Binding Support Function (BSF)

The BroadForward Binding Support Function (BroadForward BSF) enables policy/charging (PCF/CHF) scaling of the 5G network while ensuring session correlation for HTTP/2. For converged networks, the BroadForward BSF can also maintain session state between HTTP/2 and Diameter. The core function of the BSF is to track sessions that are located anywhere in the network, but share common criteria, such as subscriber identifiers.

5G Binding Support: enables scaling the policy/charging network

The 5G Binding Support Function (BSF) is comparable with the Session Binding Function on the Diameter Routing Agent (DRA) used in 4G. It becomes a mandatory requirement when multiple Policy Control Function (PCF) systems are deployed in the network. Because the BSF enables correlation of sessions across multiple policy servers, it provides operators with the ability to scale the network.

The Binding Support Function is specified in 3GPP TS 23.502, 3GPP TS 23.503 and TS 29.513 for key functions such as:

  • Finding the binding information (e.g. the address information of the selected PCF)
  • Allowing systems (e.g. PCF) to register, update and remove the binding information
  • Allowing systems (e.g. AF, NEF) to discover the binding information (e.g. the address information of the selected PCF)

BroadForward BSF
The BroadForward BSF supports the relevant standards and offers unique flexibility through an extensive, integrated set of routing, interworking and database capabilities, including HTTP/2 and Diameter interworking scenarios:

  • Supports the ability to create various binding records and route to the appropriate PCF based on the binding information
  • Support for NF Management and NF Discovery services including storage of the bindings in on-board DB
  • Support for NF selection using any available identifiers like SUPI, S-NSSAI, GPSI, DNN and store the corresponding binding
  • Supports 4G Diameter Rx interface towards any legacy AF for backward compatibility
  • Acts as proxy/relay for Diameter Rx messages; supporting binding lookup on the receipt of Rx messages (e.g. from a P-CSCF).
  • Can be deployed standalone or co-located with other (4G/5G) network functions, such as:

Combining network functions
The BroadForward BSF runs on a unique single-engine software design, allowing operators to combine multiple functions on the same platform. This provides many benefits, such as:

  • Reduction of integration points, and on-board capability for interworking and interoperability
  • Centralized and uniform IT integration, signaling management, configuration, provisioning, subscriber management, reporting and control
  • Centralized and uniform use of common network applications (e.g. firewall, number portability, steering of roaming, routing (DRA/STP/SCP)
  • Easy to operate, uniform operations, reporting and management across domains
  • Single capacity license with free traffic mix across supported protocols
  • BroadForward 5G functions

Virtualized, cloud-based and containerized deployment
The BroadForward BSF provides unmatched flexibility with various deployment options, including bare metal, virtual machines, containers, and cloud environments, all while maintaining a low resource footprint. This 100% software-based, hardware-agnostic solution eliminates the need for specialized hardware or proprietary operating systems. Deploying the BroadForward BSF on a common platform facilitates the transition for operators and vendors from proprietary appliance systems to a standardized, hardware-agnostic, software-only infrastructure.

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