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Nu Nodes

dsTest supports the 3GPP Representational State Transfer (RESTful) Nu Interface between the Services Capability Exposure Function (SCEF) and the Packet Flow Description Function (PFDF).   3GPP specifies this interface with HTTP protocol bindings using a REST architecture for the various individual interface definitions, including naming conventions, content type negotiation, representation formats and serialization, and fault definitions.

An SCEF supports the management of Packet Flow Descriptions (PFDs) provided by a Service Capability Server/Application Server (SCS/AS). The Nu Interface is used by the SCEF to provision PFDs to the PFDF that have been received from the SCS/AS, and for reporting the result of the PFD provisioning from the PFDF to the SCEF. To perform this functionality, the SCEF acts as an HTTP client and initiates a TCP connection with the PFDF, which acts as an HTTP server.

The implementation of the Nu Interface provides additional features to support CIoT Network Testing with dsTest, with our other CIoT/NB-IoT interface applications.


The SCEF uses methods to indicate to the PFDF what action has to be performed, with every HTTP request message containing a method. The SCEF uses the HTTP POST method to provision PFDs for a set of application identifiers. The request URI defines the address responsible for the management of the PFDs provisioning as a controller resource. Every HTTP request results in a response message that contains a status code and further information in its body, if required. The SCEF waits for a response before initiating a further request.

A complete set of events that can be generated by the dsTest SCEF emulator over the Nu interface can be found here.

Advanced Testing Features

SmartEvents — Alter application behavior or coordinate multiple interface applications with SmartEvents. Our programmable, subscriber-level state machine gives you the ability to define handlers for specified application events that can then cause an event in another application to be executed. You can also configure handlers to modify subscriber information during run-time, introduce timers, or randomize subscriber behavior based on configurable probabilities to name 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 solution. 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.

Operational Measurements

dsTest provides rich sets of measurements for the Nu interface:

  • 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 Nu measurements and socket measurements.

You can read more about the reporting features offered with dsTest and dsClient here.

Supporting StandardsNu Protocol Stack