Network integration testing: concepts, test specifications and tools for automatic telecommunication services verification

The purpose of this tutorial is to provide concepts and historical backgrou nd of the "network integration testing" (NIT) methodology. NIT is a "grey b ox" testing technique that is aimed at verifying the correct behaviour of i nterconnected networks (operated by different operators) in provisioning se rvices to end users, or the behaviour of a complex network operated by a un ique operator. The main technical concepts behind this technique are presen ted along with the history of some International projects that have contrib uted to its early definition and application. European Institute for Resear ch and Strategic Studies in Telecommunication (EURESCOM) has actually been very active, with many projects, in defining the NIT basic methodology and providing actual NIT specifications (for narrow-band and broad-band service s, covering both voice and data). EURESCOM was also been acting as a focal point in the area, e.g., encouraging the Industry in developing commercial tools supporting NIT. In particular, the EURESCOM P412 project (1994-1996) first explicitly defined the NIT methodology (the methodological aspects in clude test notation, test implementation, test processes, distributed testi ng and related co-ordination aspects). P412 applied the methodology to ISDN whilst another project, P410, applied NIT to data services. The P613 proje ct (1997-1999) extended the basic NIT methodology to the broad band and GSM . More into details, the areas covered currently by NIT test specifications developed by EURESCOM projects include N-ISDN, N-ISUP, POTS, B-ISDN, B-ISU P, IP over ATM, ATM/FR, GSM, focusing also on their "inter-working" cases ( e.g., ISDN/ISDN, ISDN/GSM, etc.). ETSI, the European Telecommunication Stan dards Institute, also contributed to NIT development (e.g., the definition of the TSPl+ protocol, used for the functional co-ordination and timing syn chronisation of all tools involved in a distributed testing session). The p aper also discusses NIT in relation to the recent major changes (processes) within the telecommunication (TLC) community. Beyond the new needs coming from the pure technical aspects (integration of voice and data, fixed mobil e convergence, etc.) the full deregulation of the TLC sector has already ge nerated new processes and new testing needs (e.g., Interconnection Testing) that had a significant influence on the methodology. NIT is likely to cont inue to develop further in the future according to the needs of telecom ope rators, authorities, user's associations and suppliers. (C) 2000 Elsevier S cience B.V. All rights reserved.