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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 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.  A comprehensive set of Operational Measurement for the S4 Interface Application is available via dsClient CLI or dsClient GUI.


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.

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 network testing.
Read more about our Emulators.
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

Using our SmartEvents application, you have the ability to create simple to complex transaction flow state machines for the S4 interface.  You can construct different paths for success, failure, or other conditions, all well defined within the state machine.  Using our SmartAVP feature, you can create and customize the incoming and outgoing S4 messages increase the flexibility of your test scenarios.  Multiple handlers can be used with different templates of the same message type in order to execute various actions or state changes depending on the composition of a received message.

Read more about GTP functional and compliance testing with dsTest.

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.

 Supporting StandardsS4 Stack

General Reference Guides

Read more about dsTest.