Transcription
Data Communication and Computer Network
Data Communication and Computer NetworkAbout the TutorialThis tutorial gives very good understanding on Data Communication and ComputerNetworks. After completing this tutorial, you will find yourself at a moderate levelof expertise in knowing DCN, from where you can take yourself to next levels.AudienceThis tutorial is prepared for the beginners to help them understand DataCommunication and Computer Networks.PrerequisitesBefore proceeding with this tutorial, you need a basic understanding of Computer.You should know the basics of input and output devices, primary and secondarymemory, and operating system.Disclaimer & Copyright Copyright 2014 by Tutorials Point (I) Pvt. Ltd.All the content and graphics published in this e-book are the property of TutorialsPoint (I) Pvt. Ltd. The user of this e-book is prohibited to reuse, retain, copy,distribute or republish any contents or a part of contents of this e-book in anymanner without written consent of the publisher. We strive to update the contentsof our website and tutorials as timely and as precisely as possible, however, thecontents may contain inaccuracies or errors. Tutorials Point (I) Pvt. Ltd. providesno guarantee regarding the accuracy, timeliness or completeness of our websiteor its contents including this tutorial. If you discover any errors on our website orin this tutorial, please notify us at contact@tutorialspoint.com.i
Data Communication and Computer NetworkContentsAbout the Tutorial . iAudience . iPrerequisites . iDisclaimer & Copyright . iContents . ii1. OVERVIEW . 1Classification of Computer Networks . 1Geographical Span . 1Inter-Connectivity . 1Administration . 2Network Architecture . 2Network Applications . 22. TYPES OF COMPUTER NETWORKS . 3Personal Area Network . 3Local Area Network. 3Metropolitan Area Network . 4Wide Area Network . 5Internetwork. 63. NETWORK LAN TECHNOLOGIES . 8Ethernet . 8Fast-Ethernet . 8Giga-Ethernet. 8Virtual LAN. 94. COMPUTER NETWORK TOPOLOGIES. 10Point-to-Point . 10Bus Topology . 10ii
Data Communication and Computer NetworkStar Topology . 11Ring Topology . 12Mesh Topology . 13Tree Topology . 14Daisy Chain . 15Hybrid Topology. 155. COMPUTER NETWORK MODEL . 17Layered Tasks. 17OSI Model . 18Internet Model . 196. COMPUTER NETWORK SECURITY . 20Secret Key Encryption . 21Public Key Encryption . 21Message Digest . 217. PHYSICAL LAYER INTRODUCTION . 22Signals. 22Transmission Impairment . 22Transmission Media . 23Channel Capacity . 23Multiplexing. 24Switching . 248. DIGITAL TRANSMISSION . 25Digital-to-Digital Conversion . 25Line Coding . 25Unipolar Encoding . 26Polar Encoding . 26Bipolar Encoding . 28iii
Data Communication and Computer NetworkBlock Coding . 28Analog-to-Digital Conversion . 29Sampling . 29Quantization . 29Encoding . 30Transmission Modes . 309. ANALOG TRANSMISSION. 32Digital-to-Analog Conversion . 32Analog-to-Analog Conversion . 3410. TRANSMISSION MEDIA. 38Magnetic Media . 38Twisted Pair Cable . 38Coaxial Cable . 39Power Lines . 40Fiber Optics . 4011. WIRELESS TRANSMISSION . 42Radio Transmission . 42Microwave Transmission . 43Infrared Transmission . 44Light Transmission . 4412. MULTIPLEXING . 46Frequency Division Multiplexing . 46Time Division Multiplexing . 46Wavelength Division Multiplexing . 47Code Division Multiplexing . 4813. SWITCHING . 49Circuit Switching . 49iv
Data Communication and Computer NetworkMessage Switching. 50Packet Switching . 5114. DATA LINK LAYER INTRODUCTION . 53Functionality of Data-link Layer . 5315. ERROR DETECTION AND CORRECTION . 55Types of Errors . 55Error Detection . 56Error Correction . 5716. DATA LINK CONTROL AND PROTOCOLS . 59Flow Control . 59Error Control . 6017. NETWORK LAYER INTRODUCTION. 64Layer-3 Functionalities . 64Network Layer Features . 6418. NETWORK ADDRESSING . 6519. NETWORK ROUTING . 67Unicast routing . 67Broadcast routing . 68Multicast Routing. 69Anycast Routing . 69Unicast Routing Protocols . 70Multicast Routing Protocols . 70Routing Algorithms . 7120. INTERNETWORKING . 72Tunneling . 72Packet Fragmentation . 73v
