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S3 Interface, dsTest, Developing Solutions, MMe, 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 S3. S3 is a GTP signaling-only interface, used between the Serving GPRS Support Node (SGSN) and the Mobility Management Entities (MME) to support inter-system mobility. With the dsTest S3 Interface application, you can test GTP-C initiators (SGSNs), and verify responses from responders (MMEs).

The S3 interface is between MMEs and SGSNs enhanced to support EPS mobility in order to support handover to/from 2G/3G radio access network for 3GPP accesses. The functions supported include transfer of information relating to the terminal that is being handed over and handover/relocation messages.

The S3 Interface Application, along with other dsTest 4G interface applications provide 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 S3 Interface Application initiates the following Mobility Management events from a Simulated SGSN node:

  • Identification Request/Response
  • Context Request/Response
  • Forward Relocation Request/Response
  • Forward Relocation Complete Notification/Acknowledge
  • Relocation Cancel Request/Response
  • Detach Notification

A complete set of events that can be generated with the S3 interface application can be found here, and our GTPv2 Dictionary can be used to help construct, test, and interpret the results of your S3 testing.

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 GUI application that runs on your PC.

MME Testing (GTP-C Initiator Simulation – SGSN)

Verify the reaction of your MMEs to UE mobility by simulating a SGSN.  Verify you’re your MME responds, or acknowledgments, correctly to:

  • Identity requests when a UE has moved to a different SGSN;
  • Bearer context information requests for the UE as a part of TAU/RAU procedure and UTRAN/GERAN to E-UTRAN/UTRAN (HSPA) SRVCC procedure;
  • Relocation requests as part of Inter-RAT handover and other relocation procedures;
  • Forward Relocation Complete Notification messages, indicating a handover has been successfully finished;
  • Relocation cancel requests as part of the Inter RAT handover cancel procedure;
  • Detach notifications as a part of detach procedure if the Idle mode Signaling Reduction (ISR) is activated between the MME and SGSN for the UE.

Your S3 SmartEvents state machine provides the ability to create S3 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.

Test your MME performance by initiating context requests, detach notifications, and relocation requests from a simulated SGSN in volume.

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

SGSN Testing (GTP-C Responder Simulation – MME)

Simulate GTPv2-C interfaces to your SGSN GTP-C initiator. Verify that the initiator correctly interprets the S3 responses. Test the capacity and performance of your SGSN with other dsTest interface applications to trigger network-initiated events and validate the resulting signaling and user plane traffic.

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 S3 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 S3 measurements and socket measurements.

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

Supporting StandardsS3 Interface, S3 Testing, GTP Testing, MME Testing, SGSN Testing, dsTest, Developing Solutions