BIT en are 3 EDITION : 2020 2 TEAUMINALSUBJECT CODE : 29414 As per Revised Syllabus of MSBTE - I SCHEME SLY. Diploma Semester - IV Computer Engineering Group (CO/CM/IF/ OW) DATA COMMUNICATION & COMPUTER NETWORK Vilos 8. Bagad Iresh A. Dhotre ME. (Information Technology] txFoculy, Sinhgod College of Eraineering, Pune Virot V. Giri MTech, (Computer Ergo) Sanjay Ghodowat Polytechnic Atgore, Kolhapur Sachin S$. Mahulkar JSPAY's Jayamontrae Sawant Polytechnic, Hadapor, Pure = TECHNICAL | PUBLICATIONS < nen Up-Thrust for Knowleée0DATA COMMUNICATION & COMPUTER NETWORK Subject Code : 29414 S.¥. Diploma Semester - IV ‘Computer Engineering Group (CO / CM/ IF / CW) First Edition : January 2019 Second Revised Edition : January 2020 © Copyright with Authors All publizhing rights (printed and ebook version) reserved with Technical Publications. No per! ofthis book should be reproduced in any form, Electronic, Mechanical, Photocopy or any information storage and retrieval system without prior permission in writing, from Technical Publications, Pune. Published by GAL Ari Rodency Office No, 412, Shrinr Rol, Pune «41109 '20-24495496/07, Telefax: +91 -020 ‘dan nceteciteshons org Wabule:soncieuiedositatoreog Ls Printer Yosia|Pnten & Brdes SNe. 10/1 {Ghul Industral Estate, Nerd Vilage Ros, Tah Hoel, Dt Pane 411081 rice : € 124 ISBN 332-0058-8 Arges3sl00s 85 9799333900585 [2] ” MSBTEPREFACE The importance of Data Communication and Computer Network is well known in various engineering fields. Overwhelming response to our books on various subjects inspired us to write this book. The book is structured to cover the Rey aspects of the subject Data Communication and Computer Network. The book uses plain, lucid language to explain fundamentals of this subject. The book provides logical method of explaining various complicated concepts and stepwise methods to explain the important topics. Each chapter is well supported with necessary. illustrations, practical examples and solved problems. All chapters in this book are arranged in @ proper sequence that permits each topic to build upon earlier studies. All care has been taken to make students comfortable in understanding the basic concepts of this subject Representative questions have been added at the end of each section to help the students in picking important points from that section. The book not only covers the entire scope of the subject but explains the philosophy of the subject. This makes the understanding of this subject more clear and makes it more imeresting. The book will be very useful not only to the students but also to the subject teachers, The students have to omit nothing and possibly have to cover nothing more We wish 10 express our profound thanks to all those who helped in making this book a reality. Much needed moral support end encouregement is provided on numerous occasions by our whole family. We wish to thank the Publisher and the entire team of Technical Publications who have taken immense pain to get this book in time with quality printing Any suggestion for the Improvement of the book will be acknowledged and weil appreciated Authors D.S. Bagad D.A. Dhotre Dinat V. Girt Sachin 3, Mahathar Dedicated to GodSYLLABUS Data Communication and Computer Network (22414) Examination Schome LT ]P| creat heen) racial (+19) [paper |_ 65 PA Total ESE PA Tota cs | wax [win] wax] wn | wax | min | wax | mn | max] win | wax | win seh «© [os [ie [es for [oo [100 [0 [ase [0 [as | [0 | 2 Unit Unit Outcomes (UO) “Topics and Subtopics {an cognitive domain) Uat-1 [te Describe role of the given [11 Process of dat communication ands component i the process of | components" Transmitter, Receiver, Fundamentals of | Gatcommunicstion Mediums, Message, Protocol Comes ation 1b: Compare the characterise |12 Protocols, Slardards, Standard — of analog and digtal signals |" crganizations. Bandwidth,” Data ind Coapsiet fon the given parameter Teancmission Rate, Bad Rate and Bits per 1c. Explain the process of data | Sond. communication using the ]1.9 Modes of communication (Simplex, Half given mode Duplex, Full Duples). 1d. Classify computer networks | 14 Analog Signal and Digital Signal, Anlog on the specified parameter, and Digital Transmission: Analog t0 Je. Select network architecture | Digital, Digital to Analog Conversion for the given situation with | 15 Fundamental of Computer Network justlication Definition and Need of Computer Network, Applications, Network Benefits 16 feation of Network : LAN, WAN, 17 Network Architecture : Peet to Peet, Client Server Network Unit-1 [20 Explain with sketches the [21 Communication Media Guided 1 constrtction of given type of | ‘Transmission. Media Twisted - Pair Cable, eerie cable Coaxial Cable Fiber ~ Optic Cable Wein: [2b Explain with sketches the |22 Unguided Transmission Media Radio Sas characteristics of the given | Waves, Microwaves, infrared, Satelit type of unguided | 95 Line - of - sight Transmission Point to tansimission media Point, Brondeasting 2c. Explain with sketches the |» 4 Teequency: x. Tiillee working of the Multiplexing Time = Division Multiplexing pcan 5 Switching : Circuit ~ switehed networks, working. ‘principle of the given sivitehing fechnigue 2e. Compare different switching techniques on” the givet parameter, i»Uaki-ai [3a Esplin working _of the] 81 Types of Grsom «Single Bit Envor and Barat Fr eesga, | sien error detection and |". Exfor, Redundancy anierse correction method. 2.2. Exvor Detection ; Longitudinal Redundancy rection 24 |, Explain features ofthe given | ~ Check (URC), Verio Redundancy "Check i , eke Communisiton | (WRG), Cyehc ‘Redundancy. check (CRC) ommunication ‘standard. Forward 3.3. Error Correction : Forward 3c. Explain characteristics of the ‘error Correction, gion Layer in LEE 80211 [33 IEEE standards + 802.1, 9022, 8023, 8024, Srehtectare 02s, da, Compare the specified | 4 Wireless LANs : $02.11 Architecture, MAC generations of “Tmobile| ~ Sublayer, Addressing Mechanism elephone system on the | 5.5 Bluetooth Architecture ; Piconet, Scatternet GN Pea 3.6 Mobile Generations : 1G, 2G, 3G, 4G and 3e. Explain with sketches the |*° 50? Be RG A SS oets of creating Bluetooth architecture. Uitte revang stork | 47 Nework Topologies - nition : topology “for the” given| Delintion, Selectan, Criteria "Types of Network stuaticn Topology : i) Bus i) Ring i) Star) Mesh Topaesies and | 4S ‘ Fire hes 3 Network Devices | 4 Compare itirest topologies on the given | 4.2 Network Connecting