Data communications and networks

563 Pages·2011·16.143 MB·English

by  Atul Kahate, Achyut S. Godbole

Data Communications
and Networks
Second Edition
About the Authors
Achyut Godbole is currently the Managing Director of Softexcel Consultancy
Services, Mumbai. His professional career spans 32 years, and during this
time, he has served in world-renowned software companies in India, UK and
USA. He has contributed to the multifold growth of companies such as Patni,
Syntel, L&T Infotech, Apar, Disha, etc. He did his BTech from IIT Bombay in
Chemical Engineering, and henceforth, worked for the welfare of Adivasi tribes
in Maharashtra, for a year.
Mr Godbole has authored best-selling textbooks from Tata McGraw-Hill such as
Operating Systems, Data Communications and Networking, and Web Technologies,
including international editions and Chinese translations. In addition, he has authored several very-highly
rated books on various subjects (such as computers, management, economics, etc.) in Marathi and has
written several popular columns in Marathi newspapers/magazines on science, literature, medicine, and
technology. He has conducted numerous programmes on television pertaining to technology, science,
and economics.
He has won several awards, including an award from the Prime Minister of India, ‘Udyog Ratna’,
‘Distinguished Alumnus’ from IIT, ‘Kumar Gandharva’ award from Pandit Bhimsen Joshi, ‘Navaratna’
from Sahyadri TV channel, the ‘Indradhanu Puraskar’, and ‘Parnerkar Puraskar’ for his contributions to
the fi eld of economics. Besides, he was ranked 16th in merit in Maharashtra State Board Examinations.
A brilliant student, he has won several prizes for distinguished performance in Mathematics as well. He
also runs a school for autistic children.
He has a website (www.achyutgodbole.com) and can be reached at [e-mail].
Atul Kahate is working with Oracle Financial Services Software Limited as Senior
Consultant. He has been associated with this organisation for over a decade. He
has 16 years of experience in Information Technology in India and abroad in
various capacities. Previously, he has worked with Syntel, L&T Infotech, American
Express and Deutsche Bank. He has a Bachelor of Science degree in Statistics and
a Master of Business Administration in Computer Systems.
Mr Kahate has authored 28 highly acclaimed books on Technology, Cricket,
and History published by Tata McGraw Hill, and other reputed publications. Some of these titles include
Web Technologies—TCP/IP to Internet Application Architectures, Cryptography and Network Security,
Fundamentals of Computers, Information Technology and Numerical Methods, Introduction to Database
Management Systems, Object Oriented Analysis and Design, and Schaum’s Series Outlines—Programming
in C++, XML and Related Technologies. Two of these have been published as international editions by
Tata McGraw-Hill and have been translated into Chinese. Several of his books are being used as course
textbooks or sources of reference in a number of universities/colleges/IT companies all over the world. He
has authored two books on cricket, and has written over 3000 articles on IT and cricket in leading Marathi
newspapers/magazines/journals in India and abroad.
He has deep interest in history, science, economics, music, cricket, and teaching, besides technology.
He has conducted several training programs in a number of educational institutions and IT organizations
on a wide range of technologies. He has done a series of programmes for many TV channels for explaining
complex technologies to a common viewer in a simplifi ed manner.
Mr Kahate has won several awards, both in India and abroad, including the Computer Society of India
(CSI) award for IT education and literacy, the noted ‘Yuvonmesh Puraskar’ from Indradhanu–Maharashtra
Times, and the ‘IT Excellence Award’ from Indira Group of Institutes.
He has a website (www.atulkahate.com) and can be reached at [e-mail].
Data Communications
and Networks
Second Edition
ACHYUT S GODBOLE
Managing Director
SoftExcel Services Limited, Mumbai
ATUL KAHATE
Senior Consultant
Oracle Financial Services Software Limited, Pune
Tata McGraw Hill Education Private Limited
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Data Communications and Networks, 2e
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Contents
Preface xv
1. Introduction to Data Communications and Networking 1
1.0 Introduction 1
1.1 Fundamental Concepts 1
1.2 Data Communications 3
1.3 Protocols 4
1.4 Standards 4
1.5 Standards Organizations 5
1.6 Signal Propagation 6
1.7 Analog and Digital Signals 8
1.8 Bandwidth of a Signal and a Medium 9
1.9 Fourier Analysis and the Concept of Bandwidth of a Signal 13
1.10 Data Transmission Rate and Bandwidth 18
Summary 20
Key Terms and Concepts 21
Questions 21
2. Analog and Digital Transmission Methods 24
2.0 Introduction 24
2.1 Analog Signal, Analog Transmission 24
2.2 Digital Signal, Digital Transmission 24
2.3 Digital Signal, Analog Transmission 26
2.4 Baud Rate and Bits Per Second 30
2.5 Analog Signal, Digital (Storage and) Transmission 32