Data Communication and Computer Network21. NETWORK LAYER PROTOCOLS . 75Address Resolution Protocol (ARP) . 75Internet Control Message Protocol (ICMP) . 76Internet Protocol Version 4 (IPv4) . 76Internet Protocol Version 6 (IPv6) . 7722. TRANSPORT LAYER INTRODUCTION . 78Functions . 78End-to-End Communication . 7823. TRANSMISSION CONTROL PROTOCOL. 80Features . 80Header . 80Addressing . 82Connection Management. 82Bandwidth Management . 83Error Control and Flow Control . 84Multiplexing. 84Congestion Control . 84Timer Management . 85Crash Recovery . 8524. USER DATAGRAM PROTOCOL . 87Requirement of UDP . 87Features . 87UDP Header . 87UDP application . 8825. APPLICATION LAYER INTRODUCTION . 8926. CLIENT-SERVER MODEL. 91vi
Data Communication and Computer NetworkCommunication . 9227. APPLICATION PROTOCOLS . 94Domain Name System . 94Simple Mail Transfer Protocol . 94File Transfer Protocol . 94Post Office Protocol (POP) . 95Hyper Text Transfer Protocol (HTTP) . 9528. NETWORK SERVICES . 96Directory Services . 96File Services . 96Communication Services . 97Application Services . 97vii
Data Communication and Computer Network1. OVERVIEWA system of interconnected computers and computerized peripherals such as printersis called computer network. This interconnection among computers facilitatesinformation sharing among them. Computers may connect to each other by eitherwired or wireless media.Classification of Computer NetworksComputer networks are classified based on various factors. They include: Geographical span Inter-connectivity Administration ArchitectureGeographical SpanGeographically a network can be seen in one of the following categories: It may be spanned across your table, among Bluetooth enabled devices,Ranging not more than few meters. It may be spanned across a whole building, including intermediate devices toconnect all floors. It may be spanned across a whole city. It may be spanned across multiple cities or provinces. It may be one network covering whole world.Inter-ConnectivityComponents of a network can be connected to each other differently in some fashion.By connectedness we mean either logically, physically, or both ways. Every single device can be connected to every other device on network, makingthe network mesh. All devices can be connected to a single medium but geographicallydisconnected, created bus-like structure. Each device is connected to its left and right peers only, creating linearstructure.1
Data Communication and Computer Network All devices connected together with a single device, creating star-likestructure. All devices connected arbitrarily using all previous ways to connect each other,resulting in a hybrid structure.AdministrationFrom an administrator’s point of view, a network can be private network whichbelongs a single autonomous system and cannot be accessed outside its physical orlogical domain. A network can be public, which is accessed by all.Network ArchitectureComputer networks can be discriminated into various types such as Client-Server,peer-to-peer or hybrid, depending upon its architecture. There can be one or more systems acting as Server. Other being Client,requests the Server to serve requests. Server takes and processes request onbehalf of Clients. Two systems can be connected Point-to-Point, or in back-to-back fashion. Theyboth reside at the same level and called peers. There can be hybrid network which involves network architecture of both theabove types.Network ApplicationsComputer systems and peripherals are connected to form a network. They providenumerous advantages: Resource sharing such as printers and storage devices Exchange of information by means of e-Mails and FTP Information sharing by using Web or Internet Interaction with other users using dynamic web pages IP phones Video conferences Parallel computing Instant messaging2