Devices : Hub, parameter. Svriteh, Router, Repeater, Bridge, Gateway, tc fetect newwork connecting | Moder "Wists" tneatractare device for the given ‘components. Salon 44, Desenbe with skeiches. the procedure’ to configure the Elven networking device. | Unit-v [Sa Identity functions and|S1 Sl Reterence Model Layered Pia features of the given layer of| "Architecture eer ~ to = Peer Processes = etre O31 Reference model interfaces between layer, | Protocols, Models 5b. Compare the specific Organization of the Layers, Encapsulation Compare | the | specified | Livers ofthe OSI” Reference” Model Danette ® (Ganctions and features of each Layer) - Piyaieal Layer, Dat = Link Layer, Network Se. Classify IP addresses on the Layer, Transport Layer, Season Layer, basis of i class from the Presentation Layer, Application Layer. a oe 5.2. TCP/IP Model : Layered Architecture, Data 5d. Distinguish between [Pvd Link Layer : Nodes and links, services, two and TPv6 on the given categories of links, two sub layers, Link parameters lapel aldresing: thee types of addresses, Ba Desccile: with itching ha address resolution protocol. (ARP), Network Layer: Addressis: address space ven TCP/IP service Clssfal and classless addressing, dynamic fost “configuration “protocol” (DHCP), network dress’ ecluton (NAT) TTeanaport liver protocol Transpart layer services, connectionless and connection oriented protocol 53 Introduction = Addressing mechanism in the internet iP Addressing = Ht Address asses, closless IP addsessing, Sub superneting, Masking 54 IPvd and IPv6 55 _OSI and TCP/IP Network ModelLY TABLE OF CONTENTS Chapter-1 Fundamentals of Data Communication and Computer Network (1-4) to (1 - 14) 1.1 Dats Communication and tts Components. ret 1.1.1 Characterities ia 1.1.2 Components en 1.2 Protocols and Standards 1.2.1 Protocols ‘Communication Standards 1.22.1 Standard Organization 1.2.2.2 Intemet Standards 13 1.23. Channel Capacity, Bandwidth, Baud Rate, Bit Rate 1-3 1.3 Modes of Communication 1-3 1.3.1 Data Representation 13 1.3.2 Data Flow 1a 1.32.1 Simplex bea 1.32.2 Half Duples. 14 1.3.2.3 Full-Duplex 14 1.4 Analog and Digital Sign: 1-5 1.4.1 Comparison of Analog and Digital Signal 1-6 1.42 Periodie and Non-periodic Signals 1-6 1.4.3 Comparison of Periodic and Non-periodie Signal 1-6 5 Analog and Digital Transmission Methods rey Analog versus Digital Transmission 1-8 1.5.2 Advantages and Disadvantages of Digital Signal 1-8 1.6 Fundamentals of Computer Network 1-8 1.6.1 Node 1-8 1.6.2 Branch 1-9 1.6.3 Goals at Computer Network 1 1.64 Benefits of Computer Network .- 1-9 1.6.$ Need of Neworking. 1-9 1.7 Classification of Network : LAN, MAN, WAN . 1 - 10 1.7.1 Local Area Network (LAN) 0 1.7.2 Metropolitan Area Networks (MAN), un wo Wide Area Networks (WAN). 1 1.7.4 Comparison between LAN, WAN and MAN 18 Network Architect 8.1 Peer-to-Peer Model 1.82 Clicnt-Scrver Model 1,9 Two Marks Questions with Answers Uni 0 Chapter-2 Transmission Media and ‘Switching (2-1) to (2 - 20) 2.1 Guided Transmission Media. 2-1 DAL Twisted Pair t 2.1.1.1 LinshieLded Twisted Pair UTP) Cable a 2.1.1.2 Shielded Twisted Pair (STP) Cable 2.1.1.3 Comparison of UTP and STP 2 Coaxial Cable 2 2.1.2.1 Baseband and Broadband Coanial Cable 2.1.3 Fiber Optic Cable 3 213.1 Types of Fiber as 21.3.2 Modes of Fier a4 21.2.3 Fiber Optic Configuration as 2.34 Characterstis of Fibre Opie Cable. 2-5 2.1.3.5 Advantages and Disadvantages of Optical Fiber 2- 2.14 Comparison between Coaxial, TP and FOC 2:6 2.2 Unguided Transmission Media, 2-6 2.21 Radio Wave 2-7 Microwave 2-7 223 Infrared. 2.9 4. Satellite Communication 2.3 Multiplexing, 23.1 Concept of Multiplexing 3.2. Frequency - Division Multi 23.3. Time Division Multiplexing (TDM) .... 224 Switching 2.4.1 Concepts of Citeuit Switching 2.4.2 Packet Switching 242.1 Datagram Packet Switching 2-16 242.2 Virtual Circuit Packet Switching. .. 2-16 2.4.2.3 Comparison of Virwal Circuit and Datzgrar. 2-17 243° Message Switching 2-17 Compazison of Cineuit, Packet and Message Switchin 2-18 2.5 Two Marks Questions with Answ -19 Chapter -3 Error Detection, Correction and Wireless Communication (31) to (3-36) 341 Error Control and Coding 3-1 3-1 2 3.1.1 Types of Errors 3.2 Envor Detecting 3.2.1 Redundancy . 3.2.2 Detection versus Corre 3-2 2.3 Forward Error Correction versus Retransmi 3.3 Block Coding 33.1 Entor Detection 3.3.2 Enor Conection 3.3.3 Hamming Distance. 3d Linear Block Codes 3.4 Parity Check, 3.4.2 Two Dimensional Parity Cheek 3-6 3-9 3.5.1 Cyclic Redundancy Check (CRC) 3-9 3.5.2 Polynomials -10 3.53 Degree of Polynomial 3-10 3.54 Cyclic Code Analysis, 3-10 3.5.5 Advantages of Cyclic Codes ul 3.6 IEEE Standards 3-13 3.6.1 IBEE 802.3 Ethernet 3-14 26 1.1 Ethernet Properties 3.14 3.6.1.2 [EEE 802.3 Frame Format 3-15 3.62 IEEE 802.4 Token Bus, -18 TECHNICAL PUBLICATIONS 3.6.2.1 IEEE 802.4 Fraime Format. 3-16 3.63 IEEE 802.5 Token Ring 3-17 3.63.1 Token Ring Frame Format 3.17 4.64 Comparison between IEEE 802.3, 802.4 and 8025 3-18 3.7 Wireless LANs 802.11 3-19 3.7.1 Architecture of 802.11 3-19 3.7.2 MAC Sublayer cal Layer 3.75 CSMACA 3.7.6 Difference between 802.114 and 802.11b . 3 3.48 Bluetooth, 3.8.1 Bluetooth Architecture: Piconet, Seat 3.8.2 Radio Laver 3.8.3 Baseband Layer 3.84 Frame Format 3.9 Mobile Gi erations 3-32 3.10 Two Marks Questions with Answers 3-34 Chapter -4 Network Topologies and Network Devices (4-1) to (4-18) 4.1 Network Topologies 4-1 4.1.1 Bus Topology. 4-1 4.1.2 Star Topology 4-1 4.1.3 Ring Topology 4-2 4.1.4 Mesh Topology 4-3 4.1.5 Comparison between Bus and Ring Topology 43 4.1.6 Hybrid Topology 4-4 4.2 Network Connecting Devices. 4.5 4.2.1 Hubs... 4s 4.2.1.1 Passive Hubs 4-5 4.2.1.2 Active Hubs 46 4.2.13 Intelligent Hubs 4-6 422 Switch 4-6 4.2.2.1 Layer2 Switch, 4-6 An pte fringe(va 4.2.22 Layer 3 Switch 4-6 42.2.3 Layer 4 Switch 4-6 4.2.24 Ditfecence between Hub and Ssiteh. 4-7 42.3 Repeater 4-7 424 Bridge 4-8 4.24, Bridge Arehitectre an 424.2 Functions of Bridges 4-8 4.24.3 Fixed Rating Bridges. 4.9 4244 Transparent Spanning Tive Bridges . 4-9 4.24.5 Source Routing Bridges atl 4.24.6 Remote Bridges 4-2 42.4.7 Comps Ro ‘son of Transparent and Soaree ing Bridge 4-12 42.48 Difference between Bridge and Repeater 4-12 42.5 Gateway. 4-3 42.6 Router 4.13 4.2.7 Difference between Various Network Connecting Device ans 42.8 Modem 4d 4.2.8.1 Need of Modern, 4e14 4.2.8.2 Block diagram and Working of Modem, 4-14 43 Wireless Inftastructure Components 4-16 44 Two Marks Questions with Answers 4 Chapter-5 Reference Models (5-1) to (5 - 32) 1 OSI Reference Model... 