2.6 Nyquist Theorem 34
Summary 36
Key Terms and Concepts 37
Questions 37
3. Modes of Data Transmission and Multiplexing 40
3.0 Introduction 40
viii
Contents
3.1 Parallel and Serial Communication 40
3.2 Asynchronous, Synchronous and Isochronous Communication 42
3.3 Simplex, Half-duplex and Full-duplex Communication 46
3.4 Multiplexing and Demultiplexing 50
3.5 Types of Multiplexing 50
3.6 FDM versus TDM 57
Summary 57
Key Terms and Concepts 59
Questions 59
4. Transmission Errors: Detection and Correction 62
4.0 Introduction 62
4.1 Error Classifi cation 62
4.2 Types of Errors 63
4.3 Error Detection 63
Summary 75
Key Terms and Concepts 76
Questions 76
5. Data Compression and Encryption 78
5.0 Introduction 78
5.1 Simple Coding Scheme 78
5.2 Based on the Context of Symbols 79
5.3 Based on the Relative Frequencies of Symbols 80
5.4 Information Security 85
5.5 Cryptography 87
5.6 Symmetric and Asymmetric Key Encryption 89
5.7 Digital Certifi cates 93
5.8 Digital Signatures 94
5.9 Secure Socket Layer (SSL)/Transport Layer Security (TLS) 95
5.10 Firewalls 97
5.11 Email Security 99
Summary 102
Key Terms and Concepts 103
Questions 103
6. Transmission Media 106
6.0 Introduction 106
6.1 Guided Media 106
6.2 Unguided Media 111
6.3 Shannon Capacity 120
Summary 121
Key Terms and Concepts 121
Questions 122
ix
Contents
7. Network Topologies, Switching and Routing Algorithms 124
7.0 Introduction 124
7.1 Mesh Topology 124
7.2 Star Topology 125
7.3 Tree Topology 125
7.4 Ring Topology 127
7.5 Bus Topology 128
7.6 Hybrid Topology 128
7.7 Basics of Switching 130
7.8 Router and Routing 136
7.9 Routing Algorithms 139
Summary 121
Key Terms and Concepts 149
Questions 122
8. Networking Protocols and OSI Model 153
8.0 Introduction 153
8.1 Protocols in Computer Communications 155
8.2 The OSI Model 159
8.3 OSI Layer Functions 163
8.4 Queuing Theory and M/M/1 Queues 172
Summary 172
Key Terms and Concepts 173
Questions 174
9. Local Area Networks (LAN), Metropolitan Area Networks (MAN) and
Wide Area Networks (WAN) 176
9.0 Introduction 176
9.1 Local Area Networks (LAN) 177
9.2 Ethernet 177
9.3 Virtual LAN (VLAN) 184
9.4 Fast and Gigabit Ethernet 186
9.5 Token Ring 188
9.6 Fiber Distributed Data Interface (FDDI) 192
9.7 Comparison of Ethernet, Token Ring and FDDI 195
9.8 Metropolitan Area Network (MAN) 195
9.9 Distributed Queue Dual Bus (DQDB) 195
9.10 Switched Multimegabit Data Services (SMDS) 198
9.11 Wide Area Network (WAN) 199
9.12 WAN Architecture 200
9.13 WAN Transmission Mechanism 201
9.14 WAN Addressing 202
9.15 Packet Forwarding 203
9.16 Next-hop Tables and Routing 205
9.17 Pure and Slotted ALOHA 206
x
Contents
Summary 207
Key Terms and Concepts 208
Questions 209
10. Medium Access Sublayer and ISDN 212
10.0 Introduction 212
10.1 Static and Dynamic Channel Allocation 212
10.2 Medium Access Control (MAC) Sublayer 214
10.3 MAC in LAN and WAN 215
10.4 Classifi cation and Study of MAC Sublayer Protocols/Collisions 216
10.5 ISDN and Its Background 217
10.6 ISDN Architecture 219
10.7 ISDN Interfaces 221
10.8 Functional Grouping 223
10.9 Reference Points 225
10.10 ISDN Protocol Architecture 225
10.11 Narrowband-ISDN (N-ISDN) and Broadband ISDN (B-ISDN) 231
Summary 231
Key Terms and Concepts 232
Questions 232
11. X.25 Protocol 235
11.0 Introduction 235
11.1 Understanding How X.25 Works 235
11.2 Characteristics of X.25 238
11.3 Packet Format 240
11.4 X.25 Operation 243
11.5 CCITT X.21 245
Summary 246
Key Terms and Concepts 246
Questions 246
12. Frame Relay and Congestion Control 248
12.0 Introduction 248
12.1 The Need for Frame Relay 248
12.2 How Frame Relay Works 253
12.3 Frame Relay Frame Format 256
12.4 Congestion Control 257
12.5 Congestion Control Algorithms 258
12.6 Traffi c Control 260
12.7 Frame Relay Assembler/Disassembler (FRAD) 261
12.8 Other Features 261
Summary 261
Key Terms and Concepts 262
Questions 262
xi
Contents
13. Asynchronous Transfer Mode (ATM) 265
13.0 Introduction 265
13.1 Overview of ATM 266
13.2 Packet Size 268
13.3 Virtual Circuits in ATM 270
13.4 ATM Cells 272
13.5 Switching 273
13.6 ATM Layers 276
13.7 Miscellaneous Topics 281
Summary 283
Key Terms and Concepts 284
Questions 284
14. Wireless Communication 287
14.0 Overview of Wireless Networks 287
14.1 IEEE Standards for LAN, MAN, and WAN – 802.1, 802.2, 802.3, 802.4, 802.5,
802.11 288
14.2 Infrared Communication 290
14.3 Bluetooth 291
14.4 802.11 Wireless LAN 298
Summary 305
Key Terms and Concepts 305
Questions 306
15. Internetworking Concepts, Devices, Internet Basics, History and Architecture 308
15.0 Introduction 308
15.1 Why Internetworking? 309
15.2 Problems in Internetworking 309
15.3 Dealing with Incompatibility Issues 310
15.4 A Virtual Network 313
15.5 Internetworking Devices 314
15.6 Repeaters 315
15.7 Bridges 316
15.8 Routers 321
15.9 Gateways 324
15.10 A Brief History of the Internet 325
15.11 Growth of the Internet 327
15.12 Internet Topology 329
15.13 Internal Architecture of an ISP 331
Summary 335
Key Terms and Concepts 336
Questions 337
16. Ways of Accessing the Internet 340
16.0 Introduction 340