. PendingS Successful accounting Stop Tx Open start answer received PendingS Failure to send, or Grant Idle temporary error and service to credit control fault end user handling equal to CONTINUE PendingS Failure to send, or Disconnect Idle temporary error and user/dev credit control fault handling equal to TERMINATE PendingS Tx expired and credit Disconnect Idle Control fault handling user/dev equal to TERMINATE Hakala et al. expires March 2003 [Page 16] INTERNET-DRAFT Diameter Credit Control Application November, 2002 PendingS Tx expired and credit control Grant fault handling equal to service to Idle CONTINUE end user PendingS Accounting start answer Disconnect Idle received with result code user/dev SERVICE_ DENIED or USER_NOT_FOUND PendingS Accounting start answer Grant Idle received with result code service equal to credit control N/A to end user PendingS Failed accounting start answer Grant Idle received and credit control Service to fault handling end user equal to CONTINUE PendingS Failed accounting start answer Disconnect Idle received and credit control user/dev failure handling equal to TERMINATE PendingS User service terminated Queue PendingS termination event PendingS Change in rating condition Queue PendingS changed rating condition event Open Granted unit elapses Send PendingI and no final unit accounting indication received interim req., start Tx. Open Granted unit elapses Disconnect PendingL and final unit indication send received accounting stop req., start Tx. Open Change in rating condition Send PendingI in queue accounting interim req., Start Tx. Open Service terminated in queue Send PendingL accounting Hakala et al. expires March 2003 [Page 17] INTERNET-DRAFT Diameter Credit Control Application November, 2002 stop req., start Tx Open Change in rating condition Send PendingI or interim interval elapses accounting interim req., Start Tx. Open User service terminated Send PendingL accounting stop req., start Tx PendingI Successful accounting interim Stop Tx Open answer received PendingI Failure to send, or Grant Idle temporary error and service to credit control fault end user handling equal to CONTINUE PendingI Failure to send, or Disconnect Idle temporary error and user/dev credit control fault handling equal to TERMINATE PendingI Tx expired and credit control Disconnect Idle fault handling equal to user/dev TERMINATE PendingI Tx expired and credit control Grant fault handling equal to service to Idle CONTINUE end user. PendingI Accounting interim answer Disconnect Idle received with result code user/dev SERVICE_DENIED PendingI Accounting interim answer Grant Idle received with result code service equal to credit control N/A to end user PendingI Failed accounting interim Grant Idle answer received and credit service to control fault handling equal end user. to CONTINUE PendingI Failed accounting interim Disconnect Idle answer received and credit user/dev control fault handling equal to TERMINATE Hakala et al. expires March 2003 [Page 18] INTERNET-DRAFT Diameter Credit Control Application November, 2002 PendingI User service terminated Queue PendingI termination event PendingI Change in rating Queue PendingI condition changed rating condition event PendingL Successful accounting stop Idle answer received PendingL Tx expired Idle PendingL Failure to send, or temporary Idle error or failed answer PendingL Change in rating condition PendingL CLIENT, EVENT BASED State Event Action New State ---------------------------------------------------------------- Idle Client or device requests Send PendingE a one-time service accounting event req., Start Tx. Idle Records in storage Send PendingB stored records PendingE Successful accounting Idle event answer received PendingE Failure to send, temporary Indicate Idle error or failed accounting service event answer received, or error Tx expired, requested action GET_BALANCE or PRICE_ENQUIRY PendingE Accounting event answer Disconnect Idle received with result code user/dev SERVICE_ DENIED or USER_NOT_FOUND PendingE Accounting event answer Grant Idle received with result code service credit control N/A, requested to end Hakala et al. expires March 2003 [Page 19] INTERNET-DRAFT Diameter Credit Control Application November, 2002 action DIRECT_DEBITING user PendingE Failure to send, temporary Grant Idle error or failed accounting service event answer