5-1 5.1.1 Layered Architect 5.1.2 Peer to Peer Processes 5.1.3 Layers in OSI Medel 5.1.3.1 Physical Layer 5.1.3.2 Data Link Layer 5.1.3.3 Network Layer 5.134 Transport Layer 4 5.1.3.5 Session Layer. 5-4 5.1.3.6 Presentation Layer 5 5.1.37 Application Layer 55 5.2 TCPIP Model 5-6 5.2.1 Comparison of the OSI and TCPIP Protocol Suite 5 5.2.2 Addressing 5-8 $3 Data Link Layer (DLL) 5-9 A Address Mapping ........ 5-10 54.1 Address Resolution Protocol (ARP) ..... $= 10 5.4.1 Packet Format SA.2 Reverse Address Resolution Protocol (RARP) 5-12 3-13 5 IP Addressing Scheme s-14 55.1 Addressing 3-14 55.2.Cha Addressing 5.8.3 Special IP Addresses 5.5.4 Network Address 5.8.5 Default Subnet Mask 5.5.6 Subnetting 5.5.7 Supernetti 5.5.8 Network Address 5.6 1PVG, 5.6.1 IPv6 Addresses. 5.6.2 IPv6 Packet and Header Format. 5.63 Comparison between IPV4 and IPV6 8.7 Dynamic Host Configuration Protocol (DHCP). 5.7.1 DHCP Message Format 8.8 Transport Layer 5.8.1 Addressing Method Translation (NAT) 5.8.2 Transport Layer Services, 5.9 ARP 5.10 Two Marks Questions with Answers ‘Solved Model Question Paper (M - 1) to (M-2) ¥ TECHIVCAL PUELEATIONS™- Anup must orinewea9eUNIT - I Fundamentals of Data Communication and Computer Network 14 Data Communication and Its Components co 10, Nar 4 Data communication means the exchange of data between two devices via some form of transmission medium. 4.1.1 | Characteristics 1. Delivery : Data must deliver to the correct destination. 2. Accuracy + Data must deliver accurately by the system. 3. Timeliness : The communication system must deliver data in a timely manner. 4, Jitter : Tt is a variation in the packet arrival time. 4.1.2 | Components +A data communication system consists of five components, 1) Message 2) Sender 5) Receiver 4) Medium 5) Protocol Fig. LL.1 shows components of data communication system. 1. Message +The message is data or information to be communicated. It can be text, numbers, pictures or sound Protocal ‘Sender ‘Wedum of Faraniscion 2. Sender * The sender is device that sends data, Various devices can be used to send the data 3. Receiver +The receiver receives the information/message transmitted by sendor 4. Medium et is a physical path through which message passes from sender to receiver. The transmission medium can be twisted-pair cable, co-axial cable, fiber-optic cable or radiowaves. 5. Protocol Protocol is a set of rules that governs data ‘communications. Protocol is a predecided terms for communication Board Questions 1. What is dato consnenication ? CEE 2. Drew the components of data connunication system and state the function of each component (ETRE) 3. Draw a sketch of shicided twisted pair cable and describe any two characteristics IMSBTE « Summer 47, Marka 4 Protocol Message Roceiver Fig, 4.1.1 Data communication componentsa oy ata Communication and Computer Network 1.2 | Protocols and Standards CSSA TALE 1.2.1 | Protocols «Protocols are the cules that govem network ‘communication, «Protocols are the rules that both the sender and receiver and all intermediate devices need to follow and able to communicate effectively. +A. protocol is a set of rules that governs data communications, Protocol defines the method of communication, how to communicate, when to communicate ete. Important elements of protocol are, 1 Syntax 2. Semantics 3. Timing. 4. Syntax + Syntax means format of data or the structure how it is prosented e.g. first eight bits are for sender address, next eight bits for receiver address and rest of the bits for message data, 2. Semantics = Semantics is the meaning of each section of bits eg. the the transmission or final destination of the message, address bit means route of 3. Timing + Timing means, at what me data can be sent and how fast data can be sont 122 + Standards provide guidelines to the manufacturers, venders, government agencies and service provider. It ensures the interconnectivity and compatibility of the device. +Standards help in maintaining competitiveness and guarantees interoperability Communication Standards market «Data communication standards are of two categories a) De facto : De facto means by facts or by convention, The standards that are not approved, by any organization but are widely used are De facto These are established by ‘manufacturers. standards, Fundamental of Data Communication and Computer Network b) De jure : regulation, recognized officially by an organization. De jure means by law or by Those are the standards that are ‘Standard Organization + Standards creation, are developed jointly by standard committees, forums and government regulatory agencies, Some standard organizations 1.180 4, ANSI 2. 1U-T 5. TIA 3. IEEE 1. International Standards Organization (180) + International standards produced and publisted by ISO, a voluntary —nontreaty organization founded in 1946, Its members are the national standards organizations of the 89 member counities. The 150 creates the sels of rules and stanclards for geaphies and document exchange and provide models for equipment and system compatibility, quality enhancement, productivity and reduced costs improved 2, International Telecommunications Union-Telecommunications Sector (ITU-T) + Membership in the ITU-T consists of government authorities and representatives TTU-T’s task is to make technical recommendations about telephone, telegraph and data communication interfaces, The ITU-T has developed three set of specifications from many ‘countries. LV series for modem interfacing and data transmission over telephone lines. 2. X series for data transmission over public digital network, e-mail and directory services. 