Communication networks : principles and practice

M c G R A W - H I L L COMMUNI CATI ONS

COMMUNICATION

NETWORKS

Principles

and Practice

SUMIT KASERA,

NISHIT NARANG,

SUMITA NARANG

COMMUNICATION

NETWORKS

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COMMUNICATION

NETWORKS

Principles and Practice

Sum it Kasera

Nishit N arang

Sumita N arang

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To

Raj, my naughty little prince charm ing

• Sumit Kasera

Ramesh Narang, my father and m entor

• Nishit Narang

Saroj Narang, my mother-in-law, who is also my role model

• Sumita Narang

PREFACE

Origin

The origin of this book lies in the first edition of the book A I'M Networks:

Concepts and Protocols by Sumit Kasera. ATM Networks comprises both

the basic concepts of networking as well as the details of ATM networks.

The organization of the book made many reviewers opine that the target

audience was unclear, largely because it incorporated, in one book,

material that was too technical for beginners and material that was too

basic for experts. It was clear therefore, that the basic concepts of

networking demanded another form.

The options were not many. They could be deleted from the book,

and hence, lost forever. Alternatively, they could be posted on the

internet, in what would inevitably be a rather raw form. The third

choice was to put in some effort on the contents, to give it a meaningful

shape in the form of a book. To decide on which would be the best

option, a quick survey was conducted among the readers of the book:

Gurpreet Singh, Yogesh Garg, Paras Shah, and L. Sreenivasan were

those who provided valuable comments. They were unanimous that the

basic concepts should not be lost and that breaking the book into two

separate books was a better idea by far. This verdict led to the birth of

the second edition o f ATM Networks focusing only on ATM technology;

and a second book— a new book— on Communication Networks: Principles

and Practice.

To fulfill the latter objective, the three of us came together, to co￾author this project. Our task was made easier because we are colleagues

at that great organization, Flextronics Software Systems, which has a vast

knowledge base in the field of networking and communication.

Scope

Without any doubt there are a plethora of books in the field of data

communications, networking, and computer networks. And without any

v iii Preface

doubt, many of them are written by great academicians and are

extremely good books. We have had the opportunities to read and learn

from these books. Given this, it was important for us to ask ourselves

whether there was a genuine need for another book. If yes, what

purpose would this book fulfill?

One clear need (or demand) for most readers is to have a book that

is simple and fairly easy to read. However, as with the first edition of

ATM Networks, most good books are comprehensive and cover many

topics that people might not like to read. This is especially true for first

time readers. Thus, a clear need emerges for a book that is easy to read,

simple to understand, without jargon, and covering most of the impor￾tant topics of communication networks (if not all). It is this need that our

new book tries to fulfill. This book has a fairly simple language, covers

only key concepts, does not attempt to cover networking protocols in any

detail (except as examples to illustrate a point) and is not very thick. We

hope therefore, that reading the book from cover to cover will not task

our readers for time.

To this end, the authors have adopted many novel techniques. First

of all, the focus is on concepts, not on technologies. Further, the

chapters are not based on the OSI reference model, thus providing a

greater flexibility to the organization of the contents. The book is

planned such that each chapter first provides details of a particular

aspect of networking (e.g. Routing) and then explains it further by using

examples of a contemporary technology (like TCP/IP, ATM or even 3G

Network). This approach allows the reader to learn the concepts and

further helps him with actual realization in a popular technology. For

more details, there are several good books on each individual

technology that are mentioned in the Further Reading section. To

summarize, this book tries to build a base for understanding the basic

concepts of communication networks.

Many categories of people will find this book useful. These include

students of basic courses on computer networks or data

communications. Students taking advance courses will find it handy for

revising basic concepts of networking. This book will also be of value to

fresh telecom professionals coming from non computer-science

background and lacking relevant experience.

Here, without any iota of doubt, it may be said that this new book does

not diminish the utility of the existing good books. It only makes the

reading of other books easier. It does not aspire to replace them.

About the Book

Most books on computer networks are typically based on the OSI

reference model. Thus, they cover the seven layers or building blocks

Preface ix

of communication networks. This OSI model is a fairly old concept and

most of its principles have undergone modifications. Moving away from

the OSI model, this book looks at several key concepts of networking

and explains them w ith relevant examples. The concepts are divided in

three Parts (see Fig. P. 1).

Part 1 provides an introduction to the building blocks of communica￾tion networks. In this part, Chapter 1 provides an overview of

connection-oriented and connectionless services and explains why these

concepts are important. Chapter 2 provides an overview of protocol

layering principles, including the OSI reference model. Chapter 3 then

elaborates on the concept of transfer modes (including circuit sw itching

and packet switching). This concept is tightly linked to the nature of

network services (i.e. connection-oriented and connectionless services).

Chapter 4 discusses some of the aspects related to network topology and

extent.

Part 2 uses the building blocks of networks as discussed in Part 1 to

elaborate upon seven core concepts of networking. Chapter 5 discusses

physical layer aspects like transmission and multiple access. Chapter 6

looks at data link layer functionality and discusses issues like access

resolution, sliding window protocol, flow control and error control.

Chapter 7 looks at the means for connecting different networks together,

a process referred to as bridging. Chapter 8 looks at switching issues

and switch architectures. Chapter 9 elaborates upon the types of

addressing and the relevance of addressing. Chapters 10 and 11 talk

Fig. P.1 Organization of the book

x Preface

about signalling and routing. Typically, addressing, signalling, and

routing go together (and are typically applicable at the network layer).

Part 3 takes the discussion forward and touches upon three more

concepts. The concept of traffic and traffic management is discussed in

Chapter 12. The network management aspects are covered in Chapter

13 and security related issues and solutions are discussed in Chapter 14.