received, or Tx to end expired, requested user action DIRECT_DEBITING and fault handling equal to CONTINUE PendingE Failed accounting event Disconnect Idle answer received, requested user/dev action DIRECT_DEBITING and fault handling equal to TERMINATE_OR_BUFFER PendingE Failure to send or Tx Grant Idle expired, requested service action DIRECT_DEBITING and to end user fault handling equal to and store TERMINATE_OR_BUFFER record with T-flag PendingE Temporary error, requested Disconnect Idle action DIRECT_DEBITING and user/dev fault handling equal to TERMINATE_OR_BUFFER PendingE Failed accounting event Indicate Idle answer received, requested service action REFUND error and delete record PendingE Failure to send or Store record Idle Tx expired, requested with T-flag action REFUND PendingE Temporary error Store record Idle and requested action REFUND PendingB Successful accounting answer Delete Idle received record PendingB Failed accounting answer Delete Idle received record PendingB Failure to send or Idle temporary error SERVER, SESSION AND EVENT BASED State Event Action New State Hakala et al. expires March 2003 [Page 20] INTERNET-DRAFT Diameter Credit Control Application November, 2002 ---------------------------------------------------------------- Idle Accounting start request Send Open received and successfully accounting processed. start answer, reserve units, start Ts Idle Accounting start request Send Idle received, but not accounting successfully processed. start Answer with Result-Code != SUCCESS Idle Accounting event request Send Idle received and successfully accounting processed. event answer, debit units Idle Accounting event request Send Idle received, but not accounting successfully processed. event Answer with Result-Code != SUCCESS Open Accounting Interim request Send Open received and successfully accounting processed answer, debit used units and reserve new units, Restart Ts Open Accounting interim request Send Idle received, but not accounting successfully processed. interim Answer with Result-Code != SUCCESS, debit used units Open Accounting stop request Send Idle received, and successfully accounting processed stop answer, Stop Ts, debit used Hakala et al. expires March 2003 [Page 21] INTERNET-DRAFT Diameter Credit Control Application November, 2002 units Open Accounting stop request Send Idle received, but not accounting successfully processed. stop Answer with Result-Code != SUCCESS, debit used units Open Session supervision timer Ts Stop Ts, Idle expired release reserved units 4 Accounting AVPs This section defines the accounting AVPs that are specific to Diameter Credit Control Application and MAY be included in the Diameter accounting messages [DIAMBASE]. Accounting-Request command MAY include the following additional AVPS: [ Subscription-Id ] [ Requested-Action ] *[ Requested-Service Unit ] *[ Used-Service-Unit ] *[ Service-Parameter-Info ] [ Abnormal-Termination-Reason] *[ Accounting-Correlation-Id ] [ Credit-Control-Failure-Handling ] Accounting-Answer command MAY include a following additional AVPS: [ Subscription-Id ] *[ Granted-Service-Unit ] [ Cost-Information] [ Final-Unit-Indication ] [ Check-Balance-Result ] [ Credit-Control-Failure-Handling ] The following table describes the Diameter AVPs defined in Credit Control application, their AVP Code values, types, possible flag values and whether the AVP MAY be encrypted. +---------------------+ | AVP Flag rules | |----+-----+----+-----|----+ AVP Section | | |SHLD| MUST|MAY | Attribute Name Code Defined Data Type |MUST| MAY | NOT| NOT|Encr| -----------------------------------------|----+-----+----+-----|----| Abnormal- XXX 4.1 Enumerated | M | P | | V | Y | Termination-Reason | | | | | | Hakala et al. expires March 2003 [Page 22] INTERNET-DRAFT Diameter Credit Control Application November, 2002 Accounting- XXX 4.2 OctetString| M | P | | V | Y | Correlation-Id | | | | | | Check-Balance- XXX 4.3 Enumerated | M | P | | V | Y | Result | | | | | | Cost-Information XXX 4.5 Grouped | M | P | | V | Y | Credit-Control- XXX 4.6 Enumerated | M | P | | V | Y | Failure-Handling | | | | | | Direct-Debiting XXX 4.8 Enumerated | M | P | | V | Y | Failure-Handling | | | | | | Final-Unit- XXX 4.9 Unsigned32 | M | P | | V | Y | Indicator | | | | | | Granted-Service- XXX 4.10 Grouped | M | P | | V | Y | Unit | | | | | | Requested-Action