3. | and Q series for ISDN and Broadband ISDN. its extension The real work of ITU-T is done in its 14 study groups, There are currently 14 study groups, covering topics ranging from telephone billing to multimedia 3, Institute of Electrical and Electronics Engineers + IEEE is an international professional organization founded in the US and is comprised of electronics, $ TEGHGAL PUELEATCNS"- An pit or mownese[Data Coninunication and Computer Network a computer and communications engineers. IEEE is the largest professional organization in the world. In addition to publishing scores of journals and running hundreds of conferences each year, IEEE group develops standards in the area of the electrical engineering. has a standardization that and computing, 4, American National Standards Institute ANSI + ANSI is a private, organization. Its common carriers, parties ANSI federal government of the US, it serves as the national co-ordinating standardization in the US, nongovernmental, nonprofit members are manufacturers, and other interested affiliations with the has no institution for voluntary 5. Telecommunication Industry Association +The TIA represents communications and manufacturers of information technology products and services provides for the global markeiplace through its core competencies, 1.222] Internet Standards ‘eIntemet stanclard set some rules which must be followed by all. There is strict procedure by which a specification attains Intemet standard status. ‘= Intemet draft is working documents. ‘Alter recommendation from the Internet authorities, 2 draft may be published Request For ‘Comment (RFC), + RFC is made available to all users. 4.2.3 | Channel Capacity, Bandwidth, Baud Rate, Bit Rate 41, Channel Capacity +The channel capacity is also called ay Shannon capacity. The channel capacity does not depend upon the signal levels used to represent the data. + An The maximum data rate for any noisy channel is ideal noiseless channel never exists TECOMICAL PUBLICATIONS Fundamentals of Data Contmunisstion and Computer Network where, © = Channel capacity in bits per second BW = Bandwidth of channel s N 7 Signal-to-Noise ratio. 2. Digital Bandwidth + Digital bandwidth is the maximum bit rate that 3 ‘medium can propagate through it. # The digital bandwith of a medium is expressed in bits per second (ops! 3. Baud rate + Baud indicates the rate at which a signal level ‘changes over a period of time. 4. Bit Rate + Bit rate is defined as the number of bit intervals per second. Bit rate is expressed in bils per second (ps). Board Questions 1, Define protocol. 2. Define the term baud rate. 3. Define connnitics 4. Define. protocol standards and list standard CEA What are the key elements of oeco!? CEA 5 Dyfine standards. List various stander erganizations. 6. List various standard organisation for data 4.3 | Modes of Communication 134 Data Representation + Data is represented in diferent types L. Text : Text is represented as a bit pattem, a sequence of bits ic. 0 or 1. ASCII code is used. 2, Numbers : Numbers are also represented by bit patterns. ASCII is not used for numbers An up thst forkaowidge+ 70% ‘Data Communication and Computer Newor fe ‘Fundamentals of Data Communication aed Computer Network 3. Images: Images are also represents by bit pattems. Image is composed of a matrix of pixels, 4. Audio : Audio is different from text, numbers and images. Audio is refers to the recording or broadcasting of sound or music. It is continuous, not discrete. 5, Video : It refers to the recording or broadcasting of a picture or movie. 4.3.2 | Data Flow + Communication between two devices ie. sender and receiver can be of three types 1, Simplex 2. Half-Duplex 3, Full-Duplex. 1321] Simpiox In simplex mode of communication, gpyy data can flow in one direction only Montor (unidirectional). One devices can Direction of gta transmit data and other device accepts the data and works accordingly. Fig, 1.3.1 shows simplex ‘communication mode, Fig. 1.3.4 Simplex communication + Typical example of simplex communication is a computer system, deta from flow from CPU to monitor or from keyboard to monitor in one direction only. 4322] Halt-Dupiex ‘+ In halfdupiex mode of communication each station can transmit or receive the message (data) Fig. 1.32 shows half-duplex communication mode, + An important condition in half-dupley mode is that both devices can not transmit at a time. The entire channel capacity is used by any device transmitting at that time. =m 5 =e | 4 Workstation -1 Work station - 2 Fig. 1.32 Half-duplex communication 3.2.3) FullDuplex +In fall-duplex mode, both stations can transmit and receive simultaneously. Fig. 13.3. shows full-duplex mocie of communication. + In full-duplex mode of communication, data flow in both directions share the channel capacity. A ‘common example of full-duplex communication is telephone network. Subscriber at both ends can talk and listen at the same time, Data flow \ ' }—_ oa — = Fig. 1.3.3 Fullduplex communication $ TECAMICAL PUBLICATIONS” Anup thst frkrowedaeSd 4.4] Analog and Digital Signals + Both data and the signals that \gigg represent them can be either analog or digital in form. Analog data refers to information that is continuous; digital data refers to — as information that has discrete states, T «The sine wave is the most fundamental form of a periodic analog signal. Fig. 14.1 shows a sine 144 Sine wave wave. Value « Digital data take on discrete values, All binary signals are digital, but all digital signals are not necessarily binary. Fig. 142 shows a binary digital signal, Tim Fig 143 shows analog ‘communication system, Fig, 1.4.2 Binary digital signal Digital output Analog ‘Analog source input Physical racy estinaton ) out Fig. 1.43 Analog communication systems ‘+ Converting information signals to a different form is called modulation, and the reverse process is called demodulation. The modulation signal is the information and the signal being modulated is called the eactier. Fig. 1.44 shows digital communication system | Distal Digital Digial = ) aie terminal terminal output Interface Intorfaco ‘rales AD pA | Arava \ input | Somer comets Tout ) Fig. 1.44 Digital communication system TECHNICAL PUBLICATIONS” Ax ptr nowData Communication and Computer Network Fundamentals of Data Communication an Computer Network 4.4.1 | Comparison of Analog and Digital Signal Sr. No. Analog signal Digital signal 1 ‘Analog signal is a continuous signal which Digital signals are discrete time signals generated by digital represents physical measurements modulation, Denoied by sine waves Denoted by square waves 3. Analog signal processing can be done in real time ‘There is no guarantee that digital signal processing can be and consumes less bandwidth, done in real time and consumes more bandwidth to carry out the same information. Stored in the form of wave signal. Stored in the form of binary bit. Subjected to deterioration by noise during Can be noise-immune without deterioration during teansmission and writejread cycle transmission and writejread cycle. Analog instrument draws large power Digital instrument draws only negligible power 7 Examples : Human voice in air, analog electronic Examples | Computers, CDs, DVDs, and other digital devices. electronic devices 1.4.2 | Periodic and Non-periodic Signals Periodic Signals : +A signal is periodic signal if it completes a pattern within a measurable time frame. A periodic signal is characterized by amplitude, frequency and phase. Mathematically a single frequency voltage waveform is vit) = V sin (pit +a) where v(t) = Time varying voltage sine wave V = Peak amplitude (wots) Frequency (hertz) Time (econds) Phase (degrees or radians) Non-periadie Signals : + Non-periodic signals ate also called as aperiodic signal. A non-periodic signal never repeats. It does not satisfy the periodicity property. + Both analog and digital signals can be periodic or non-periodic. But in data communications, periodic signals are analog signals and non-periodic signals are digital signals. 