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Nudm Service-Based Interface

UDM Testing with dsTest

The Unified Data Management (UDM) network function provides authentication and subscription information to the 5G Core (5GC) network functions that are generally concerned with controlling network access and establishing a subscriber’s session. It also manages dynamic information regarding the subscriber’s current session and provides that information to service consumers on request. The Nudm Service-Based Interface (SBI) accomplishes all of these functions. A UDM may be stateful — in other words it stores data locally —  or stateless. A stateless UDM manages subscription data in the UDR through the Nudr service.

The dsTest Nudm SBI application supports the services briefly described below, which are specified in TS 29.503.

Nudm_SubscriberDataManagement Service (Nudm_SDM)

The SDM service provides the requested data from an individual subscriber’s subscription to a service consumer. Network functions that consume SDM information can also subscribe to notifications sent by the Nudm producer when that information changes. The subscription information provided by this service includes data needed for network slice selection, UE registration, network access and mobility management, SMF selection, session management, UE SMF context, SMS subscription and management, and PDU session establishment. This service also provides identifier translation, returning the Subscription Permanent Identifier (SUPI) associated with a Generic Public Subscription Identifier (GPSI), for example.

Nudm_UEContextManagement Service (Nudm_UECM)

Information regarding the UE’s current session is managed by the UECM service. The network functions that serve a UE register that information with the UDM, along with status information when appropriate, and deregister after they are no longer serving that UE. A network function may also be notified that it has been deregistered when the UDM has determined that it is no longer the registered service provider for a particular UE. Additionally, this service is used by the AMF to update the UE’s Permanent Equipment Identifier (PEI) and is used by the UDM to notify a registered AMF or SMF that P-CSCF restoration is required. Interested network functions can obtain context information on request to learn, for example, which AMF is currently serving a particular UE.

Nudm_UEAuthentication Service (Nudm_UEAU)

The UDM provides the AUSF with the authentication method and associated authentication vector for the specified UE. In the event that the UE is identified by a Subscriber Concealed Identifier (SUCI) the UDM returns a SUPI. The authenticating network function in turn uses this service to inform the UDM of the authentication result in either case — whether the authentication succeeded or failed.

Nudm_EventExposure Service (Nudm_EE)

NEFs use this service to subscribe to or unsubscribe from UDM event notifications. If the NEF’s request is for events exposed by the AMF then the UDM utilizes the AMF’s event exposure service (Namf_EventExposure) to subscribe or unsubscribe on behalf of the NEF.

A UDM exposes the following events:


Nudm_ParameterProvision Service (Nudm_PP)

An external party can update, when permitted, subscription data through the PP service via an NEF. This data includes information regarding expected UE movement and communication characteristics.


dsTest supports Nudm service delivery across the 5GC reference points shown in the table below. dsTest’s Subscriber Profile Repository (SPR) node emulates a stateful UDM, storing subscription and context data in its subscriber database and providing Nudm services to the consumers in your 5G test network, while also verifying their compliance with service specifications. Conversely, if you are testing a UDM, you can use our service consumer simulators to surround your UDM and test its capacity and performance.

read moreRead more about dsTest capacity and performance.

As with all dsTest products, the node configurations and test scenarios are easily defined and configured with XML files that are validated against a published XML Schema to avoid invalid definitions. With our dsClient Desktop application you can create, run, and archive tests; capture, graph and archive operational measurements; capture real-time data flows and subscriber events; and manage your dsTest platforms and testing scenarios with a standalone application that runs on your PC.

read moreRead more about the dsClient Desktop application.

Advanced Testing Features

SmartEvents — Alter application behavior or coordinate multiple interface applications with SmartEvents — our programmable, subscriber-level state machine. All dsTest applications are event-driven, enabling you to easily alter subscribers’ activities. Use our visual composer to draw your state machine and to trace a single subscriber’s path through the state machine while the test is running. Define event handlers that affect a subscriber’s behavior in an application, or that trigger an event in another application. You can also configure event handlers to modify subscriber information during run-time, introduce timers, or randomize subscriber behavior based on configurable probabilities to name just a few of the many options in one of dsTest’s most powerful features.

SmartMessageElement — Insert, delete, or replace elements in Diameter, RADIUS, MAP, LDAP, GTP, REST, or SOAP messages with our SmartMessageElement feature. Define proprietary signaling or corrupt elements to facilitate negative testing. You can specify when your elements are used with SmartEvents.

Traffic Profile — Draw the shape of your test actions across time with Traffic Profile. You can define the rate for any action as a static rate or reference a Traffic Profile configuration, which also means that multiple Traffic Profiles can be running concurrently. Use Traffic Profile in conjunction with the randomizing features in SmartEvents to design a test that more truly simulates real-world network activity.

REST Dictionary — Add conformance testing to your performance or functional test with our REST Dictionary. You can validate message types and JSON structures by simply including our base dictionary. You can also build custom dictionaries to explicitly define required parameter and property values and selectively include the dictionary to be used for a particular test.

Operational Measurements

dsTest provides rich sets of measurements for Nudm services:

  • Transaction and transport layer attempts, successes, and failures
  • Transaction duration, transactions-per-second, and round-trip delay
  • Message and byte counters
  • Errors encountered and error indications received in messages

See our Online Help for SDM Service measurements, UECM Service measurements, and socket measurements.

read moreRead more about the reporting features offered with dsTest and dsClient.

Reference Standards