Communication Networks - PragSoft

[Pages:36]Communication Networks

Sharam Hekmat

PragSoft Corporation

Contents

Contents

6

Preface

10

1. Introduction

1

1.1. Network Components

2

1.2. Network Types

2

1.3. The OSI Model

4

1.3.1. The Physical Layer

7

1.3.2. The Data Link Layer

7

1.3.3. The Network Layer

8

1.3.4. The Transport Layer

9

1.3.5. The Session Layer

9

1.3.6. The Presentation Layer

10

1.3.7. The Application Layer

10

1.4. Protocol Notations

11

1.4.1. Service Primitives

11

1.4.2. Sequence Diagrams

12

1.4.3. State Transition Diagrams

12

1.5. Standards

13

1.6. Further Reading

14

1.7. Summary

15

1.8. Exercises

16

2. The Physical Layer

18

2.1. Equipment

19

2.1.1. Equipment Types

19

2.1.2. Connection Types

19

2.2. Transmission

20

2.2.1. Signal Types

20

2.2.2. Modulation

21

2.2.3. Digitization

22

2.2.4. Synchronization

23

2.2.5. Transmission Media

24

2.3. Multiplexing

27

2.3.1. Space Division Multiplexing (SDM)

28

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2.3.2. Frequency Division Multiplexing (FDM)

28

2.3.3. Time Division Multiplexing (TDM)

29

2.3.4. Concentration

29

2.4. Physical Layer Standards

30

2.4.1. RS-232

30

2.4.2. CCITT X.21

32

2.5. Further Reading

33

2.6. Summary

33

2.7. Exercises

34

3. The Data Link Layer

36

3.1 Link Protocol Types

37

3.1.1. Synchronous Protocols

37

3.1.2. Asynchronous Protocols

38

3.1.3. Master-Slave Protocols

38

3.1.4. Peer-to-Peer Protocols

38

3.2. Link Protocol Functions

38

3.2.1. Acknowledgments

39

3.2.2. Timers

39

3.2.3. Error Checking

40

3.2.4. Retransmission

42

3.2.5. Flow Control

42

3.3. Sliding Window Protocol

43

3.4. Data Link Layer Standards

45

3.4.1. BSC

45

3.4.2. HDLC

46

3.5. Further Reading

48

3.6. Summary

49

3.7. Exercises

50

4. The Network Layer

52

4.1. Network Services

53

4.2. Switching Methods

55

4.2.1. Circuit Switching

55

4.2.2. Packet Switching

57

4.3. Packet Handling

59

4.3.1. Packet Structure

60

4.3.2. Routing

60

4.3.3. Congestion Control

63

4.3.4. Error Handling

63

4.4. Internetworking

64

4.4.1. Network Sublayers

65



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4.5. Network Layer Standards

66

4.5.1. CCITT X.25

66

4.5.2. CCITT X.75

69

4.5.3. IP 70

4.5.4. ISO 8473

71

4.6. Further Reading

72

4.7. Summary

72

5. The Transport Layer

65

5.1. Transport Services

65

5.1.1. Network Types

67

5.2. Transport Protocol

67

5.2.1. TPDUs

67

5.2.2. Classes of Protocol

68

5.2.3. Segmentation

69

5.2.4. Multiplexing

69

5.2.5. Splitting and Recombining

69

5.2.6. Addressing

69

5.2.7. Flow Control

70

5.2.8. Error Checking

70

5.3. Transport Layer Standards

70

5.3.1. TCP

71

5.4. Further Reading

72

6. The Session Layer

74

6.1. Session Services

74

6.1.1. Session Layer Role

77

6.1.2. Functional Units

77

6.2. Session Protocol

78

6.2.1. Tokens

79

6.2.2. Activities and Dialogue Units

79

6.2.3. Synchronization

80

6.2.4. Error Reporting and Resynchronization

81

6.2.5. SPDUs

82

6.3. Session Layer Standards

82

6.4. Further Reading

83

7. The Presentation Layer

84

7.1. Presentation Services

84

7.1.1. Syntax

84

7.1.2. Service Primitives

87

7.1.3. Functional Units

89

7.2. Abstract Syntax Notation One

89

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7.2.1. Definitions in ASN.1

89

7.2.2. Basic Encoding Rules

91

7.3. Presentation Protocol

93

7.4. Presentation Standards

94

7.5. Further Reading

94

8. The Application Layer

95

8.1. Application Services

95

8.1.1. Application Entity

96

8.2. Common Application Service Elements

97

8.2.1. Association Control

97

8.2.2. Reliable Transfer

97

8.2.3. Remote Operations

98

8.3. Specific Application Service Elements

98

8.3.1. Virtual Terminal

98

8.3.2. Message Handling Systems

100

8.3.3. File Transfer, Access, and Management

104

8.4. Other Standards

108

8.5. Further Reading

108

9. Local Area Networks

109

9.1. Basic Concepts

109

9.1.1. Topologies and Access Protocols

110

9.1.2. Architecture

112

9.1.3. Transmission

113

9.2. IEEE 802 Standards

113

9.2.1. Logical Link Control

114

9.2.2. CSMA/CD

115

9.2.3. Token Bus

116

9.2.4. Token Ring

117

9.3. ANSI FDDI Standard

118

9.3.1. Topology

118

9.3.2. Token Ring Protocol

119

9.4. Further Reading

120

10. Telephone Networks

121

10.1. Basic Concepts

121

10.1.1. A Simple Network

122

10.1.2. Networks Topologies

123

10.1.3. Switching Systems

125

10.2. Signaling

126

10.2.1. Subscriber Signaling

127

10.2.2. Interexchange Signaling

128



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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



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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.

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