4.4.3 | Comparison of Periodic and Non-periodic Signal Sr. No. Periodic signal Aperiodie signal 1 A signal which repeats itself after a specific A signal which does not rpent itself after a specific interval Interval of time is called periodic signal. of time is called aperiodic signal A signal that repeats its pattern over a period is A signal that does not repeats its pattern over a period is called periodic signal ‘called aperiodic signal or non periodic. - TECHNICAL PUBLICATIONS”. A ue ctor inowado=ata Communication aad Computer Network Fundanientals of Data Comauunkaton and Comper Network 3 They can be represented by a mathematical equation. 4 Their value can be deiermined at any point of time. 5 They are doterminiatic signal 6 Example : Sine, cosine, square, sevrtoath ete ‘They cannot be represented by any mathematical equation, ‘Their value cannot be determined with certs given point of time. ‘They ore random signals, Example : Sound signals from radio, all types of noise ty at any signals. xt) ~) [Non-perioi signal {ES ESS r SALEBY ST SE, 7 Board Questions 1, State the following terms a) Amplitude b) Frequency o) Time period a) Phase CALE Differentiate between analog and digital signal Compare avalog signal and digital signal State the meaning i) Phase ii) Frequency tii) Bandwidth i) Tine poriod CTE 1.5 | Analog and Digital Transmission Methods + Digital means discrete form. The data in communication can be represented in digital form Le. in 0 and 1 form, + Since digital signals are usually not periodic in nature different terminology is used for representing, digital data, 1. Bit interval 2 Bit interval is the time required to send one single bit Bit rate : Bit rate is defined as the number of bit intervals per second, Bit rate is expressed in bits per second (bps) Vollage + Fig. 15.1 shows concept of bit interval and bit rate. Tine Digital bandwidth: Digital bandwidth is the maximum bit rate that 2 medium propagate through it. The digital bandwidth of 4 medlium is expressed in bits per second (bps). Frequency spectrum : Frequency spectrum is used to analyze and synthesize a signal. Frequency spectrum is the representation of signal in frequency domain. Frequency spectrum representation of amplitude and phase spectrum of signal TECHNICAL PUBLICATIOUS”. An wp hr or inoue[Daa Communication and Computer Network, 5. Baud rate signal level changes over a period of time. Baud indicates the rate at which a 11.5.1 | Analog versus Digital Transmission St. No. Analog transmission Digital transmission 1. Analog transmission Digital transmission. rnseds narrower needs bandwidth bandwidth, ‘between 0 and infinity. 2 Analog signal Digital signal ‘transmission requires a transmission requires bandpass channel “Lows poss channel 3. The bandwidth of a. Dedicated ‘medium can be divided Point-to-poiat or shared) into several bandpass medium in time among, channels to carry the devices. several analog eg. Wired LAN, a transmission. cable can be shared eg. In analog cellular between stations, telephony a limited BW divided into number of 4.5.2 | Advantages and Disadvantages of Digital nal Advantages 1. Analog circuits require amplifiers and each amplifier adds distortion and noise to the signal 2 In contrast, digital amplifiers regenerate an exact signal, eliminating cumulative errors 3. Voice, data, video, ete. can all by carried by digital circuits 4. Digital signals can be compressed so more channels can be transmitted along the same, 5. Can connect several different users to the same link - such as video conferencing, Fundamentals of Data Communication and Computer Netvook Disadvantages 1. Digital signals need more ‘bandwidth to transmit the same. 2. The transmitter and receiver have to synchronize very carefully 30 that the information makes 1.6 | Fundamentals of Computer Network cE EI =A computer network is defined as two-or more interconnected computers to share resources, exchange data files or two allow electronic communication, +The computers on a network may be linked through, cables, telephone lines, radio waves, satellites or infrared light beams. +A communication network is a collection of switches (nodes) interconnected by transmission, media (links) carrying information signal in. electrical or optical form. Examples of network ; Telephone network, cable TV network, Internet etc Components of — computer (Communication) networks, 1.Node 2. Branch 3. Networks 1.6.1 | Node A node is a point where two or more branches meet. Fig. 1.61 illustrates a typical network. ‘The data from source enters the network through a node called source node similarly data leaving the network from a node towards destination is called destination node. Link or brane. Nodes “A, 8. C inkiBranches : AB, AC, BC ig. 1.6.1 Typical network - TECHRUCAL PUBLICATIONS" An up ta! orkrovedge+ 709 [Fundamentals of Data Communication and Computer Network DData Communication and Computer Network Ls Sr. No, Network Node 1 Telephone network Telephone exchange 2 Data network Router Functions of Node 1. Node acts as buffer and storage for data. Node acts as store and forward switch. 3. To identify incoming data and test free outlet 4. Node performs signaling for the network 4.6.2 | Branch ©A branch of computer network is a transmission medium. The transmission medium can be wire or Wited medium can be pair of copper wires, co-axial cable or optical fiber. The wireless medium can be microwave or infrared. wireless, «The bandwidth of both wired oF wireless medium is, very wide to carry electrical signals, The length of transmission link is limited due to attenuation and distortion. 