XXX 4.11 Enumerated | M | P | | V | Y | Requested-Service XXX 4.12 Grouped | M | P | | V | Y | Unit | | | | | | Service-Parameter XXX 4.14 Grouped | M | P | | V | Y | Info | | | | | | Subscription-Id XXX 4.17 Grouped | M | P | | V | Y | Used-Service-Unit XXX 4.22 Grouped | M | P | | V | Y | -----------------------------------------+----+-----+----+-----+----+ 4.1 Abnormal-Termination-Reason AVP The Abnormal-Termination-Reason AVP (AVP Code TBD) is of type Enumerated and contains information about the reason for an abnormal service termination in a service element. The following reasons are defined: SERVICE_ELEMENT_TERMINATION 0 An error occurred in the service element. CONNECTION_TO_END-USER_BROKEN 1 The connection to the end-user is broken. 4.2 Accounting-Correlation-Id AVP The Accounting-Correlation-Id AVP (AVP Code TBD) is type of OctetString and contains information to correlate accounting data generated for different components of the service, e.g. transport and service level. 4.3 Check-Balance-Result AVP The Check Balance Result AVP (AVP code TBD) 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 Accounting-Request command. The following values are defined for the Check-Balance-Result AVP. ENOUGH_CREDIT 0 Hakala et al. expires March 2003 [Page 23] INTERNET-DRAFT Diameter Credit Control Application November, 2002 There is enough credit in the account to cover the requested service. NO_CREDIT 1 There isnÆt enough credit in the account to cover the requested service. 4.4 Cost-Information AVP The Cost-Information AVP (AVP Code TBD) is of type Grouped and is used to return the cost information of a service in the Accounting- Answer command. The included Unit-Value AVP contains the cost estimate (always type of money) of the service in 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. When the Requested-Action AVP with value PRICE_ENQUIRY is included in the Accounting-Request command the Cost-Information AVP sent in the succeeding Accounting-Answer command contains the cost estimation of the requested service, without any reservation being made. The Cost-Information AVP included in the Accounting-Answer command with the Accounting-Record-Type set to INTERIM_RECORD contains the accumulated cost estimation for the session without taking any credit-reservation into account. The Cost-Information AVP included in the Accounting-Answer command with the Accounting-Record-Type set to EVENT_RECORD or STOP_RECORD contains the estimated total cost for the requested service. It has the following ABNF grammar: ::=< AVP Header: TBD > { Unit-Value } { Currency-Code } 4.5 Credit-Control-Failure-Handling AVP The Credit-Control-Failure-Handling AVP (AVP Code TBD) is of type Enumerated. The credit control client uses information in this AVP to decide what to do if the sending of credit control messages to the credit control server has been for instance temporarily prevented due to a network problem. TERMINATE 0 When the Credit-Control-Failure-Handling AVP is set to TERMINATE the service MUST only be granted as long as there is a connection to the credit control server. If the credit control client does not receive any Accounting-Answer message within the Tx timer (as defined in section 8) the credit control request is regarded failed. The moving of already started credit control session to alternative server is not allowed. Hakala et al. expires March 2003 [Page 24] INTERNET-DRAFT Diameter Credit Control Application November, 2002 This is the default behaviour 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 service SHOULD be granted even if credit control messages can't be delivered. 4.6 Currency-Code AVP The Currency-Code AVP (AVP Code TBD) 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 using the numeric values defined in the ISO 4217 standard. 4.7 Direct-Debiting-Failure-Handling AVP The Direct-Debiting-Failure-Handling AVP (AVP Code TBD) is of type Enumerated. The credit control client uses information in this AVP to decide what to do if the sending of 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 as long as there is a connection to the credit control server. If the credit control client does not receive any Accounting-Answer message within the Tx timer (as defined in section 8) the credit control request is regarded 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 to application level non-volatile storage and try to re-send the request. These requests MUST be marked as possible duplicate by setting the T- flag in the command header as described in [DIAMBASE] section 3. This is the default behaviour 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. 