Oryal Tanir, V.K.Agarwal and P.C.P. Bhatt BELL CANADA Quality Engineering & Research Laboratories, 2265 Roland Therrien Blvd. Longueuil, Quebec J4N 1C5 CANADA E-mail: OTANIR@QC.BELL.CA
Asynchronous Transfer Mode (ATM) is an emerging technology which will play a significant role within our industry. It is the only standard that will fuse broad band data communication requirements with switching technology. As such, its impact within the telecommunication and data communication industries will be major. Currently in its infancy, the implications of the technology will be more evident in the next few years. One of the major applications of ATM will be to serve as the backbone and enabling technology for multimedia systems.
The design and modelling of ATM systems presents some interesting challenges that traditional networks did not possess. For example, traffic patterns across ATM based multimedia networks are difficult to model analytically due to interdependent data streams as well as very different traffic characteristics of the data. Assumptions and simplification are useful in modelling only a small subset of relatively simple ATM designs. Hence simulation is currently used to model large networks where assumptions must be minimized. Simulation in itself, poses problems such as simulation times, output data complexity, and design exploration. The implication is that an architectural design environment would be beneficial to provide the necessary support and model management of the simulation activities. Such an environment is DASE: (Design and Synthesis Environment).
McGill University has developed DASE for architectural modelling, simulation, design exploration and synthesis of telecommunication systems. Design alternatives can be modelled, simulated and analysed until a desired design objective is achieved using abstract models to generate and synthesize more detailed ones which can be used by lower level design aids.
DASE allows telecommunication designers to experiment with different design options and trade-offs at a significantly abstract but intuitive architectural representation level. Design specifications are entered through a user interface and captured by the environment through the use of an internal Design Specification Language (DSL) and supported by an object oriented library system. DSL models comprise of message passing object-oriented entities called modules which are abstract building blocks that capture behaviour, hierarchy, inheritance, constraints and data used to store local variables, registers or state information.
Object-oriented Library support features allow for the creation, storage and retrieval of module libraries in an organized manner.The language allows constraints to be defined which establish limits upon the structure and behaviour of modules. In design exploration, DASE searches for alternate design modules from an existing model base as required by the designer. The environment capabilities are illustrated with the design of an ATM switch based network suitable for multimedia applications.