Advanced Routing and Screening

Overview

The DSC's MTP3 and GTT routing and screening optional features offer service providers powerful capabilities to inspect and apply treatment of SS7 messages transiting their network. The ability of the DSC to establish multilevel screening criteria and flexible routing provides significant benefits in areas of network security, network troubleshooting, billing verification, and traffic steering. The features listed and described on this page give a service provider the ultimate flexibility to control the flow of signaling traffic through their network to meet their requirements.

For troubleshooting, call flows through a service provider's network, Message Signal Unit (MSU) Tracing provides a valuable utility to diagnose and investigate messages transiting through the STP. Using filters, MSU Tracing logs and counts messages passing through the system.

Global Title Translation

For non-ISUP signaling traffic, enabling Global Title Translation (GTT) on the STP frees originating signaling points from the burden of having to know every potential destination to which they might have to route a message. A switch can originate an SS7 Signaling Connection Control Part (SCCP) query and address it to an STP along with a request to perform GTT. The receiving STP makes a determination of the intended address (DPC) based on the digits and other Called Party Address (PA) parameters of the SCCP message.

Advanced GTT routing provides the ability to route an SCCP message by using the Called and Calling Party Address parameters and the MTP3 Routing Label's OPC. For more information, refer to Advanced GTT Routing.

For information about configuring GTT, refer to Configuring the Global Title Translation.

Gateway Screening

Gateway Screening (GWS) is essential to a service provider's network to ensure security and integrity between interconnected networks. GWS criteria can be defined for each linkset, allowing individual rules to be specified for each interconnected network. GWS prevents unauthorized use of an STP and controls the flow of the SS7 messages into and through the STP.

For information about configuring GWS, refer to Configuring the Gateway Screening and MSU Tracing.

Advanced Screening and Routing

While standard Gateway Screening provides the means for allowing or disallowing messages to enter a service provider's network, Advanced Message Screening - Redirect, Advanced Message Screening - SCCP and TCAP, Advanced GTT Routing, and Advanced MTP Routing are used to steer specific traffic over an alternate route, providing a service provider with a very powerful mechanism to control traffic flow through their network

For information about configuring these functions, refer to the appropriate chapters in the SS7 Application Guide 2.

To illustrate the benefits of this flexible routing, consider the following examples.

Advanced Message Screening - Redirect

By using the Transaction Capabilities Application Part (TCAP) operation code to identify Short Message Service (SMS) traffic, a service provider can separate SMS messages from the SS7 Integrated Services Digital Network (ISDN) User Part (ISUP) traffic and steer SMS traffic over a different set of links. This functionality enables the service provider to steer the SMS traffic over IP-based signaling links and ISUP traffic over circuit-switched signaling links, offloading an operator's existing facilities.

Similarly, using a combination of the originating PC (OPC) and a destination PC (DPC) different routes can be selected on business agreements with different inter-connectivity partners.

Mobile and multimedia applications continue to drive revenue growth for service providers. To bring these new service offerings to their subscriber base and increase their revenue per subscriber, many of these applications require a feed from the SS7 network. Using Advanced Message Screening - Redirect, it is possible to redirect or copy SS7 messages to any registered application by PC or by a string representing that application connection.

For more information, refer to GWST Tables.

Advanced Message Screening - SCCP and TCAP

Advanced Message Screening - SCCP and TCAP provide enhanced screening capabilities for messages using SCCP Called and Calling Digits and TCAP Operation Code. These functionalities are not defined in the Signaling Transfer Point (STP) Generic Requirements GR-82, Issue 15, December 2011 specifications and do not require a license.

The SCCP Called and Calling Digits screening expands on the SCCP parameters beyond the standard Called and Calling PA to include the party address digits. The SCCP record defines a destination called or an originating calling switch via its digits in the network that passes the initial gateway screening. This functionality makes it easier for service providers to discard, to passthrough, or (if licensed) to redirect traffic using SCCP screening based on the dialed digits.

The TCAP can be used as the next screening step after SIO and SCCP screening tables for SCCP traffic. The TCAP screening, based on the operation code, is a useful feature for service providers to enable traffic screening for Global System for Mobile Communication (GSM) or Code Division Multiple Access (CDMA) applications.

For more information, refer to GWST Tables.

Advanced GTT Routing

Service providers, many of whom engage in multiple inter-carrier business agreements, are requesting more control over how messages are routed. The Advanced GTT Routing option expands on the searchable parameters beyond the standard Called Party Address (PA) to include additional Global Title Parameters such as SCCP Calling PA and OPC contained within the MTP routing label.

With the ability to search on these parameters alone or in a combination, an operator who is handling roaming traffic through their STP can identify a roaming subscriber's service provider from the SCCP Calling PA and OPC and steer this roaming subscriber's traffic to traverse the lowest cost SS7 network to reach the final destination.

Service providers can similarly use these parameters to block traffic between providers where agreements may not exist.

For more information, refer to Global Title Translation.

Advanced Managed Routing

In networks where a service provider is looking to deploy centralized link monitoring, in a distributed SS7 Core/Edge network topology, the Advanced Managed Routing provides the flexibility to route all traffic to the core STP when a Ribbon node is deployed at the edge of the network (IP-Edge).

For more information, refer to Advanced Managed Routing.