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S4 Interface, dsTest, Developing Solutions, SGW, SGSN, GTP, LTE Testing, EPC Testing

dsTest supports the GPRS Tunneling Protocol Version 2 for Control plane (GTPv2-C) message sets over the Evolved Packet Core (EPC) signaling interface S4. With the dsTest S4 Interface application, you can test GTP-C initiators Serving GPRS Support Nodes (SGSNs), and verify responses from responder serving gateways (SGWs).

The S4 Interface Application, along with other dsTest 4G interface applications, provides dsTest users with complete EPC testing capability.  Our eNodeB, MME, SGW, PGW, and Home Subscriber Server (HSS) emulators support end-to-end testing of IP connectivity to LTE access.


The S4 Interface Application initiates the following events from a Release 8 simulated SGSN node:

  • Create/Delete Session
  • Create/Delete  default bearer
  • Add a rule to create or modify/update  a dedicated bearer
  • Delete Dedicated Bearer

A complete set of events that can be generated with the S4 interface application can be found here, and our GTPv2 Dictionary  and GTP Cause Value Reference can assist in designing, configuring,  and interpreting GTPv2 test scenarios.

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 GUI, you can create, run, and archive tests, capture, graph and archive operational measurements, capture real-time data flows, and manage your dsTest servers and testing scenarios with a standalone application that runs on your PC.

SGW Testing/GTP-C Initiator Simulation (SGSN)

Verify the reaction of your gateway nodes by simulating a Release 8 SGSN. Your S4 SmartEvents state machine provides the ability to create S4 GTPv2-C message flows and use them in combination with Policy and Charging Control (PCC) interface applications to test gateway elements in the mobile packet core. Use the S4 Interface Application and our SmartEvents feature with other interface applications to trigger network-initiated events from our Emulators and validate the resulting GTP-C signaling.

Test your SGW performance by initiating default bearer activation from the simulated SGSN. Verify that your SGW sends the appropriate response and retains the bearer information.

Read more about our testing solutions.
Read more about our other GTP Interface Applications.

SGSN/MME Testing/GTP-C Responder Simulation (SGW)

Simulate GTPv2-C interfaces to your MME or SGSN GTP-C initiator. Verify that the initiator correctly interprets the gateway GTP-C responses. For example, simulate bearer activation by initiating an Attach and verify that your SGSN sends a Create Session Request, and correctly processes the Create Session Response from the simulated SGW. Verify that your SGSN retains bearer information and attributes, and, upon location changes, sends a Modify Bearer Request and correctly processes a Modify Bearer Response from the simulated SGW.

Test the capacity and performance of your MME with other interface applications to trigger network-initiated events and validate the resulting GTP-C signaling.

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 currently. 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 S4 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 S4 measurements and socket measurements.

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

 Supporting StandardsS4 Stack