4.8 Exponent AVP Exponent AVP is of type Integer32 (AVP code TBD) and contains the exponent value to be applied for the Value-Digit AVP within the Unit- Value AVP. Hakala et al. expires March 2003 [Page 25] INTERNET-DRAFT Diameter Credit Control Application November, 2002 4.9 Final-Unit-Indication AVP The Final-Unit-Indication AVP (AVP Code TBD) is of type Unsigned32 and indicates that the Granted-Service-Unit AVP in the accounting command contains the final units for the service. After these units have expired, the Diameter credit control client in a service element is responsible for terminating the service and sending the STOP_RECORD to the credit control server. If more than one unit types are received in the Accounting-Answer, the Unit type which first expired SHOULD cause the termination. If included in a command, the value of this AVP is always 1. 4.10 Granted-Service-Unit AVP Granted-Service-Unit AVP (AVP Code TBD) 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 Accounting-Request must be sent. The Unit-Value AVP contains the granted units and the Unit-Type AVP defines the type of the unit. If the Unit-Type AVP is set to time in the Accounting-Answer command, the Unit Value AVP specifies the granted time in seconds. If the Unit-Type AVP is set to volume in the Accounting-Answer command, the Unit-Value AVP specifies the granted volume in bytes. If the Unit-Type AVP is set to service specific in the Accounting- Answer command, the Unit-Value AVP specifies the granted number of service specific units (e.g. number of events, points) given in a selected service. If the Unit-Type AVP is set to money in the Accounting-Answer command, the Unit-Value AVP specifies the granted monetary amount in the given currency. If the unit type is money, a Currency-Code AVP SHOULD be included. It has the following ABNF grammar: ::=< AVP Header: TBD > { Unit-Type } { Unit-Value } [ Currency-Code ] 4.11 Requested-Action AVP The Requested-Action AVP (AVP Code TBD) is type of Enumerated and contains the requested action being sent by Accounting-Request command where the Accounting-Record-Type is set to EVENT_RECORD. The following values are defined for the Requested-Action AVP: DIRECT DEBITING 0 Hakala et al. expires March 2003 [Page 26] INTERNET-DRAFT Diameter Credit Control Application November, 2002 Direct debiting indicates that the request is to decrease the end user's account according to information specified in the Requested-Service-Unit AVP and/or Service-Parameter-Info AVP. The Granted-Service Unit AVP in the Accounting-Answer command contains the debited units. REFUND ACCOUNT 1 Refund account indicates that the request is to increase the end user's account according to information specified in the Requested-Service-Unit AVP and/or Service-Parameter-Info AVP. The Granted-Service Unit AVP in the Accounting-Answer command contains the refunded units. CHECK_BALANCE 2 Check balance indicates that the request is 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 Accounting-Answer command contains the result of the Balance Check. PRICE_ENQUIRY 3 Price Enquiry indicates that the request is 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 Accounting-Answer Command. 4.12 Requested-Service-Unit AVP The Requested-Service-Unit AVP (AVP Code TBD) is of type Grouped and contains the amount of requested units specified by the Diameter credit control client. The included Unit-Value AVP contains the requested Unit-Value and the Unit-Type AVP defines the type of the unit. If the Unit Type AVP is set to time in the Accounting-Request command, the Unit-Value AVP specifies the requested time in seconds. If the Unit-type AVP is set to volume in the Accounting-Request command, the Unit-Value AVP specifies the requested volume in bytes. If the Unit-type AVP is set to service specific in the Accounting- Request command, the Unit-Value AVP specifies the used number of service specific units (e.g. number of events) given in a selected service. If the Unit-Type AVP is set to money in the Accounting-Request command, the Unit-Value AVP specifies the monetary