In this section:
Overview
The DSC Platform User Application Protocol (UAP) provides access to this system’s SS7 message information stream through a TCP/IP interface. The UAP can terminate the SS7 message stream at the MTP3 or at the SCCP, allowing you to access both call control (ISUP) and service-oriented (SCCP/TCAP) messages. The UAP also provides an Integrated Monitoring Feed (IMF) for traffic analysis.
While the SS7 protocol is complex, the UAP protocol uses a simpler design providing you with the same functionality as the SS7 protocol. In essence, the MTP3 and SCCP UAP interfaces are equivalent to M3UA and SUA, respectively, with the exception that the UAP is proprietary to Ribbon and is used over TCP instead of SCTP.
The UAP allows IP applications to connect and register with the DSC Platform SS7 stack. This connection establishes a communication channel between this stack and the IP application through which messages are sent and received. The IP application can access the SS7 message stream as a user of MTP3 for ISUP messages, or as a user of SCCP for TCAP messages.
Internet Engineering Task Force (IETF) Signaling Transport (SIGTRAN) standard protocols are supported by the DSC Platform. It is recommended that you review these protocols before using the UAP. For information about these protocols, see the appropriate chapter in the SS7 Application Guide 1.
Benefits of Using UAP
Applications Can Run on Any Application Server Platform
The UAP is based on an industry standard TCP/IP interface that can be connected to most computers.
Internationally Proven SS7 Support
The DSC Platform SS7 stack supports many different international versions of the SS7 protocol. These SS7 protocols have been successfully deployed in public networks including International Telecommunication Union (ITU), American National Standards Institute (ANSI), China, and Japan.
Unparalleled Range of SS7 Connection Options
The DSC Platform can be configured as virtually any SS7 network element and can be connected to the public SS7 network in various configurations.
Configured as a Signal Transfer Point (STP), the DSC Platform can support A-Links to end nodes, B-Links, and D-Links to other STPs, and C-Links to its mated STP. Configured as a Signaling End Point (SEP), this system can support A-Links to STPs, or F-Links to other end nodes.
Reliability
The DSC Platform can be configured as an STP and deployed in a mated pair configuration to increase the reliability and survivability of the overall system. If either STP experiences a link or node problem, the affected message traffic is automatically re-routed through the mate STP without losing any information. When the first STP has been restored to its operational condition, the traffic is automatically returned to its normal routing, again without losing any information.
Scalability
The DSC Platform supports multiple virtual point codes (VPCs). Each of these point codes can be used to uniquely identify an IP application that is accessed through the UAP. In this way, a single DSC Platform can act as the front end for many distinct IP applications, all of which are separately addressable from the public SS7 network.
Functional Description
The UAP gives IP applications the ability to communicate with the Ribbon SS7 stack (see Figure DSC Platform and IP Applications). This stack, in turn, communicates with the public SS7 network. The connection between the IP application and the SS7 stack is created using TCP/IP that is supported on most computers.
The Ribbon SS7 stack is a complete protocol stack up to and including the SCCP. Each application that has to communicate with the SS7 network through the SS7 stack undertakes a registration process using the UAP. This registration process identifies the IP application and establishes the parameters for the communication, including the point code (PC).
Applications that require Integrated Services Digital Network User Part (ISUP) messages can register with the MTP3, while applications that require SCCP/Transaction Capabilities Application Part (TCAP) messages can register with the SCCP. At the conclusion of the registration process, the DSC Platform has the information required to send and receive the appropriate SS7 messages on each socket. Applications can register with both MTP3 and SCCP, and multiple applications can register through the same socket (see Figure DSC Platform Architecture).
The SS7 network is, by design, a guaranteed bandwidth and highly redundant network. Response times are strictly enforced to ensure reliable quality of service. The TCP/IP network, in contrast, was originally designed to support multiple users over relatively slow networks. The UAP and the DSC Platform manage the interface between these two fundamentally different networks by doing the following:
- disabling the Nagle algorithm that delays TCP/IP transmission
- configuring TCP/IP for a non-blocking interface
- implementing a heartbeat message to detect network failures
- creating a message header to delimit message boundaries
For more information about configuring these features, see Configuring the TCP/IP Interface.
When an IP application has properly initialized and configured the TCP/IP interface and has sent the appropriate messages to register with the DSC Platform SS7 stack, the IP application and the SS7 stack begins to exchange traffic messages over TCP/IP.
MTP3/SCCP IP Application Management Operation Sequence
Setup
The system setup comprises the stages described in this section.
Connect to the DSC Platform
The application connects to a socket on the Ribbon SS7 stack using BSD socket library calls.
Receive Local Status
The Ribbon SS7 stack sends the local status of the SS7 network.
Register with the DSC Platform
The application sends a registration request to the DSC Platform, specifying a point code (PC) and a subsystem number (SSN) for the Signaling Connection Control Part (SCCP) user interface, and a PC and a service indicator (SI) for the MTP3 user interface.
Receive Registration Acknowledgment
The DSC Platform returns a message indicating the status of the register request.
Operation
The system operation comprises the stages described in this section.
Send and Receive Messages
The application sends MTP3 or SCCP messages to and from the SS7 network. Standard BSD library functions provide a non-blocking interface to the TCP/IP LAN that is servicing the application platform and the DSC Platform.
Shutdown
The system shutdown comprises the stages described in this section.
Deregister from the DSC Platform
At any given time, the application may deregister itself from the DSC Platform. A sudden closure of the TCP/IP socket would have the same effect.
Receive Deregistration Acknowledgement
The DSC Platform returns a message indicating the status of the deregister request.
Close the Connection to the DSC Platform
The application properly closes the connection to the DSC Platform that is necessary to ensure maximum performance.