2 Using Network Bridge for 5G-to-4G Payload Conversion

You can use Oracle Communications Network Bridge to convert HTTP message payloads from 5G networks into the Diameter protocol, so they can be processed by 4G LTE online charging systems (OCSs) as well as policy and charging rules functions (PCRFs).

Topics in this document:

• About 5G-to-4G Payload Conversion

• 5G-to-4G Network Bridge Architecture

About 5G-to-4G Payload Conversion

Network Bridge can convert REST API messages from 5G network applications into a format for 4G network applications. This functionality prevents your company from needing to switch to a complete 5G core architecture all at once. You can launch a 5G services architecture while using an existing 4G LTE online charging system (OCS) and a 4G policy and charging rules function (PCRF). That is, you can continue using a 4G LTE OCS, such as Oracle Communication Network Charging and Control, to rate 5G service usage from your customers.

When configured for 5G-to-4G payload conversion, the Network Bridge architecture does the following:

• Processes incoming HTTP messages

• Prepares messages for processing by a 4G protocol conversion service

• Converts message payloads between the HTTP protocol and the Diameter protocol

The Network Bridge package includes built-in support for the following:

• Interworking between 5GC SMF and EPC OCS – N40 to Gy

• Interworking between 5GC SMF and EPC PCRF – N7 to Gx

5G-to-4G Network Bridge Architecture

Figure 2-1 shows the Network Bridge architecture for performing 5G-to-4G payload conversion.

Figure 2-1 5G-to-4G Network Bridge Architecture

Description of "Figure 2-1 5G-to-4G Network Bridge Architecture"

For information about configuring Network Bridge for 5G-to-4G payload conversion, see "Configuring Network Bridge for 5G to 4G Payload Transformation" in Network Bridge Cloud Native Installation and Administration Guide.

Processing Messages from 5G NFs to 4G NEs

Network Bridge processes messages from 5G NFs to 4G NEs as follows:

1. The 5G NF sends a credit-control request (CCR) message to the external ingress controller.

2. The external ingress controller directs the incoming message to the Network Bridge Mediation component.

   Note:

   You must configure the ingress controller to route N40 and N7 requests to the Mediation component. See "Installing an Ingress Controller" in Network Bridge Cloud Native Installation and Administration Guide.

3. The Mediation component prepares the message for protocol transformation and optionally adds custom metadata before sending the message to the HTTP to Diameter Adapter component.

4. The HTTP to Diameter Adapter component:

   • Converts the message payload from the HTTP protocol to the Diameter protocol according to rules in the Network Bridge protocol rule file.

   • Sends the message to the Diameter Proxy component.

5. The Diameter Proxy component adds AVPs, such as origin and destination, and then sends the message to the 4G NE.

6. The 4G LTE OCS or PCRF starts, updates, closes, or rates the converged charging session or policy-controlled charging session.

7. The 4G LTE OCS or PCRF responds to the CCR by sending a credit-control answer (CCA) message to the Diameter Proxy component.

8. The Diameter Proxy component stores information about the session in the MySQL NDB and then sends the message to the HTTP to Diameter Adapter component.

9. The HTTP to Diameter Adapter component:

   • Converts the message payload from the Diameter protocol to the HTTP protocol according to rules in the Network Bridge protocol rule file.

   • Sends the message to the Mediation component.

10. The Mediation component sends the message to the external ingress component, which in turn forwards it to the 5G NF.

Processing Messages from 4G NEs to 5G NFs

Network Bridge processes messages from 4G NEs to 5G NFs as follows:

1. The 4G LTE OCS or PCRF sends an RAR message to the Diameter Proxy component.

2. The Diameter Proxy component retrieves session information from the MySQL NDB before sending the message to the Diameter to HTTP Adapter component.

3. The Diameter to HTTP Adapter component:

   • Converts the message payload from the Diameter protocol to the HTTP protocol according to the rules in the Network Bridge protocol rule file.

   • Sends the message to the Egress component.

4. The Egress component optionally adds AVPs, such as Explicit-Route-Record, to the message before sending it to the external egress controller.

5. The external egress controller forwards the message to the 5G NF.

6. The 5G NF responds by sending a reauthorization answer (RAA) message to the external egress controller.

7. The external egress controller forwards the message to the Network Bridge Egress component.

8. The Egress component forwards the message to the Diameter to HTTP Adapter component.

9. The Diameter to HTTP Adapter component:

   • Converts the message payload from the HTTP protocol to the Diameter protocol according to the rules in the Network Bridge protocol rule file.

   • Sends the message to the Diameter Proxy component.

10. The Diameter Proxy component forwards the message to the 4G NE.