Web Site

To better interact with readers after the publication of this book, the authors

have created a web site http://nwbook.tripod.com and a mirror web site man￾aged by the publisher http://www.tatanicgrawhill.com/digital_solutions/

sumitnishit. These web sites offers the following:

• Preface

• Table of Contents

• Errata

• Feedback and Review Comments

• References

• Other Related Material

Readers are encouraged to visit the web site and use the available

material.

Suggestions

Your comments, feedback, and constructive criticism are valuable to us;

so, please feel free to drop an email at [email protected]. We would be

glad to incorporate your comments in the subsequent editions of the

book.

S u m i t K a s e r a

N i s h i t N a r a n g

S u m i t a N a r a n g

CONTENTS

P reface

A bbreviations

Part 1

I Building Blocks o f Communication Networks

1. Network Services

1.1 Introduction 5

1.2 Connection-oriented Service 5

1.3 Connectionless Service 6

1.4 Connection-oriented versus

Connectionless Service 8

1.5 Examples 10

1.6 Conclusion 11

Review Questions 11

Further Reading 11

2. Protocol Layering

2.1 Introduction 12

2.2 Layered Architecture 13

2.3 Services, Interface, Primitives and

Service Access Points 14

2.4 Open Systems Interconnection￾Reference Model (OSI-RM) 18

2.5 Definition of Open System 20

2.6 Seven-layered OSI-RM 20

2.7 Shortcomings of the OSI-RM Reference Model 26

2.8 Example: TCP/IP Protocol Suite 27

2.9 Conclusion 35

Review Questions 35

Further Reading 36

Contents

Transfer Modes

3.1 Introduction 37

3.2 Circuit Switching 38

3.3 Routing 40

3.4 Virtual Circuit Switching 42

3.5 Comparison ofTransfer Modes 45

3.6 Example: Asynchronous Transfer Mode (ATM) 48

3.7 Conclusion 56

Review Questions 57

Further Reading 57

Network Topology and Extent

4.1 Introduction 58

4.2 Network Topology 58

4.3 Network Extent 60

4.4 Local Area Networks (LAN) 61

4.5 Wide Area Network (WAN) 63

4.6 Other Area Networks 64

4.7 Examples 65

4.8 Conclusion 66

Review Questions 66

Further Reading 66

Part 2

I Core Concepts o f Com m unication Networks

Transmission and Multiple Access

5.1 Introduction 71

5.2 Transmission Concepts 71

5.3 Multiple Access Concepts 80

5.4 Example: EDMA/TDMA in GSM Networks 84

5.5 Example: CDMA in UMTS Networks 86

5.6 Conclusion 93

Review Questions 93

Further Reading 94

Data Link Control

6.1 Introduction 95

6.2 Data Link Line Configurations 95

6.3 Data Link Layer Functions 97

6.4 Services Offered to Network Layer 104

6.5 DLC Protocol Layering 106

6.6 Logical Link Control (LLC) 107

6.7 Media Access Control (MAC) 111

Contents x iii

6.8 Flow Control Protocols 119

6.9 Error Detection and Correction Mechanisms 123

6.10 Example: HDLC 130

6.11 Conclusion 134

Review Questions 134

Further Reading 135

7. Bridging 137

7.1 Introduction 136

7.2 Transparent Bridging 137

7.3 Source Route Bridging 142

7.4 Example: Bridging in Ethernet LANs 144

7.5 Conclusion 146

Review Questions 146

Further Reading 147

8. Switching 148

8.1 Introduction 148

8.2 Components of a Typical Switch 149

8.3 Performance Measures in Switch Design 150

8.4 Switching Issues 152

8.5 Switching Architectures 165

8.6 Shared-memory Architecture 165

8.7 Shared-medium Architecture 168

8.8 Space-division Architecture 169

8.9 Example: Switching in ATM 179

8.10 Example of ATM Switch Architecture:

Knockout Switch 184

8.11 Conclusion 191

Review Questions 191

Further Reading 191

9. Addressing 192

9.1 Introduction 192

9.2 Classification of Addressing Techniques 193

9.3 Example: Addressing Structure in Internet 197

9.4 Example: Addressing Structure in

Telecom Networks 199

9.5 Conclusion 200

Review Questions 201

Further Reading 201

10. Signalling 202

10.1 Introduction 202

10.2 Signalling Complexity in Different Networks 203

x iv Contents

10.3 Classification of Signalling Techniques 204

10.4 Signalling Issues 207

10.5 Signalling Models 215

10.6 Point-to-multi-point Signalling 216

10.7 Example: ISDN Signalling 220

10.8 Conclusion 226

Review Questions 226

Further Reading 226

11. Routing

11.1 Introduction 227

11.2 Design Requirements for a Routing Protocol 229

11.3 Classification of Routing Protocols/Techniques 231

11.4 Core Routing Concepts 235

11.5 Example: Routing Protocols in Internet 242

11.6 Conclusion 254

Review Questions 254

Further Reading 254

Part 3

I Advanced Concepts o f Communication Networks

12. Traffic Management

12.1 Introduction 259

12.2 Concept of Traffic 260

12.3 Concept of Service 262

12.4 Network Capabilities 264

12.5 Types ofTraffic 266

12.6 Traffic Management 269

12.7 Traffic Contract Management 270

12.8 Traffic Shaping 272

12.9 Traffic Policing 274

12.10 Priority Control 276

12.11 Flow Control 277

12.12 Congestion 278

12.13 Congestion Control 282

12.14 Flow Control versus Congestion Control 286

12.15 Example: Traffic Management in ATM 287

12.16 Conclusion 301

Review Questions 301

Further Reading 302

227

259

13. Network Management

13.1 In tr o d u c tio n 303

303