PCF Architecture
The PCF 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 PCF 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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PCF-Engine—Hosts the business logic of PCF 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 PCF cluster of virtual machines (VMs) and configuration of services and advanced policy rules.
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PCF Central—Provides a unified GUI that allows you to configure Policy Builder, manage custom reference table data, and initiate 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 PCF sessions.
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Etcd—Contains the Diameter endpoint configurations.
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