CPC overview
Converged Policy and Charging (CPC) is a cloud-native network function (CNF) that provides unified, 3GPP-compliant policy control for both 4G and 5G networks. It integrates subscriber authentication, authorization, accounting (AAA), and policy management into a single, streamlined solution.
Benefits:
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Simplified Migration: CPC eliminates the need for manual migration of user subscriptions or reconfiguration of policy and charging functions (CPC) during the transition from 4G to 5G.
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Reduced Network Complexity: It supports incremental deployment of Standalone (SA) 5G networks by removing the requirement for complex inter-circle mesh connectivity, thus facilitating smoother network evolution.
System Composition:
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CPC offers a containerized, cloud-native architecture based on a three-tier microservices framework.
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It supports AAA components using Diameter servers for subscriber management, with protocol, service, and session tiers managing authentication, authorization, accounting, and data persistence.
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The solution includes operational tools such as Policy Builder and Ops-Center for configuration and management, integrated with Cisco Cloud Native Data Plane (CNDP) services for logging, metrics, and alerts.
CPC architecture
The CPC architecture is built on a multi-layer platform, which enables efficient policy control and management in the 5G Core network.
At a high level, the components in the architecture perform the following:
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External Endpoint
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REST-EP—It is a RESTful interface, which provides a channel for the 5G inbound and outbound messages.
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LDAP-EP, UAPI, and CRD API—Provides interfaces for CPC communications.
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Diameter-EP—Responsible for routing the Diameter traffic.
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Processing Layer
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grPC—Provides a framework that enables the internal processes to communicate with each other and synchronize their events.
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CPC-Engine—Hosts the business logic of CPC and responsible for driving the rules engine for making crucial policy decisions.
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Configurations
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Policy Builder—Allows configuration of the CPC cluster of virtual machines (VMs) and configuration of services and advanced policy rules.
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CPC Central—Provides a unified GUI that allows you to configure Policy Builder, manage custom reference table data, and start the Web-based applications and utilities.
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Ops Center—Allows you to configure and manage the applications and pods configuration.
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Storage Layer
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Binding Database Client—Provisions the client to look up the PCRF Mongo Binding Database for information about the secondary key lookup across 4G and 5G.
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MongoDB—Preserves the subscriber-specific, balance data, and admin configuration data.
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Session store—Contains the data which CDL accesses for processing a session persistence activity. Stores the CPC sessions.
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Etcd—Contains the Diameter endpoint configurations.
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CPC deployment
The CPC reduces the deployment complexity by integrating CPC and PCF in a unified environment.
This figure illustrates the CPC deployment.
The CPC deployment architecture includes:
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One Region = Two sites. Each site has one cluster (total two clusters in a region).
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Noncloud-native deployment along with cloud-native 5G CPC.
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External binding database is the local database for PCRF.
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MongoDB is the dedicated session database for PCRF.
The CPC's deployment architecture includes:
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One Region = Two sites. Each site has one cluster (total two clusters in a region).
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Cloud-native deployment that deployed along with 4G PCRF.
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Cisco CDL is the dedicated session database for CPC.
Supported Interfaces
CPC and other NFs in 5GC use these:
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Rx– Reference point for interworking with AF, PCRF, and CPC
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N5– Reference point between CPC and AF
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N7– Reference point between CPC and SMF
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N15– Reference point between CPC and AMF
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N28– Reference point between CPC and CHF
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N36– Reference point between CPC and UDR
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LDAP– Reference point between CPC and external subscriber profile
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