Data Communication and Computer Network2. TYPES OF COMPUTER NETWORKSGenerally, networks are distinguished based on their geographical span. A networkcan be as small as distance between your mobile phone and its Bluetooth headphoneand as large as the internet itself, covering the whole geographical world.Personal Area NetworkA Personal Area Network (PAN) is smallest network which is very personal to a user.This may include Bluetooth enabled devices or infra-red enabled devices. PAN hasconnectivity range up to 10 meters. PAN may include wireless computer keyboardand mouse, Bluetooth enabled headphones, wireless printers, and TV remotes.For example, Piconet is Bluetooth-enabled Personal Area Network which may containup to 8 devices connected together in a master-slave fashion.Local Area NetworkA computer network spanned inside a building and operated under singleadministrative system is generally termed as Local Area Network (LAN). Usually, LANcovers an organization offices, schools, colleges or universities. Number of systemsconnected in LAN may vary from as least as two to as much as 16 million.3
Data Communication and Computer NetworkLAN provides a useful way of sharing the resources between end users. The resourcessuch as printers, file servers, scanners, and internet are easily sharable amongcomputers.LANs are composed of inexpensive networking and routing equipment. It maycontains local servers serving file storage and other locally shared applications. Itmostly operates on private IP addresses and does not involve heavy routing. LANworks under its own local domain and controlled centrally.LAN uses either Ethernet or Token-ring technology. Ethernet is most widely employedLAN technology and uses Star topology, while Token-ring is rarely seen.LAN can be wired, wireless, or in both forms at once.Metropolitan Area NetworkThe Metropolitan Area Network (MAN) generally expands throughout a city such ascable TV network. It can be in the form of Ethernet, Token-ring, ATM, or FiberDistributed Data Interface (FDDI).Metro Ethernet is a service which is provided by ISPs. This service enables its usersto expand their Local Area Networks. For example, MAN can help an organization toconnect all of its offices in a city.4
Data Communication and Computer NetworkBackbone of MAN is high-capacity and high-speed fiber optics. MAN works in betweenLocal Area Network and Wide Area Network. MAN provides uplink for LANs to WANsor internet.Wide Area NetworkAs the name suggests, the Wide Area Network (WAN) covers a wide area which mayspan across provinces and even a whole country. Generally, telecommunicationnetworks are Wide Area Network. These networks provide connectivity to MANs andLANs. Since they are equipped with very high speed backbone, WANs use veryexpensive network equipment.5
Data Communication and Computer NetworkWAN may use advanced technologies such as Asynchronous Transfer Mode (ATM),Frame Relay, and Synchronous Optical Network (SONET). WAN may be managed bymultiple administration.InternetworkA network of networks is called an internetwork, or simply the internet. It is thelargest network in existence on this planet. The internet hugely connects all WANsand it can have connection to LANs and Home networks. Internet uses TCP/IPprotocol suite and uses IP as its addressing protocol. Present day, Internet is widelyimplemented using IPv4. Because of shortage of address spaces, it is graduallymigrating from IPv4 to IPv6.Internet enables its users to share and access enormous amount of informationworldwide. It uses WWW, FTP, email services, audio, and video streaming etc. Athuge level, internet works on Client-Server model.Internet uses very high speed backbone of fiber optics. To inter-connect variouscontinents, fibers are laid under sea known to us as submarine communication cable.Internet is widely deployed on World Wide Web services using HTML linked pagesand is accessible by client software known as Web Browsers. When a user requestsa page using some web browser located on some Web Server anywhere in the world,the Web Server responds with the proper HTML page. The communication delay isvery low.Internet is serving many proposes and is involved in many aspects of life. Some ofthem are:6
Data Communication and Computer Network Web sites E-mail Instant Messaging Blogging Social Media Marketing Networking Resource Shari
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