amount in the given currency. If the unit type is money, a Currency-Code AVP SHOULD be included. It has the following ABNF grammar: Hakala et al. expires March 2003 [Page 27] INTERNET-DRAFT Diameter Credit Control Application November, 2002 ::=< AVP Header: TBD > { Unit-Type } { Unit-Value } [ Currency-Code ] 4.13 Service-Parameter-Info AVP The Service-Parameter-Info AVP (AVP Code TBD) is of type Grouped and contains a 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. Alternatively it MAY also contain IANA registered standard AVPs or vendor specific AVPs. The actual contents of these AVPs are not within the scope of this document and SHOULD be defined in another Diameter application, standards written by other standardization bodies, or service specific documentation. In case of unknown service request (e.g. unknown AVP or Service- Parameter-Type), the corresponding answer message MUST contain error code DIAMETER_AVP_UNSUPPORTED or DIAMETER_INVALID_AVP_VALUE. An Accounting Answer message with these errors MUST contain one or more FAILED-AVP AVPs containing the AVPs that caused the failure. It has the following ABNF grammar: ::=< AVP Header: TBD > [ Service-Parameter-Type ] [ Service-Parameter-Value ] [ AVP ] 4.14 Service-Parameter-Type AVP The Service-Parameter-Type AVP is of type Unsigned32 (AVP Code TBD) and defines the type of the service event specific parameter (e.g. it can be end-user location, service name). The different parameters and their types are service specific and the meanings of these parameters are not defined in this document. The Service-Parameter-Value AVP contains the service parameter type. 4.15 Service-Parameter-Value AVP The Service-Parameter-Value AVP is of type UTF8String (AVP Code TBD) and contains the value of the service parameter type. 4.16 Subscription-Id AVP The Subscription-Id AVP (AVP Code TBD) is used to identify the end userÆs subscription and is of type Grouped. The Subscription-Id AVP includes a Subscription-Id-Data AVP that hold the identifier and a Subscription-Id-Type AVP that defines the identifier type. It has the following ABNF grammar: Hakala et al. expires March 2003 [Page 28] INTERNET-DRAFT Diameter Credit Control Application November, 2002 ::=< AVP Header: TBD > { Subscription-Id-Data } { Subscription-Id-Type } 4.17 Subscription-Id-Data AVP The Subscription-Id-Data AVP (AVP Code TBD) is used to identify the end-user and is of type UTF8String. The Subscription-Id-Type AVP defines which type of identifier is used. 4.18 Subscription-Id-Type AVP The Subscription-Id-Type AVP (AVP Code TBD) is of type Enumerated and it is used to determine which type of identifier that is carried by the Subscription-Id AVP. The identifier can be one of the following: END_USER_MSISDN 0 The identifier is in international MSISDN format, according to the ITU-T E.164 numbering plan as 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 [E121] and [CE121]. END_USER_SIP_URL 2 The identifier is in the form of a SIP URL as defined in [SIP]. END_USER_NAI 3 The identifier is in the form of a Network Access Identifier as defined in [NAI]. END_USER_PRIVATE 4 The Identifier is a credit control server private identifier. 4.19 Unit-Type AVP The Unit-Type AVP is of type Enumerated (AVP Code TBD) and contains the type of the unit. The unit type can be one of the following: CREDIT_TYPE_TIME 0 The unit is of type time, given in seconds. CREDIT_TYPE_VOLUME 1 The unit is of type volume, given in bvtes. Hakala et al. expires March 2003 [Page 29] INTERNET-DRAFT Diameter Credit Control Application November, 2002 CREDIT_TYPE_SERVICE_SPECIFIC 2 The unit is service specific (e.g. number of events, points, chips, services etc), given in a selected service. CREDIT_TYPE_MONEY 3 The unit is of type money, given as a monetary value, whose currency SHOULD be specified by the Currency-Code AVP. 4.20 Unit-Value AVP Unit-Value AVP is of type Grouped (AVP Code TBD). The value can be time in seconds, volume in bytes, number of service specific units or monetary amount depending on the given unit type. The Unit-Value is a value together 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 exponent part MUST be interpreted as exponent being equal to zero. It has the following ABNF grammar: ::=< AVP Header: TBD > { Value-Digits } [ Exponent ] 4.21 Used-Service-Unit AVP The Used-Service-Unit AVP is of type