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10.2.3. Common Channel Signaling 129
10.3. Signaling System Number 7 131
10.3.1. Signaling Data Link 132
10.3.2. Signaling Link Control 132
10.3.3. Signaling Network Functions 133
10.3.4. Signaling Connection Control Part 134
10.3.5. User Parts 135
10.3.6. Operations and Maintenance Applications Part 136
10.4. Private Telephone Networks 136
10.4.1. PBX Networks 136
10.4.2. Corporate Networks 137
10.4.3. Intelligent Networks 138
10.5. Further Reading 139
11. Integrated Services Digital Network 140
11.1. Basic Concepts 140
11.1.1. ISDN Channels 141
11.1.2. Functional Groupings and Reference Points 142
11.1.3. ISDN Services 144
11.2. Protocol Architecture 145
11.2.1. The Physical Layer 146
11.2.2. The Data Link Layer 148
11.2.3. The Network Layer 151
11.3. Frame Relay 154
11.3.1. V.120 155
11.3.2. Frame Relay 156
11.4. Internetworking 157
11.5. ISDN Standards 158
11.6. Further Reading 159
12. Broadband ISDN and ATM 161
12.1. Broadband ISDN 161
12.1.1. B-ISDN Services 161
12.1.2. B-ISDN User-Network Interface 163
12.1.3. B-ISDN Protocol Architecture 164
12.2. Asynchronous Transfer Mode 165
12.2.1. Channels and Paths 165
12.2.2. ATM Cells 167
12.3. Physical Layer 168
12.3.1. SDH-Based Interface 168
12.3.2. Cell-Based Interface 169
12.3.3. Cell Delineation 170
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12.3.4. HEC Generation and Verification 171
12.3.5. Cell Rate Decoupling 171
12.4. ATM Layer 172
12.4.1. Generic Flow Control 172
12.4.2. Virtual Path Identifier 172
12.4.3. Virtual Channel Identifier 172
12.4.4. Payload Type 173
12.4.5. Cell Loss Priority 173
12.5. ATM Adaptation Layer 173
12.5.1. Segmentation and Reassembly Sublayer 174
12.5.2. Convergence Sublayer 175
12.6. B-ISDN Standards 175
12.7. Further Reading 175
Bibliography 160
x Communication Networks
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Preface
This book is concerned with post-computer communication networks and two of its important streams: data communication and telecommunication. Data communication
refers to the communication between digital computers, facilitated by computer networks. Telecommunication refers to the primarily human-to-human
communication facilitated by the global telephone system. The differences between these two streams are mainly due to historical reasons. Telecommunication is
increasingly relying on digital computer technology, and data communication is relying more than ever on telecommunication networks. The two streams are rapidly
converging.
Newcomers to this field are often bewildered by the substantial wealth of information already published on the subject. This book is aimed at this group of
people. It provides a broad coverage of the key concepts, techniques, and terminology, so as to prepare readers for more advanced discussions. In-depth
discussions of technically-involved topics are intentionally avoided in favor of more general concepts. No previous knowledge of networks or programming is assumed.
The structure of the book is as follows. Chapter 1 introduces computer networks and explains some of their elementary concepts. It also introduces the OSI reference
model, upon which later chapters are based. Each of Chapters 2-8 describes one of the seven layers of the OSI model in the context of wide area data networks.
Chapter 9 looks at local area networks and their applications. Chapter 10 provides an introduction to telecommunication. Chapter 11 builds on earlier chapters by
examining ISDN as the merging point of data and voice networks. Chapter 12 looks at the ATM technology and the potential applications that it can support.
www.pragsoft.com Chapter 1: Introduction
