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Chapter 1
Introduction
- 1.1 SS7 Architecture
- 1.2 TCAP Layer Services
- The SS7 Transaction Capabilities Application Part (TCAP) developer's kit provides the tools for developing applications which can utilize the transaction capabilities of the SS7 network. The TCAP developer's kit includes the TCAP protocol layer which executes on TX Series processors, APIs for both transaction-based applications as well as for configuring and managing the TCAP layer, and example applications and management tools.
- The TX Series TCAP implementation supports development of applications which are compliant with either the ANSI 1992 (T1.114) or ITU-T 1992 (Q.771-Q.775) specifications. Use of the TCAP layer also requires use of the TX Series Message Transfer Part (MTP) and Signaling Connection Control Part (SCCP).
- The remainder of this section describes the SS7 software architecture. Subsequent sections of this document describe the general characteristics and operation of the TCAP APIs as well as a detailed specification of the messages and function calls that comprise the APIs.
1.1 SS7 Architecture
- Figure 1 shows the SS7 software architecture in a typical system with separate host applications handling transactions, the system configuration, and system alarms. The system consists of the following components.
- On the TX Series processor:
- The TX Series SCCP task. This task implements the SS7 SCCP layer.
- The TX Series MTP task. This task implements the SS7 MTP-2 (data link)
layer and the MTP-3 (network) layer.
- The (optional) TX Series ISUP task. This task implements the SS7 ISUP
layer.
- The TX Series NETMGR task. This task coordinates all configuration and
management traffic between the host and the SS7 tasks on the TX Series
processor.
- The TX Series Alarms Manager task. This task collects unsolicited alarms
(status changes) generated by the SS7 tasks and forwards them to the host
for application-specific alarm processing.
- On the host:
- A function-call based API which provides the application with a high-level
interface to the TCAP layer services.
- An alarm collector process for capturing alarms and saving them to a text
file. The alarm collector (txalarm) is provided in both executable and
source form. The source may be used as an example for developer's who
wish to integrate the TX Series alarms into their own alarm monitoring
system.
- A set of configuration utilities (one for each SS7 layer) which read the SS7
configuration file(s) and load the configurations to the TX Series processor
tasks at system startup. The TCAP configuration utility (tcapcfg) is
provided in both executable and source form. The source may be used as an
example for developer's who wish to integrate the TCAP configuration into
their own configuration management system.
Figure 1. TCAP System Architecture
1.2 TCAP Layer Services
- The TX Series TCAP layer provides the following services on behalf of applications.
- Assembling of application components (operation invokes and replies) and
parameters into TCAP messages
- Association of replies with invokes
- Optional timing for replies to invokes (ITU-T only)
- Handling of abnormal conditions: protocol errors, timeouts, aborted
transactions
- Use of ITU-T standard TCAP with ANSI-standard MTP/SCCP stack and
vice versa
- The TCAP layer utilizes the SCCP connectionless transport service. In addition to the services described above, the TCAP layer also makes the following SCCP layer services available to the application.
- Subsystem and point code status change indications
- Replicated subsystems with coordinated state change
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