n Tiburtius and Ingvar Wikström. Thanks also to Mikael Rohnstrom who was the first to use AML in his own project. I also feel grateful to the Ericsson company and all its managers who have sup- ported my research over the years, particularly Pierre Boucher, Jan Gunnelin, Mar- tin Hänström, Lars Lindroos, Jorma Mobrin, Nam Nguyen, Per-Olof Sundgren and Claus Wildling. Special thanks are also due to Hans Borgnäs, who supported me while I wrote this book. Stockholm Thomas Muth December 2000 Contents 1 Introduction to Systems Modelling 1.1 Why Another Modelling Language? 1.2 Why Modelling Systems Is important System Abstractions Processing Systems System Models 1.5.1 The Structure of System Models 1.5.2 Fragmenting Sysnet Models 1.5.3 Fragmenting Implemented System Models 1.5.4 How Implemented and Applied System Models Are Related 1.6 Requirements on a Modelling Language for Systems Modelling 1.6.1 Semantic Distance 1.6.2 Syntactical Style 1.6.3 Model Structure Representation 1.6.4 Expressive Value 1.6.5 Completeness 1.7 Summary 2 Foundations of Sysnet Modelling 2.1 Introduction Focus on Telecom Systems and Networks 2.2.1 The Logical Network View on Telecom Systems 2.2.2 Communication Service Provider 2.2.3 Physical Networks and Physical Nodes 2.2.4 The Physical Network View on Telecom Systems 2.2.5 Sysnet Models Contents 2.3 Architectural Principles 2.3.1 Abstraction Hierarchy 2.3.2 The Dualism Between Interface and Unit 2.3.3 Interface Refinement 2.3.4 Substructures 2.3.5 Interface Transformation 2.3.6 Functional Space 2.3.7 Integration Hierarchy 2.3.8 Concepts Summary 2.4 Implementation Independent Models 2.5 Views and Visualization Modes Principles of Graphical Notations in AML 2.7 Summary 3 Logical Network Modelling 3.1 Introduction 3.2 The Communication Service Provider 3.2.1 Introduction 3.2.2 The OSI Service Provider 3.2.3 The CSP in AML 3.2.4 Summary of Network Service Interface Notations 3.2.5 Service Access Point Operations 3.3 Network Service Interface Scenarios 3.3.1 Circuit Switched Services 3.3.2 Packe