telstra_sultan
SULTAN (SUbscribers Line Test Access Network) is Telstra’s national system for remote testing and fault diagnosis of PSTN (Public Switched Telephone Network) services, principally the CAN (customer access network), CPE (customer premise equipment) and the associated exchange inlet. SULTAN also supports the testing of a subset of Integrated Switched Digital Network (ISDN) lines, namely those built into PSTN nodes as part of the network switch. These are the Basic Rate Access ISDN lines. It allows a testing officer to remotely access the customer’s service and request tests to be performed on the service to determine the condition of the line (CAN), the customer’s equipment (CPE) and the associated inlet to the Exchange. In the event of a fault condition being detected, aid the testing officer in isolating the cause of the fault and the repair area to which the fault should be directed Until the introduction of SULTAN in the early 1980's, line testing was performed only by technical personnel using test desks, hardwired electrical devices which presented analogue line test results either as tones or as voltmeter readings. The electrical measurements made on a telephone line with a test desk often gave an unclear indication of the presence and location of a fault, resulting in many fault repair staff being incorrectly despatched. Test desks had direct access to lines in only the local exchange area, necessitating the involvement of one local and at least one remote Tester in testing more distant lines. With the emergence of data processing and exchange control computer systems in Telstra, it was recognised that a software controlled line testing system would offer significant advantages over the analogue system, including more accurate fault diagnosis, improved operator efficiency, the possibility of integration with related customer information systems, and much greater flexibility for the addition of new features and design changes. Thus, the Subscribers Line Test Access Network (SULTAN) system was conceived in the mid 1970's and implemented in the early 1980’s. The minicomputers chosen originally for SULTAN were DEC PDP-11 machines running the RSX operating system. Application software was written in the assembler language, MACRO-11. Over the life of the SULTAN project the computer hardware and software have been replaced in several stages with more modern equivalents as necessary and as the ongoing program of maintenance and new design work permitted. During the mid 1980's Pascal replaced assembler in the predecessor of the SULTAN Communications Controller (SCC). By 1987, the limited capacity and downgrading of manufacturer support for the PDP-11 necessitated a minicomputer change. The DEC MicroVAX series, running the VMS operating system was the chosen replacement for the Tester Communications Controller (TCC). Pascal code was ported across to the MicroVAX with appropriate changes for operating system and language compiler differences. The volume and complexity of application software steadily increased as a result of the expanding range of test devices with which SULTAN was required to interface and facilities which it was expected to provide. It became apparent that the SULTAN software needed to be restructured so that each user and test technology type would be handled distinctly from others. Additionally, object-oriented techniques through the use of the C++ programming language were adopted as a future standard to improve code maintainability. In order to overcome the hardware restrictiveness of a proprietary operating system, UNIX was chosen. Beginning in 1990, an attempt was made to redevelop a part of the application software in C++. The target platform was the DEC Alpha, a RISC machine, running DEC UNIX. The redevelopment, low in priority and taking almost three years to complete, was unable to keep pace with SULTAN functionality and network architecture changes that had occurred in the meantime. It served as a useful prototype, but was rendered obsolete and never implemented. Due to a pressing works programme, it was not until 1996 that a proposal to completely re-architecture SULTAN was approved and development commenced. This project necessitated full involvement of the development team. Apart from a handful of essential functionality changes, enhancements to production software would cease until completion of the Re-architecture. The C++ / UNIX / Alpha environment was confirmed. The Re-Architecture was implemented in several stages, progressively introducing the XCC, SCC and ICC, whilst retiring the old platforms. A Stage 3 re-architecture was implemented, where the existing Object Store database was replaced by an Oracle database, and some design changes were incorporated by removing ICC as a separate module, and fitting it into the SCC as a separate process, and SULTAN was ported to run on two HP RP 8400 load shared machines. *XCC = translation communication controller. TTP/1.1 200 OK Date: Sun, 14 May 2006 10:35:56 GMT Server: Apache Content-Type: text/html; charset=UTF-8 Keep-Alive: timeout=15, max=94 Connection: Keep-Alive Transfer-Encoding: chunked 1ff8
0 HTTP/1.1 200 OK Date: Sun, 14 May 2006 10:35:56 GMT Server: Apache ETag: W/"904-1117693781000" Last-Modified: Thu, 02 Jun 2005 06:29:41 GMT Content-Type: image/gif Content-Length: 904 Keep-Alive: timeout=15, max=93 Connection: Keep-Alive GIF89al