Grouped AVP (AVP Code TBD) and contains the amount of used units measured from the point when the service became active or, in case of interim interrogations are used during the session, from the point when the previous measurement ended. The included Unit-Type AVP defines the type of the unit and the Unit-Value AVP contains the used amount. If the Unit Type AVP is set to time in the Accounting-Request command, the Unit-Value AVP specifies the used time in seconds. If the Unit-Type AVP is set to volume in the Accounting-Request command, the Unit-Value AVP specifies the used volume in bytes. If the Unit-type AVP is set to service specific in the Accounting- Request command, the Unit-Value AVP specifies the used number of service specific units (e.g. number of events) given in a selected service. If the Unit-Type AVP is set to money in the Accounting-Request command, the Unit-Value AVP specifies the used monetary amount in the given currency. If the unit type is money, a Currency-Code AVP SHOULD be included. It has the following ABNF grammar: Hakala et al. expires March 2003 [Page 30] INTERNET-DRAFT Diameter Credit Control Application November, 2002 ::=< AVP Header: TBD > { Unit-Type } { Unit-Value } [ Currency-Code ] 4.22 Value-Digits AVP The Value-Digits AVP is of type Unsigned64 (AVP code TBD) and contains the number of seconds, volume in bytes, number of service specific units or monetary amount depending on the given Unit-Type AVP. 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 û2. 5 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 Accounting-Answer message includes the Result-Code AVP, which MAY indicate that an error was present in the Accounting-Request message. A rejected Accounting-Request message SHOULD cause the userÆs session to be terminated. 5.1 Transient Failure 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 MAY be able to satisfy the request in the future. DIAMETER_END_USER_SERVICE_DENIED 40XX The credit control server denies the service request due to service restrictions or limitations related to the end-user, for example the end-user's account could not cover the requested service. DIAMETER_CREDIT_CONTROL_NOT_APPLICABLE 40XX The credit control server determines that the service can be granted to the end user but no further credit control is needed for the service (e.g. service is free of charge). 5.2 Permanent Failures Errors that fall within permanent failure category are used to inform the peer that the request failed, and should not be attempted again. DIAMETER_USER_UNKNOWN 50XX The specified end user is unknown in the credit control server. 6 AVP Occurrence Table Hakala et al. expires March 2003 [Page 31] INTERNET-DRAFT Diameter Credit Control Application November, 2002 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 are more than once 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. 6.1 Accounting 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 accounting messages. +-----------+ | Command | | Code | |-----+-----+ Attribute Name | ACR | ACA | ------------------------------|-----+-----+ Abnormal-Termination-Reason | 0-1 | 0 | Accounting-Correlation-Id | 0-1 | 0 | Credit-Control-Failure- | 0-1 | 0-1 | Handling | | | Check-Balance-Result | 0 | 0-1 | Cost-Information | 0 | 0-1 | Direct-Debiting-Failure- | 0 | 0 | Handling AVP | | | Final-Unit-Indication | 0 | 0-1 | Granted-Service-Unit | 0 | 0+ | Requested-Action | 0-1 | 0 | Requested-Service-Unit | 0-1 | 0 | Service-Parameter-Info | 0+ | 0 | Subscription-Id | 0-1 | 0-1 | Used-Service-Unit | 0+ | 0 | ------------------------------|-----+-----+ 7 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. 7.1 Application Identifier Hakala et al. expires March 2003 [Page 32] INTERNET-DRAFT Diameter Credit Control Application November, 2002 This specification assigns the value TBD to the Application Identifier namespace defined in [DIAMBASE]. See section 1.3 for more information. 7.2 Command Codes This specification uses the value 271 from the Command code namespace defined in [DIAMBASE]. 7.3 AVP Codes This specification assigns the values TBD - TBD from the AVP code namespace defined in [DIAMBASE] See section 4.0 for the assignment of the namespace in this specification. 7.4 Result-Code AVP Values This specification assigns the values 40XX and 50XX from the Result- Code AVP (AVP Code 268) value namespace defined in [DIAMBASE]. See section 5.0 for the assignment of the namespace in this specification. 