Binding Support Function (BSF)

Scale your 5G policy and charging architecture with the BroadForward BSF. Built in accordance with the 3GPP TS 29.521 specifications, the BroadForward Binding Support Function operates as the centralized intelligence layer for correlating and resolving all policy‑related bindings in a 5G Standalone core. The BSF ensures that every AF, NEF, or internal 5G NF consistently reaches the correct PCF instance for each active session, delivering predictable policy behavior, reduced signaling complexity, and scalable 5G SA deployments. Built on the BroadForward BFX Unified Signaling Core (USC), the BSF acts as the authoritative binding engine for HTTP/2, continuously tracking relationships between PDU sessions, subscriber identities (SUPI, GPSI), addressing information (IPv4/IPv6), and session attributes (DNN, S‑NSSAI). This gives operators precise, real‑time control over policy binding and guarantees reliable policy enforcement across the entire 5G core.

Deployment options:

Bare metal
Virtual machine
Container
Cloud

Features:

GUI based configuration management
Policy session management for N24/N7
Supports all relevant 5G interface that requires session management via Nbsf binding lookup (N7/N24, AF/NEF)
High performance internal in memory database
Selective Ingress Throttling for congestion control and prioritization
Highly configurable, no scripting or coding
Subscribe/Notify support for binding lifecycle events

Foundation

The BroadForward BSF in your Network

The BroadForward Binding Support Function (BSF) provides a centralized intelligence layer for correlating and resolving all policy‑related bindings in a 5G Standalone core, optionally co-hosted with the BroadForward SCP. It acts as the authoritative discovery point that ensures every network function – AF, NEF, and internal 5G NFs – consistently reaches the correct PCF instance for each active session. Built on the BFX Unified Signaling Core platform, the BSF serves as the 5G evolution of the 4G Session Binding Function, continuously tracking and storing relationships between PDU sessions, subscriber identities (SUPI, GPSI), addressing information (IPv4/IPv6), and session attributes (DNN, S‑NSSAI). This gives operators precise, real‑time control over policy binding, enabling predictable, reliable policy enforcement across the entire 5G core.

Years of BFX USC in production

Operators running BFX USC

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GSMA GLOMO winner

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Multi-tenancy

Unifying Policy & Routing: Co-Hosting with the BroadForward SCP

Every BroadForward product runs on the BFX USC - one engine, one operational model. The BSF can be co hosted directly with the BroadForward Service Communication Proxy (SCP), using the same GUI, workflows, and operational environment. When co‑located with the BroadForward SCP, binding lookups are executed locally using an in‑memory database that is synchronized across all SCP/BSF nodes and across sites. This design reduces internal SBI signaling latency, removes extra hop dependencies, and lowers overall TCO.
The combined BroadForward SCP/BSF can also expose the Nbsf SBA API, enabling seamless integration in multi‑vendor 5G network deployments.

Features a 100% graphical interface (CLI is also supported) for configuring binding lookup rules, dynamic session correlation criteria, and mediation logic without custom coding or expensive vendor CRs.

Includes native 4G Diameter Rx proxy/relay interworking to connect legacy 4G PCRF nodes and application servers (like IMS P-CSCF) directly to 5G PCFs, ensuring policy state continuity across 4G and 5G networks.

Trusted by professionals

See why leading professionals choose BroadForward.

We’re proud to have been leveraging the BroadForward platform for quite a while. The solution has played an important role in enabling connectivity with operators and providers preparing for the 5G SA era. Its flexibility, reliability, and future-ready architecture make it a standout platform in the industry.

An elegant and innovative solution to a legacy problem of critical voice networks — fulfils an immediate market need

This not only saves money, but critically speeds time to market

An elegant and innovative solution to a legacy problem of critical voice networks — fulfils an immediate market need

This not only saves money, but critically speeds time to market

One of the few independent signaling experts successful in winning business from operators looking for a multi-technology signaling platform

BroadForward’s solutions have already strengthened our signaling capabilities, driving greater operational efficiency

One of the few independent signaling experts successful in winning business from operators looking for a multi-technology signaling platform

Specifications

Everything you need to evaluate, in one place

Supported Standards & Core Features

3GPP BSF Specifications Fully compliant with 3GPP TS 29.500, 29.501, 23.501, 23.502 and 29.521 for Nbsf service based management and discovery.
3GPP Nbsf Service Support Implements Nbsf_Management (register, update, deregister) and Nbsf_Management_Discovery for AF/NEF access.
Multi-Identifier Session Binding Stores and resolves bindings using combinations of subscriber identifiers: IPv4, IPv6 prefix, SUPI, GPSI, DNN, S NSSAI, and UE IP assignments.
Flexible NF Selection Selects the correct PCF instance using any available identifier and maintains the resulting binding for consistent policy enforcement.
High-Performance Distributed Database Built in, in memory session database delivering microsecond binding storage and real time query resolution at scale.
Binding Information Management Creates, updates, and manages binding records and routes requests to the correct PCF instance based on stored attributes.

Extended Features

Converged Engine & Native SCP Co Hosting Runs on the BFX USC platform, enabling BSF and SCP to operate on the same software instance. Eliminates extra hops, reduces latency, and lowers TCO while using the same GUI and workflows.
Script-Free GUI Signaling Orchestration 100% graphical environment (CLI supported) for defining binding policies, correlation logic, parameter translation, and lookup rules — no scripting or vendor CRs required.
Diameter Rx ↔ HTTP/2 Interworking Provides native Diameter Rx proxy/relay functionality to route legacy AF requests (e.g., IMS P CSCF) to the correct 5G PCF.
Multi-Slice & Multi-Access Binding (optional) Supports slice aware PCF selection and maintains independent bindings for 3GPP and non 3GPP (Wi Fi/N3IWF) access sessions.
NF Management & NF Discovery Services Supports NF Management and NF Discovery, including storage and retrieval of binding information in the internal database.

Get more product information

Request the latest data sheet for the BroadForward BSF and share it with your team for a complete technical overview.

Full technical specifications and feature list
Deployment architecture and SCP co-hosting integration overview

FAQ

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Deployment

Freedom of Environment: Deploying Where it Makes Sense

With the BFX Unified Signaling Core (USC) at its foundation, operators are not tied to a specific hardware vendor, appliance cycle, or hyperscaler. Regardless of where the BroadForward BSF is deployed, it can be redeployed using the same configuration on virtual machines, containers, or bare metal. Because BroadForward BSF separates the underlying execution platform from its binding logic, session state storage, and interworking profiles, moving environments requires no re-engineering. All policy binding rules, Diameter Rx mapping tables, and 3GPP Nbsf profiles built in the GUI can be exported as clean, platform-independent configuration files.