PCC Solution Overview
This section provides an overview of the Tango iAX PCC solution. The main components of the iAX PCC are described along with the main interfaces that make up the iAX PCC solution. The visual above shows an overview of the Tango iAX PCC solution.
PCRF
The PCRF performs the core function of generating rules that enforce policy and charging control on a PCEF. The PCRF contains a diameter stack which supports a Gx interface for interaction with a third-party PCEF and an Rx interface for Application Functions (e.g. VoIP call-session controller).
The PCRF service logic is called when a user initiates a data-session on their handset. The service logic controls the generation of policy and charging control rules for the PCEF data-session based on the following set of inputs:
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Parameters received from the PCEF over the Gx interface.
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Parameters received from an Application Function (AF) over the Rx interface.
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Subscriber profile information received from the SPCM or a third-party SPR.
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PCRF rules data which has been configured in the PCC database.
In addition to this, the PCRF service logic also performs the following functions:
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Manages the PCEF usage-monitors and passes usage information from PCEF usage reports to the SPCM.
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Manages PCEF event triggers such as location change and provides PCC rules updates to the PCEF for event reports.
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Manages asynchronous notifications from the SPCM or a third-party SPR and provides PCC rules updates to the PCEF for subscriber profile changes.
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Manages asynchronous notifications from application functions and provides PCC rules updates to the PCEF for application sessions.
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Manages time-bands and provides PCC rules updates to the PCEF for time-band transitions.
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Provides default rules to the PCEF if the subscriber profile information is not available from the SPCM or third-party SPR.
Subscriber Policy and Charging Manager
The Subscriber Policy and Charging Manager (SPCM) manages subscriber data plans and notifies the PCRF if a policy or charging control change is required. Subscriber provisioning is also managed in the SPCM.
The SPCM has an Sp interface with the PCRF which is used to carry out the following:
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Provide the PCRF with subscriber profile information at the start of a session.
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Provide the PCRF with usage-tracking parameters and process the subsequent usage reports received from the PCRF.
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Notify the PCRF of subscriber profile changes, e.g. due to the data-usage threshold being exceeded or data plan expiry.
Data usage may be tracked for a subscriber’s core data plan and for any additional active data plans they may have. Furthermore, usage may be categorised by time-band (e.g. Peak/Off-Peak), location (e.g. Home/Roaming) or APN. The SPCM may perform the following actions if total data-usage or a usage category exceeds a configured threshold value:
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Notify the PCRF to change policy and/or charging control for data-sessions.
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Send an SMS notification to the subscriber.
The SPCM contains a subscriber self-care function to allow subscribers to purchase data plans, manage multiple data plans and view usage information.
The SPCM uses the Tango Open Charging Interface (OCI) server to charge for the data plans which are purchased by subscribers. The OCI server can be configured to use a specific online charging protocol as required by the third-party Online Charging System (OCS).
An API is also provided for third-party provisioning platforms to create and update subscribers in the Tango PCC database.
The SPCM can run in an active or passive mode, as determined by configuration settings at startup. When in active mode the SPCM behaves as usual. When in passive mode the SPCM does the following:
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Ceases to execute jobs.
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Removes itself from the resource manager.
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The web service only accepts GET requests and OAM POST requests.
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Ceases to process received SE messages.
Diameter Routing Agent
The Diameter Routing Agent (DRA) ensures that all Diameter sessions established over the Gx and Rx interfaces reach the correct PCRF when multiple, separately addressable PCRF’s have been deployed in a Tango iAX PCC cluster. This effectively provides scalability and high availability to the Tango iAX PCC platform.
Open Charging Interface Server
The Open Charging Interface (OCI) server provides an IDL to the SPCM to charge for data plans which are purchased by subscribers via one of the self-care interfaces or by a customer care agent via the PMI.
The OCI server can be configured to use one of the many Tango charging clients depending on which protocol is required by the third-party Online Charging System (OCS) e.g. Diameter Credit-Control (DCC).
The OCI server may be configured to use an event-based (i.e. direct-debit) or session based (i.e. reserve & debit) charging process as required by the third-party OCS for data plan charging.
iAX PCC Databases
The PCC database is a highly-available MySQL database that provides persistent data storage for the following Tango iAX PCC software modules:
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PCRF rules handler
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SPCM
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PMI
Depending on the hardware configuration of your network, the PCC database may be deployed on separate nodes at the back-end of the iAX PCC platform or on iAX PCC platform nodes.
The PCC database uses a master-slave configuration with replication and logical IP management in order to ensure that the PCC database is highly available.
Platform Management Interface GUI
The Platform Management Interface (PMI) is a web application which provides a graphical user interface (GUI) to manage subscribers and their data plans and to configure the policy and charging control information for subscriber data plans.
The Policy section of the PMI allows you to carry out the following specific functions:
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Data plan creation and management.
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Data plan categorisation.
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Subscriber creation and management.
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Configuration of the following low-level PCRF parameters which are used to generate policy and charging control rules:
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IP filter lists
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QoS parameters
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Charging parameters and rating group tables
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Location lists
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Time bands
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APN lists
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Application policy information
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Display O&M information for the iAX PCC platform