7.5 Abnormal-Termination-Reason AVP As defined in Section 4.1, the Abnormal-Termination-Reason AVP (AVP Code TBD) defines the values 0-1. All remaining values are available for assignment via Designated Expert [IANA]. 7.6 Check-Balance-Result AVP As defined in Section 4.3, the Check-Balance-Result AVP (AVP Code TBD) defines the values 0-1. All remaining values are available for assignment via Designated Expert [IANA]. 7.7 Credit-Control-Failure-Handling AVP As defined in Section 4.6, the Credit-Control-Failure-Handling AVP (AVP Code TBD) defines the values 0-1. All remaining values are available for assignment via Designated Expert [IANA]. 7.8 Direct-Debiting-Failure-Handling AVP As defined in Section 4.8, the Direct-Debiting-Failure-Handling AVP (AVP Code TBD) defines the values 0-1. All remaining values are available for assignment via Designated Expert [IANA]. 7.9 Requested-Action AVP As defined in Section 4.11, the Requested-Action AVP (AVP Code TBD) defines the values 0-3. All remaining values are available for assignment via Designated Expert [IANA]. Hakala et al. expires March 2003 [Page 33] INTERNET-DRAFT Diameter Credit Control Application November, 2002 7.10 Subscription-Id-Type AVP As defined in Section 4.17, the Subscription-Id-Type AVP (AVP Code TBD) defines the values 0-4. All remaining values are available for assignment via Designated Expert [IANA]. 7.11 Unit-Type AVP As defined in Section 4.20, the Unit-Type AVP (AVP Code TBD) defines the values 0-3. All remaining values are available for assignment via Designated Expert [IANA]. 8 Credit Control Application related parameter Tx timer When real-time credit control is required, the credit control client contacts the credit control server before and during the service is provided to an end user. Due to real-time nature of application the communication delays SHOULD be minimized, e.g. to avoid too long service set up time experienced by the end user. The Tx timer is introduced to control the waiting time in the client in the PENDING state. The recommended value is 10 seconds. 9 Security Considerations The security models as defined in the Diameter base protocol [DIAMBASE] applies to this application too. 10 References 10.1 Normative [DIAMBASE] P. Calhoun, J. Arkko, E. Guttman, G. Zorn, J. Loughney "Diameter Base Protocol", draft-ietf-aaa-diameter-15.txt, IETF work in progress, June 2002. [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] M. Handley, H. Schulzrinne, E. Schooler, J. Rosenberg, G. Camarillo, A. Johnston, J. Peterson, R. Sparks "SIP: Session Initiation Protocol", RFC 3261. June 2002. [NAI] Aboba, Beadles "The Network Access Identifier." RFC 2486. January 1999. [E164] Recommendation E.164/I.331 (05/97): The International Public Telecommunication Numbering Plan. 1997. Hakala et al. expires March 2003 [Page 34] INTERNET-DRAFT Diameter Credit Control Application November, 2002 [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, Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998 10.2 Non-Normative [KEYWORDS] S.Bradner, "Key words for use in RFCs to Indicate Requirement Levelsö, BCP 14, RFC 2119, March 1997. [ACCMGMT] B.Aboba, J.Arkko, D.Harrington. "Introduction to Accounting Management", RFC 2975, October 2000. 11 Acknowledgement The authors would like to thank Paco Marin at Vodafone R&D and our colleagues with Ericsson and Nokia for their comments and suggestions. 12 Author's Address Harri Hakala Oy L M Ericsson Ab Joukahaisenkatu 1 20520 Turku Finland Phone: +358 2 265 3722 EMail: Harri.Hakala@ericsson.fi Leena Mattila Oy L M Ericsson Ab Joukahaisenkatu 1 20520 Turku Finland Phone: +358 2 265 3731 EMail: Leena.Mattila@ericsson.fi Juha-Pekka Koskinen Nokia Networks Hatanpaanvaltatie 30 Hakala et al. expires March 2003 [Page 35] INTERNET-DRAFT Diameter Credit Control Application November, 2002 33100 Tampere Finlad Phone: +358 7180 74027 Email: juha-pekka.koskinen@nokia.com Marco Stura Nokia Networks Valimotie 21 00380 Helsinki Phone: +358 7180 64308 Email: marco.stura@nokia.com 13 Full Copyright Statement Copyright (C) The Internet Society (2002). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this docu- ment itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. 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