Communication Networks - PragSoft

1 CommunicationNetworksSharam HekmatPragSoft NetworksCopyright 2005 PragSoftContentsContents6 Preface101. network network The OSI The Physical The Data Link The network The Transport The Session The Presentation The Application Protocol Service Sequence State Transition Further Exercises162. The Physical Equipment Connection Signal Transmission Space Division Multiplexing (SDM) Frequency Division Multiplexing (FDM) Time Division Multiplexing (TDM) Physical Layer CCITT Further Exercises343. The Data Link Link Protocol Synchronous Asynchronous Master-Slave Peer-to-Peer Link Protocol Error Flow Sliding Window Data Link Layer Further Exercises504.

2 The network network Switching Circuit Packet Packet Packet Congestion Error network Sublayers65viiiCommunication NetworksCopyright 2005 network Layer CCITT CCITT ISO Further Summary725. The Transport Transport network Transport Classes of Splitting and Flow Error Transport Layer Further Reading726. The Session Session Session Layer Functional Session Activities and Dialogue Error Reporting and Session Layer Further Reading837. The Presentation Presentation Service Functional Abstract Syntax Notation Definitions in Basic Encoding Presentation Presentation Further Reading948.

3 The Application Application Application Common Application Service Association Reliable Remote Specific Application Service Virtual Message Handling File Transfer, Access, and Other Further Reading1089. Local Area Basic Topologies and Access IEEE 802 Logical Link Token Token ANSI FDDI Token Ring Further Reading12010. Telephone Basic A Simple Networks Switching Subscriber Interexchange Signaling128xCommunication NetworksCopyright 2005 Common Channel Signaling System Number Signaling Data Signaling Link Signaling network Signaling Connection Control User Operations and Maintenance Applications Private Telephone PBX Corporate Intelligent Further Reading13911.

4 Integrated Services Digital Basic ISDN Functional Groupings and Reference ISDN Protocol The Physical The Data Link The network Frame Frame ISDN Further Reading15912. Broadband ISDN and Broadband B-ISDN B-ISDN User- network B-ISDN Protocol Asynchronous Transfer Channels and ATM Physical SDH-Based Cell-Based Cell HEC Generation and Cell Rate ATM Generic Flow Virtual Path Virtual Channel Payload Cell Loss ATM Adaptation Segmentation and Reassembly Convergence B-ISDN Further Reading175 Bibliography160xCommunication NetworksCopyright 2005 PragSoftPrefaceThis book is concerned with post-computer Communication Networks and two of itsimportant streams: data Communication and telecommunication.

5 Data communicationrefers to the Communication between digital computers, facilitated by computernetworks. Telecommunication refers to the primarily human-to-humancommunication facilitated by the global telephone system. The differences betweenthese two streams are mainly due to historical reasons. Telecommunication isincreasingly relying on digital computer technology, and data Communication is relyingmore than ever on telecommunication Networks . The two streams are to this field are often bewildered by the substantial wealth ofinformation already published on the subject.

6 This book is aimed at this group ofpeople. It provides a broad coverage of the key concepts, techniques, andterminology, so as to prepare readers for more advanced discussions. In-depthdiscussions of technically-involved topics are intentionally avoided in favor of moregeneral concepts. No previous knowledge of Networks or programming is structure of the book is as follows. chapter 1 introduces computer networksand explains some of their elementary concepts. It also introduces the OSI referencemodel, upon which later chapters are based. Each of Chapters 2-8 describes one ofthe seven layers of the OSI model in the context of wide area data 9 looks at local area Networks and their applications.

7 chapter 10 providesan introduction to telecommunication. chapter 11 builds on earlier chapters byexamining ISDN as the merging point of data and voice Networks . chapter 12 looksat the ATM technology and the potential applications that it can 1: computer network is the infrastructure that allows two or more computers (calledhosts) to communicate with each other. The network achieves this by providing a setof rules for Communication , called protocols, which should be observed by allparticipating hosts. The need for a protocol should be obvious: it allows differentcomputers from different vendors and with different operating characteristics to speak the same language.

8 This chapter introduces the fundamental concepts of computer Networks . Wewill first look at constituent network components and various network types, andthen describe a reference model for network protocol architectures which we willexpand upon throughout the rest of this book. We will also discuss the role ofinternational standards and major standards reading this chapter you should be able to: Describe the general characteristics of a computer network . Understand the role of the major components of a computer network . Distinguish between different network types and understand their properties.

9 Appreciate the relevance and importance of standards, in general, and the OSImodel, in particular. Describe the role and functions of each of the OSI layers. Use sequence and state transition diagrams to interpret and describe protocols. Appreciate the wealth of knowledge available on Communication NetworksCopyright 2005 ComponentsFigure shows an abstract view of a network and its hosts. The network is madeup of two types of components: nodes and Communication lines. The nodestypically handle the network protocols and provide switching capabilities. A node isusually itself a computer (general or special) which runs specific network Communication lines may take many different shapes and forms, even in thesame network .

10 Examples include: copper wire cables, optical fiber, radio channels,and telephone host is connected to the network by a separate Communication line whichconnects it to one of the nodes. In most cases, more than one host may beconnected to the same node. From a host s point of view, the entire network may beviewed as a black box, to which many other hosts are connected. Each host has aunique address allocated to it by the network . For a host to communicate withanother host, it needs to know the latter s address. All Communication between hostspasses through the nodes, which in turn determine how to route messages across thenetwork, from one point to abstract the rest of this book, there will be occasions when it is not necessaryto distinguish between hosts and nodes.