16.3 Goals at Computer Network + Goals of computer networks are as follows 1. To. provide sharing of suchas information or processors 2. To provide inter process communication among, users and processors 3. It provides the network user with maximum, performance at minimum cost 4. It provides geographically distributed system. 5. It provides compatibility of expiipment and software 6. provides management allocation of network resources. contralized control for a dissimilar centralized and 7. It provides distribution of processing functions. 1.6.4 | Bonefits of Computer Network 1) Organizations today are widely dispersed over in the world. The sites need to exchange information and data. A network provides the means to exchange data among these computers and to make data available to the people of the company. 2) The networking of computers permit the sharing of resources. It also supports the critical function of backup. Backup capability is especially important in system such as those used for air traific control 3) Ik allows Employees can work at home by using terminals tied through networks into the computer at the office. a very flexible working environment. 4) Computer networks reduces cost of sharing data and resources, 5) Computer networks provides reliable connection and communication 8) Network provides standardization of application 7) Computer netwark provides efficient control and administration. 8) Computer network allows remote access to the computer. dso ox naevoriag +The following are the important uses, need and. benefits of a computer network. 1. File sharing : Networking of computers helps the network users to share data files, 2. Hardware sharing : such a Users can share devices CD-ROM. drives, hard drives ete. Without computer networks, device sharing is not possible. 3. Application sharing ; Applications can be shared over the network, and this allows to printers, scanners, implement client/server applications, 4, User communication : Networks allow users to communicate using e-mail, newsgroups and video conferencing ete: 5. Network gaming : A lot of network games are available, which allow multi-users to play from different locations. 6 Voice over IP (VoIP) : Voice over Internet Protocol (IP) is a revolutionary change in felecommunication which allows to send. folephone calls (voice data) using standard Internet Protocol (IP) rather than by traditional PSTN, TECHNICAL PUBLICATIONS”. Anup ns ferrowogeSe ‘Dita Communion snd Compute Nebo 110 Board Questions 1. List adcaniages of computer network CEA ifs: pi bik 3. Give advantages of conprter network 4. State the net of computer network CEO State and explain netavork features. CEEOL 17 Classification of Network : LAN, MAN, WAN + There are many types of computer networks. 17.1 | Local Area Network (LAN) +The IEEE 902 LAN is a popularly used shared medium peer-to-peer communications network that broadcasts information for all stations to receive. +The LAN enables stations to communicate directly. physical without medium any point-to-point switching node being required. +A LAN composed hardware and transmission media and software. basis intermediate is a systom of computer + LANs are privately owned networks within a single building or campus of upto few km. in range. It generally use only one type of transmission medi. + Depends upon application and cost, various topology used in LAN. (eg. star, bus, ring). + The basic idea of a LAN is to provide easy access to Data ‘Terminal Equipment (TEs) within the office These DIEs are not only computers but other devices, such as printer, plotters and electronic files and databases. + Fig. 1.7.1 shows the local area networks, Fig. 1.7.4 LAN Fundamentals of Data Coniston and Computer Network + LAN can provide users 1) Flexibility 2) Speed 3) Reliability 4) Adaptability 5) Security 6) Transparent interface 2) Access to the other LAN and WAN 8) Hardware and software sharing 9) Centralized management 10) Private ownership of the LAN. + Attributes of LAN 1) The LAN transmits data amon; 2) The LAN transmission capacity is more than 1 Mbps, 3) The LAN channel is typically privately owned by the organization usingthe fecility 1 user stations, 4) The geographical coverage of LANS is limited to areas less than 3 square kilometers. LANs are typically identified by the following properties 1. Multiple systems attached to shared! medium. 2. High total bandwidth (-10 Mbps). 3. Low delay. 4. Low error rate. 5. Broadcast / Multicast capability 6. Limited geography (1-2 km). 7. Limited number of stations. 8. Poor relationship hetween stations ©. Confined to private property +The low level protocols used in such environments different networks. are from those used in wide area +The common forms of LAN are those described by the IEEE standard 802, This stendard describes operation upto and including OSI layer 2 Individuals may build what they like on top of these basic protocols, +A commen set of higher level protocols is called TCPAP which provides OSI layer 3 and 4 functionality, on top of this may be found a set of protocols commonly called Telnet protocols. An pte frais‘Data Cominunication and Computer Network un Fundamentals of Dita Communication and Computer Network + At the lowest level the IEBE 802 specifications split into 3 corresponding to three different but common LAN structures, These are - 8023, $024, 8025 standards for topology. LAN are capable of transmitting data at very fast rates, much faster than data can be transmitted over a telephone line ; but the distances are limited, and there is also a limit on the number of computers that can be attached to a single LAN, + The following characteristics differentiate one LAN from another * 1. Topology : The geometric arrangement of devices fon the network. For example, devices can be arranged in a ring or in a straight line. 2 Protocols : The rules and encoding specifications for sending data, The protocols also determine whether the netwark uses a peer-to-peer or client Jeever architecture 3. Media : Devices be by tovistec-pair wire, co-axial cables, oF fiber optic ables. Some networks do without connceting media altogether, instead via radio waves. can connected communicating 4.7.2 | Metropolitan Area Networks (MAN) A MAN, while larger than LAN is limited to city or group of nearby corporate offices. It uses similar technology of LAN, The Metropolitan Area Network standards are sponsored by the IEEE, ANSI and the Regional Bell operating companies. The MAN standard