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Feature SummaryOrganization
The book is organized into four major sections: the first section provides the big picture; the second section develops fundamental concepts; the third section deals with advanced topics and detailed network architectures; two appendices provide important supporting material. I. Big Picture First: Networks, Services, and Layered Architectures
This section begins in Chapter 1 with a discussion of applications that the student is familiar with (World Wide Web, e-mail, telephone call) and that are based on networks. These examples are used to emphasize that modern networks must be designed to support a wide range of applications. We then discuss the evolution of telegraph, telephone, and computer networks, up to the present Internet to identify the essential functions that are common to all networks. This lays the groundwork for the discussion on layered architectures in the next section.
In Chapter 2 we develop the view of the network as a provider of services to applications and introduce the notion of a layered network architecture.
• We consider the e-mail and Web browsing applications, and we explain the application layer protocols that support these, namely HTTP, SMTP, and DNS. • We also explain how the application layer protocols in turn make use of the communication services provided by the Internet, namely TCP and UDP over IP. • Together the above examples motivate the notion of layering, leading naturally to a discussion of the OSI Reference Model. • Next we preview the Internet architecture and present a detailed example to show how Ethernet, PPP, IP, TCP and UDP work together to support the application layer protocols. The key notions of addressing and encapsulation are developed in this example. We use a network analyzer (packet sniffer) to examine the details of packet exchanges captured in the HTTP and e-mail examples. • The next section is optional and provides an introduction to sockets and network programming. Sockets and TCP/IP utilities provide the basis for very useful and practical exercises and experiments that provide students with “hands on” networking experience. • The final section provides an introduction to additional application layer protocols and to TCP/IP utilities such as ping and traceroute. We also introduce the public domain Ethereal network analyzer. The use of a network analyzer allows the student to analyze and experiment with real packet sequences in a home LAN or in a lab environment. We have found that the use of the network analyzer sparks interest in students for a material that otherwise appears abstract and remote. We provide suggestions for experiments and projects later in this section.
We believe that the student will be familiar with applications that are used in the examples, and so Chapter 2 can serve as a bridge to the less visible topics relating to the internal operation of a network. II. Fundamental Network Architecture Concepts
The second major section of the book develops the fundamental concepts of network architecture and protocols, proceeding from the physical layer to the network layer. We complement the discussion of fundamental concepts with sections that explore trends in network architecture.
Chapters 3 deals with digital transmission including error detection. This chapter contains more material than can be covered in the introductory course, so it is written to allow the instructor to pick and choose what sections to cover.
• In the first two sections we identify the bit rate requirements that applications impose on the network, and then we examine the transmission capabilities of existing and emerging networks. These two sections provide a minimum coverage of the physical layer and allow much of the remainder of the chapter to be skipped. • The next sections provide more detail on the physical layer. We introduce the relationship between bandwidth, bit rate, and signal-to-noise ratio, and then develop the basic digital transmission techniques, using modem standards as examples. • The properties of various media (copper wires, coaxial cable, radio, optical fiber) and their possible role in emerging access networks are then discussed. • The last section in the chapter introduces error detection and correction techniques. Some instructors prefer to combine this section with the chapter 5 section of ARQ.
Chapter 4 discusses digital multiplexing systems and circuit-switching networks.
• The first section introduces the digital multiplexing hierarchy that evolved around the telephone network. • The next two sections introduce the SONET multiplexing standard and explain how reliable transport ring networks are designed using SONET. • We then introduce wavelength division multiplexing and explain how WDM optical networks share the flexible network configuration features of SONET. • The next section presents an introduction to the design of circuit switches for traditional telephone networks and for emerging optical networks. • The next two sections deal with telephone networks, with a focus on the signaling system that enables telephone service and associated enhanced services, e.g. caller ID, 800-call. We consider the telephone network and the layered architecture of its signaling system. • Finally, we discuss the frequency reuse concept and its application in cellular radio networks.
The material in Chapter 4 is important to understand the physical infrastructure of modern networks. However, typically much of the material in Chapter 4 is not covered in an introductory networks course due to lack of time. Note: add that optional sections clearly marked.
Chapter 5 consists of two parts. The first part focuses on peer-to-peer protocols in general. The second part presents the data link control layer.
• We begin Part 1 with a discussion of peer-to-peer protocols and service models. We present examples that show how a protocol in one layer builds on the services of the layer below. • We use ARQ protocols (that provide reliable transfer service) to provide a detailed example of peer-to-peer protocols. The detailed discussion gives the student an appreciation of the issues in designing and implementing a communications protocol that operates between systems that are separated geographically. We also use ARQ to introduce the impact of delay-bandwidth product on the performance of protocols. • The end-to-end and hop-by-hop approaches to deploying peer-to-peer protocols are compared, and additional examples of peer-to-peer protocols are introduced for flow control and for timing recovery. We also preview the reliable stream service provided by TCP. • Part 2 begins with a discussion of framing techniques. • The Point-to-Point Protocol (PPP) is introduced next. • The next section introduces HDLC. • In the last section, we discuss the sharing of a data link by multiple packet flows and introduce the notion of multiplexing gain.
Chapter 6 consists of two parts. The first part deals with medium access control protocols. The second part deals with local area network protocols and standards.
