Diameter is an authentication, authorization, and accounting protocol for computer networks. The Diameter base protocol is defined by RFC ( Obsoletes: RFC ) and CCR, , Diameter Credit-Control Application – RFC Diameter Credit-Control Application, is a networking protocol for Diameter application used to implement real-time credit-control for a variety of end user services. It is an IETF standard defined in RFC RFC (part 1 of 5): Diameter Credit-Control Application. Network Working Group H. Hakala Request for Comments: L. Mattila Category: Standards.
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Network Working Group H. Hakala Request for Comments: Standards Track Ericsson J-P. Loughney Nokia August 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 diametwr.
Distribution of this memo is unlimited. 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 diametr services. Table of Contents 1.
Service-Specific Rating Input and Interoperability Credit-Control Application State Machine Credit-Control Application Related Parameters Direct Connection with Redirects 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. 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 doameter 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.
To fulfill these requirements, it is necessary to facilitate credit- control communication between the network element providing the service e. The scope of this specification is the credit authorization. Service specific authorization and authentication is out of the scope. AA answer commands are defined in service specific authorization applications, e.
AA request AA request generically refers to a service specific authorization and authentication request. AA request commands are defined in service specific authorization diamteer e. 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 rdc 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. 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.
RFC – part 1 of 5
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. 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. In the latter case, the interface between the Service Element and the Diameter credit- control client is outside the scope of this specification. Service Event An event relating to a service provided to the end user. Session based credit-control A credit-control process that makes use of several interrogations: 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.
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. 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 viameter 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.
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 diametet entities.
Diameter Credit-Control Application – Wikipedia
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. 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.
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 sand 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. 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. 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.
The Command Codes are as follows: These formats are observed in Credit-Control messages. It is used between the Diameter credit-control client and the credit-control server to request credit authorization for a given service.
It is used between the credit-control server and the Diameter credit-control client to acknowledge a Credit- Control-Request command. 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: In both models, the credit- control client diametfr credit authorization from the credit-control server prior diameteer 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.
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. Alternatively, during an active multimedia session, an additional media type is added to diameteg 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 diameher time event. 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.
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.