is organized around a topology and technique called Distributed Queve Dual Bus (DDB) Fig. 1.7.2 Wide TECHNICAL PUBLICATIONS: = MAN provides the transfer rates from 34 to 150 Mbps. {MAN is designed with two unidirectional buses Each bus is independent of the other in the transfer Of traffic. The topology can be designed as an open bus or a closed configuration = MANs fiber optic technology and provide high speed interconnection between sites. It can support both data and voice. are based on transmission + MAN as a special category is that a standard has been adopted for them and this standard is now being implemented, It is called! [EEE 802.6. Wide Area Networks (WAN) + A WAN provides long distance transmission of data and voice. ‘+ A Network that covers a larger area such as a city, state, country or the world is called wide area network. «The WAN contains host and collection of machines, User program is installed on the host and machines. |All the host are connected by each other through communication subnet. Subnet carries from host to host messages ‘+ Fig. 17.2 shows the component of WAN, ‘Subnet consists of transmission lines and switching clements. The transmission line is used for data transfer between two machines. Switching elements fore used for connecting tvo transmission lines, Switching elements are specialized computers. It selects the proper outgoing line for incoming data and forward the data on that line. ‘The switching elements are basically computers and they are called packet switching nodes, intermediate area network An ap ttf noeSe work These and data systems switching exchanges. switching elements are also called routers «Each host is connected to 2 LAN on which a router js present. Sometimes the host can be directly connected to the router. The interconnection of routers forms the subnet + In the WAN, when the packet is sent from one router to another via one or more intermediate routers, the packet is received at each intermediate router in its entirety. This packet is stored in that router until the required output line is free. The subnet which uses this principle is called pointto-point, store and forward, or packet switched subnet. + Almost all the WANs use store and forward subnets. +If the packets are small and of same size, they ere also called cells. +In the pointto-point subnet, the router, interconnection topology becomes important, WANs can also use satellite or ground radio system. The routers have antenna, through which they can send or receive data, they can listen from satellite WAN uses hierarchical addressing because they, facilitate routing. Addressing is required to identify which network input Is to be connected to which network output 1.7.4 | Comparison between LAN, WAN and MAN. Parameter LAN WAN MAN ‘Area covered Covers. Cavers. Covers small area, lange larger than ie. within geographic LAN & the alarea.— smallor buileing than WAN, Error rates Lowest. Highest. Moderate Transmission High Low Moderate speed speed. _speed. _speed. Equipment cost Uses Uses most Uses inexpensive expensive moderately’ equipment. equipment. expensive equipment Board Questions 1. List any ttoo characteristics of LAN, T 2. Explain classification of computer network by their geography and dofine. 3, Draw and explain wid CEO ts advantages. Cae Compare WAN and MAN (any 4 points) ro LAN 4. Describe LAN 1 TOSEAS 6. Differentiate between WAN on following points and 7. Distinguish between LAN aud WAN. SBTE : Winter47, Marks 4 1.8 | Network Architectures 1.8.1 | Peorto-Peor Model + In a peer to peer network, there are no dedicated servers or hierarchy among the computers. Fig. L8.1 shows the peer to peer client/ server network. Fig. 1.8.1 Peer to peer clientserver network + All computers are equal, hence the name peer. Each computer in the network can function asa client and/or a server, and no single computer holds the network operating system or shared files. P2P_ networks, network performance actually improves as an increasing number of pears vIn overall An uo ht for rowecgeala Comnmuniclion and Computer Network 115 Fundamentals of Data Comenusiation ane Computes Network are added to the network, these peers can organize i Cove eae hiker ta ase ROR themselves into. ad-hoc groups. as they MSBTE + Summer 47, Marks 4 communicate, collaborate and share bandwidth with, each other to complete the tasks at hand. 3. With neat diagram, explain client server network along with its advantages and disadvantages + Each peer can upload and download at the same time, and in a process like this, new peers can join the group while old peers leave at any time. This dynamic reorganization of group peer members is 4. Compare client server and peer and peer network SEITE: Winter 47, Marks 4 flanperdad (0 endewsers. 5. With neat diagram explain client server network along with its advantages and disadvantages. 1.8.2 | Client-Server Mode! CSTAE) +A client is a machine, typically a personal computer 6. Describe the architecture of client-server network that is equipped with network software twith its acewmntages and disadvantages applications. These applications are designed to request and receive data over the span of the feo 7. Compare peer to peer and elient-sercer netoork CSE) +A server is a storehouse of files, folders, datebases and even more complicated applications. A server is, Tol iro. filaie.Guoeilons with: Anewers; more powerful than a dient and can support and process the request of a large number of clients, at Q1 Define protocol with respect 10 computer time by networking together many servers. the networks, servers can support an enormous amount of clients Ane. /. A pisweeal Ga et Se -raleR Wi Zoe without being overwhelmed by the load. data conmenensation. +The client sends the server a request for data, the server will process the request and proxtuce the closest result to a request and send them back to Q2 List out the jive components of data ‘communication system. Ans. Five components are + L. Message 2. Sender 3. Receiver 4. Transmission medium 5, Protocol Q3 Define computer network. Ans: A computer network consists of two or more computers that are linked in order to share resources, exchange data files or to allow electronic communication 4 Give the advantages of computer network, on u Ans. : Advantages of computer networking. 1. File sharing 2. Resource sharing 3. Sharing a single internet connection the client. 4, Increasing storage capacity. Board Questions. as: \WerweaLAN? 