Network Bridge Overview

About Network Bridge

Network Bridge is a transformation application for 5G-enabled communication services. It allows two network applications with different protocols and formats to communicate with each other. For example, it enables an online charging system (OCS) from one vendor to interface with an OCS from another vendor.

Network Bridge receives REST API messages from a source network application, converts the messages into the appropriate format, and then sends the messages to a destination network application. Likewise, Network Bridge performs the reverse when the destination needs to send messages back to the source. To view the supported REST API message types, see "About the Supported Nchf Service Operations" and "About the Supported Npcf Service Operations".

Network Bridge can perform the following types of conversion:

Protocol transformation: Converts REST API messages between the HTTP and Diameter protocols, allowing communication between 5G network applications and 4G LTE OCSs or PCRFs. By default, Network Bridge supports protocol transformation between:
- N40 interfaces and Gy interfaces
- N7 interfaces and Gx interfaces
Event translation: Modifies data included in REST API messages and their payloads to meet the needs of downstream network applications. For example, it can add, modify, and delete fields from message payloads.

Network Bridge converts incoming and outgoing messages using the rules you specify. The rules define a message's criteria to qualify for conversion and how to convert the message. For protocol transformation, the Network Bridge package includes protocol rule files for N40-to-Gy conversion and N7-to-Gx conversion that are ready for immediate use. You do not need to perform any modifications on these files.

To configure Network Bridge for event translation, such as from one 5G network application to another, you must manually create a rule file that specifies the criteria and the fields and values to change. See "About the Mutation Rule File".

About the Supported Nchf Service Operations

Table 1-1 shows the types of Nchf operations that Network Bridge supports. To create, update, or end a converged charging session, the NF submits an HTTP POST request to the URI shown in the table.

Table 1-1 Supported CHF Service Operation Types

Nchf Operation	Request Originator	URI	Description
Nchf_ConvergedCharging_Create	NF	apiRoot/nchf-convergedcharging/v3/chargingdata	Creates an initial quota reservation for a converged charging session. For example, initially reserving 500 MB for a data session.
Nchf_ConvergedCharging_Update	NF	apiRoot/nchf-convergedcharging/v3/chargingdata/ChargingDataRef/update	Updates the quota reservation and reports the current service usage. For example, reserving an additional 100 MB and reporting that the customer has used 499 MB from the initial quota reservation.
Nchf_ConvergedCharging_Delete	NF	apiRoot/nchf-convergedcharging/v3/chargingdata/ChargingDataRef/release	Ends a converged charging session by releasing the subscriber's reservation and then providing a last report of service usage.
Nchf_ConvergedCharging_UpdateNotify	CHF	notificationUri/update notificationUri/terminate	Notifies the NF that one of the following is required: Reauthorization of the session Ending the session

where:

apiRoot is the URL for accessing the Network Bridge server, which is either http://hostname:httpPort or https://hostname:httpsPort.
chargingDataRef is the unique identifier for a charging data resource in a Public Land Mobile Network (PLMN).
notificationURI is the recipient of notifications sent by the CHF, such as http://test-notification-url.

For more information about the Nchf service operations, see ETSI TS 132 290 V15.1.0 Technical Specification.

About the Supported Npcf Service Operations

Table 1-2 shows the types of Npcf operations that Network Bridge supports. To create, update, or end a policy-controlled session, the NF submits an HTTP POST request to the URI shown in the table.

Table 1-2 Supported PCRF Service Operation Types

Npcf Operation	Request Originator	URI	Description
Npcf_SMPolicyControl_Create	NF	apiRoot/npcf-smpolicycontrol/v1/sm-policies	Creates a PDU session with a specified QoS flow.
Npcf_SMPolicyControl_Update	NF	apiRoot/npcf-smpolicycontrol/v1/sm-policies/smPolicyId/update	Updates the PDU session when a policy control request trigger condition is met. For example, changing the QoS flow when a user's location changes.
Npcf_SMPolicyControl_Delete	NF	apiRoot/npcf-smpolicycontrol/v1/sm-policies/smPolicyId/delete	Deletes the SM Policy Association and the associated resources.
Npcf_SMPolicyControl_UpdateNotify	PCF	notificationUri/update notificationUri/terminate	Updates or deletes the PDU session-related policy context at the SMF and the policy control request trigger information.

where:

apiRoot is the URL for accessing the Network Bridge server, which is either http://hostname:httpPort or https://hostname:httpsPort.
smPolicyId is the unique identifier for an individual SM Policy resource.
notificationURI is the recipient of notifications sent by the CHF, such as http://test-notification-url.

For more information about the Pcrf service operations, see ETSI TS 129 512 V15.0.0 Technical Specification.