• Part 1 begins with an introduction to broadcast networks and to random access and scheduling approaches to sharing a medium. • We introduce random access protocols and focus on Aloha and Slotted Aloha. • Reservation, polling, and token passing protocols are discussed next. The impact of delay-bandwidth product on the performance of these protocols is introduced. • We also discuss FDMA, TDMA, and CDMA channelization approaches to sharing media and we show their application in various existing cellular radio networks. • Part 1 ends with an optional section on performance modeling of medium access control protocols. • Part 2 begins with an explanation of the function of LANs and their placement in the OSI reference model. • The Ethernet LAN protocol is discussed in detail. We examine the impact of delay-bandwidth product on performance, and we show why this dictates the evolution of Ethernet from a shared medium access technique to a switched technique. • The next two sections, discuss token ring and FDDI LANs. • The emerging IEEE 802.11 wireless LAN standard is discussed in detail in the next section. • The final section introduces LAN bridges and explains virtual LANs and Ethernet switches.
Chapter 7 deals with packet switching networks.
• To provide a context for the chapter we begin by presenting an end-to-end view of packet transfer across the Internet. • We then develop the notions of datagram and virtual circuit packet switching, using IP and ATM as examples. We introduce basic design approaches to packet switches and routers. • Shortest path algorithms and the link state and distance vector approaches to selecting routes in a network are presented next. The importance of hierarchical addressing to network scalability is discussed. • ATM and the concept of label switching of packet flows are introduced next. • The final three sections are optional and introduce traffic management. Traffic management at the packet level discusses the relationship between Quality of Service and traffic shaping, scheduling and call admission control. Open loop and closed loop congestion control is discussed next. Finally traffic engineering of aggregated traffic flows is considered. III. Key Architectures and Advanced Topics
This major section shows how the fundamental networking concepts are embodied in two key network architectures, ATM and TCP/IP. The section also deals with the interworking of ATM and TCP/IP, as well as with enhancements to TCP/IP to provide secure and more responsive communications.
Chapter 8 presents a detailed discussion of TCP/IP protocols.
• We examine the structure of the IP layer and the details of IP addressing, routing, and fragmentation and reassembly. • We discuss the motivation and present the features of IPv6. • We introduce UDP, and examine in detail how TCP provides reliable stream service and flow control end-to-end across a connectionless packet network. • RIP, OSPF, and BGP are introduced as protocols for synthesizing routing tables in the Internet. Multicast routing is also introduced. • The final section introduces DHCP and Mobile IP.
Chapter 9 deals with the architecture of ATM networks.
• The ATM layer is explained, and Quality-of-Service and the ATM network service categories are presented. • The various types of ATM Adaptation Layer protocols are discussed next. • ATM signaling and PNNI routing are introduced.
Chapter 10 deals with advanced topics in network architectures and with proposed enhancements to IP.
• We introduce RSVP, Integrated Services IP, and Differentiated Services IP which together provide mechanisms for providing Quality of Service over IP. • We examine the overlay and peer models to interconnection of networks. • We then introduce multiprotocol label switching and discuss its role in traffic engineering and in virtual networks. We introduce generalized MPLS and explain its importance in simplifying the control and management of future networks. • The following section introduces the Real Time Transport protocol and explains its role in supporting multimedia applications over the Internet. • The final section discusses the Session Initiation Protocol and provides examples of how SIP can support the next generation of Internet services that can replace existing telephone-based services.
Chapter 11 provides an introduction to network security protocols.
• We first introduce the various categories of threats that can arise in a network are used to identify various types of security requirements that can be placed on network security protocols. Secret key and public key cryptography are introduced and their application to providing security is discussed. • We develop protocols that provide security across insecure networks and we introduce protocols for establishing security associations and for managing keys. These general protocols are then related to the IP security protocols and to transport layer security protocols. • We provide an introduction to the DES and RSA cryptographic algorithms .
Chapter 12 deals with the properties and compression of multimedia information. The material in this chapter complements the previous discussions of RTP and SIP.
• We begin with an Introduction to lossless data compression techniques. • We discuss predictive and subband techniques for achieving high compression of speech and audio signals. • We introduce the JPEG and MPEG image and video coding standards.
The book ends with an Epilogue that discusses trends in network architecture and identifies several areas that are likely to influence the development of future networks.IV. Appendices
Appendix A deals with network performance models. Network performance is an integral part of network design and operation. In the text we use quantitative examples to illustrate the tradeoffs involved in various situations. We believe that an intuition for performance issues can be developed without delving into the underlying mathematics. Delay and loss performance results are introduced in the sections that deal with multiplexing, trunking, and medium access control. In these sections, the dynamics of the given problem are described and the key performance results are presented. However the performance results are not developed in the text. The purpose of Appendix A is to develop the analysis of the performance models that are cited in the text. These analyses may be incorporated into more advanced courses on communication networks.
Appendix B provides an introduction to network management. The basic functions and structure of a network management system are introduced as well as the Simple Network Management Protocol (SNMP). We describe the rules for describing management information, and we also describe the collection of objects, called Management Information Base, that are managed by SNMP. We also introduce remote monitoring (RMON) that offers extensive network diagnostic, planning, and performance information. |
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2003 McGraw-Hill Higher Education