dsTest supports the Ud/Sp interface between user data repositories, such as the Home Subscriber Server (HSS) and the Policy and Charging Rules Function (PCRF), as specified in 3GPP TS 23.335 and TS 29.335.
Sp is the reference point between the (client) PCRF and the (server) Subscription Profile Repository (SPR), enabling the PCRF to obtain subscription information required for policy and charging rules installation and removal.
The Ud reference point provides the same functionality as the Sp reference point with respect to unified (or user) data repositories (UDR) such as the HSS. This interface allows a server, acting as an Application Front End (FE) to request subscription information from the UDR, and allows the UDR to notify the server when the subscription information has changed.
Standardization of the Data Model for the Ud/Sp interface between Front-Ends and the UDR is not specified by 3GPP. The structure of the user data is operator dependent, so a complete specification of the Ud/Sp Interface is not possible. However, general requirements for the Ud/Sp interface under the Unified (or User) Data Convergence (UDC) concept are specified in TS 23.335:
- This reference point shall allow the different FEs to create, read, modify and delete user data stored in the UDR using the harmonized access interface;
- This reference point shall support subscriptions/notifications functionality which allows a FE to be notified about specific events which may occur on specific user data in the UDR;
- Through the reference point, an FE shall only interface with the UDR for the data relevant to its function, and not be impacted by other data that UDR stores for other applications;
- The user data that an FE accesses in the UDR shall comply with an agreed data structure between the FE and the UDR.
- The data structures shall comply with the Application Specific Data Model (specified in 3GPP TS 32.182 and in 3GPP TS 32.181);
- Operations and transactions over Ud shall support the ACID (Atomicity, Consistency, Isolation, and Durability) characteristics.
The UDR data model uses the Lightweight Directory Access Protocol (LDAP) to access the user data, and SOAP for the Subscribe and Notification messages.
With the 5G Next Generation core (5GC), the current assumption is that the UDR will be extended to provide the Unified Data Repository functionality and support the service based Nudr interface defined in the 5GC specifications TS 23.501 and TS 23.502.
dsTest supports these requirements for the Ud/Sp Interfaces with the following implementation:
- Open Link – BindRequest
- Close Link – UnbindRequest
- Query Request/Response – SearchRequest/ SearchResultEntry, SearchResultReference, SearchResultDone
- Add Request/Response – AddRequest/AddResponse or ModifyResponse
- Delete Request/Response – DelRequest or ModifyRequest/DelResponse or ModifyResponse
- Update Request/Response – ModifyRequest/ModifyResponse
- Compare Request/Response – CompareRequest/CompareResponse
- Abandon – AbandonRequest
A full set of events available for the Ud/Sp interfaces can be found here.