GWST Overview

Gateway Screening and MSU Tracing (GWST) is a feature of the Signaling Transfer Point (STP) that allows network administrators to trace and control the flow of SS7 messages into and through a signaling network.

This feature includes the following functionalities:

Gateway Screening

The gateway screening functionality (GWS) is a licensed feature that determines if incoming messages from an SS7 linkset or from a user must be discarded based on the configured criteria. If a message is accepted, this message continues its STP processing for final routing. The STP GWS functionality for SS7 linkset traffic is defined in the SS7 ANSI GR-82, Issue 10, December 2006 specifications and is applied to both ANSI and ITU networks.

The GWST provisioning must allow sequential screening steps for SS7 messages on any given SS7 linkset or Incoming AppID. Each linkset and Incoming AppID may define its own screening steps for multiple networks management options. Measurements and statistics are kept for rejections and screening validations to monitor the GWS. For more information about gateway screening provisioning, refer to GWST Provisioning.

Enhanced Screening

The GWST has an enhanced screening functionality for TCAP and SCCP Called and Calling Digits that are not defined in the SS7 specifications. This allows TCAP screening on the operation code and other TCAP fields and SCCP screening on the party address digits, respectively.

MSU Tracing

The MSU tracing functionality uses the screening tables to determine if an incoming message must be traced through the DSC - SP2000 Platform STP process. Similarly to Gateway Screening, MSU tracing allows you to perform screening validation, but the screening results are not applied. This feature is unlicensed and is available to assist in traffic analysis.

Traffic Redirection

The GWST also manages the traffic redirection functionality as a licensed feature to allow traffic that meets a given criteria based on screening tables to be rerouted to either a local application based on an Application ID, or another remote PC than the DPC contained in the MSU.

Gateway Accounting

The gateway accounting functionality (GWA) is a licensed feature to allow network administrators to support cascade remuneration of the SS7 messages coming into or through a signaling network from an SS7 linkset or from a user.

The accounting method used is based on the ITU Recommendation Q.752, 1997/06 and is applied to both ANSI and ITU networks. It is the responsibility of the user of this feature to properly define the necessary accounting rules based on the Accounting Criteria for MTP3 and/or SCCP for any remunerations.

The GWST accounting has an enhanced TCAP and SCCP support functionality not defined in the SS7 specifications to allow for peg counts on TCAP operation codes and SCCP Calling digits prefix.

Process Event

The Process Event feature that appears in the UI, but is not described in this guide, provides an alarm type which ensures that the applications in all slots function as expected. With this feature, each application defines its own concept of functioning as expected, which means that the configuration/database files are synchronized and loaded, inter-peer connections are correctly established, and the peer applications are ready to process traffic.

If the application and its processes do not function as expected, an alarm is raised that is visible on the system's alarm panel. For more information about alarms, refer to the appropriate section in the DSC Alarms Guide.

In accordance with GR-82-Core, Signaling Transfer Point (STP) Generic Requirements (A Module of FR-CCS-18), Issue 10, December 2006, the DSC - SP2000 Platform supports Memory Space Accounting (MSA). For more information about how this feature applies to GWST, refer to the appropriate section in the DSC - SP2000 Platform Manager User Guide.