1. State merits and demerits of client server network Ans.: A LAN is a common name used to = describe a group of devices _that - TECHNICAL PUBLICATIONS" kn up thet fer lowingay Data Communication and Computer Network 0% Lu Fundamentals of Daia Communication ard Computer Network ‘geographic location building or campus. a6 Ans. LAN is limited to single Differentiate bit rate and baud rate Baud rate is number of pulses per second that are sent on a given wire, The bit rate is the number of bits of data that are transmitted on a xiven wire per second, Q7 On which jeaures a LAN can be aifferentiated ? Ans.: 1) Topology 2) Protocol 3) Media for transmission. 8 — What are advantages of LAN ? ‘Ans. : 1) Flexiblility 2) Speed 3) Reliability 4) Resource sharing 5) Centralized management. 6) Privately owned network. Q9 hot is the need of standords ? Ans. : Standards are necessary to ensure that products from different manufacturers can work together as expected. @.10 State major categories of computer network 1) Local Area Networks (LANs) 2) Metropolitan Area Network (MANs) Ans. 3) Wide Area Networks (WANs) 11 What is data communication ? cr So Ans.: Data communication is exchange of data between two devices by a transmission medium. ooo TECHNICAL PUBLICATIOUS”. An p thst forhnoledgeData Communication and Computer Netwark ras Fundamental of Data Communication and Computer Neswerk PAICSL PUBLICATIONS”. Anup torinoTransmission Media and Switching 2.1 | Guided Transmission Met CS * The transmission medium is the physical path between transmitter and receiver in a data transmission system, In transmission medium, communication is in the form of electromagnetic *Guided media is also called Bounded media Depending on the type of transmission medium used the bounded media can be further classified into three types. 1. Twisted pair cable 2. Co-axial cable 3. Fiber optic cable. Twisted Pair * Twisted pair is least expensive and most widely used. A Twisted Pair (TP) consists of two insulated copper wires arranged in ‘a regular spiral pattern. A. wire pair acts as a single communication link + TP may be used to transmit both analog and digital signals. For analog signals amplifiers. are. required about every 5 to 6 km. For digital signals, repeaters are required every 2 or 3 km. © TP is most commonly used medium for in. the telephone network. Compared to other commonly used transmission media, TP is limited in distance, bandwidth and data rate when two copper wires conduct electric signal in close proximity, a certain amount of Electromagnetic Interference (EMD) ‘occurs. This type of interference is called cross talk ‘Twisting the copper wire reduces cross talk. + Twisted pair cable comes in two varieti 1. Unshielded Twisted Pair (UTP) Cable 2. Shielded Twisted Pair (STP) Cable. 2.1.4.1] Unshielded Twisted Pair (UTP) Cable + UIP is a set of twisted pairs of cable within a plastic sheet UTP is ordinary telephone wire, This js the least expensive of all the transmission media commonly used for LAN and is easy to work with and simple to instal. sUIP is external electromagnetic interference. Category 3. and Category 5 UTP are subject to commonly used in computer networks. UTP can transfer data at 1 to 100 Mbps over a distance of 100 meters, The difference between cat and cat5 cable is the number of twists in the cable per unit distance. cat5 is much more tightly twisted, Fig. 21.1 shows the UTP cable. ree Fig, 2.1.1 Unshielded four pair cablo +The Electronic Industries Association (EIA) has doveloped standard to grade UTP cable by quality Category 1 (cat 1) as the lowest quality and catogary 5 (cat 5) as the highest quality. Use of each category cable is as follows : Category 5 Used in local area network, It support upto 100 Mbps data transmission speed. Category 4: It support transmission speed of 16 Mbps and three twist per foot Category 3: It support data transmission speed upto 10 Mpbs, At least three twist per feet and used in telephone system, 9Dita Communication and Computer Network Category 2: It support data transmission speed upto 4 Mbps transmission. and suitable for voice data Category 1: Mostly used in telephone system. Cath is suitable for voice and low speed data ‘communication. Characteristics of UTP + UTP has the following characteristics 1. ‘Transmission rate of 10 - 100 Mbps. 2. UTP is less expensive than FOC and co-axial cable. 3. Maximum cable segment of UTP is 100 meter: 4. UTP cable is very flexible and easy to work 5. UIP uses BJ - 45 connector: 6. Most susceptible to electrical interference or cross talk ‘Advantages of UTP 1, UTP is easy to terminate. 2. Cost of installation is less. 3. High instolled base. Disadvantages of UTP 1. Teis very noi 2. It covers less distance. 3. UTP suffers from interference, Shielded Twisted Pair (STP) Cable + STP offers a protective sheathing around the copper Wwite, STP provides better performance at lower data rates. They are not commonly used in nebyorks. + Installation of STP is easy. Special connectors are required for Cost is moderately expensive. Distance is limited to 10 meters for 500 meters. STP. suffers from outside interference but not as much UTP. Fig,21.2 shows the STP cable. installation Applications of TP Cable 1. Twisted pair cable used for both analog and digital signals. 2. Twisted network. pair cable are used in telephone ‘Transmission Media and Switehing I Fig. 2:1.2 Shielded Twisted Pair (STP} cable 3. In LAN, TP wires are mainly use for low cost, low performance applications. 2113] Comparison of Ure and STP SENG. Tammeer | UTP sr 1 Datarate 1M) Mbps 180 Mbps 2) Cibletnghh AOD) 500 mete S| Geaiol | Mos Less eS, le to suscepible to factions or terrence cr ios ae cros talk Ee. Ben haat E Cost Towest Lite conty 22 | Coaxial Cable Tt is made up of two conductors that share the common axis, It consists of a hollow outer cylindrical conductor that surrounds a single inner wire conductor, + Co-axial cable is used to transmit both analog and digital signals. Data transfer rate of co-axial cable is used to transmit both analog and digital signals, Data transfer rate of co-axial cable is in between TP and fiber optic cable. + Co-axial cable is classified by size (RG) and by the cable resistance to direct or alternating electric currents. Following are co-axial cable commonly used in networking. RG means Government Ratings. ¥ TEGHIIGAL PUELEATNS'- An ptt riouseta Communication aad Computer Network 2a = 50 ohm, RG-8 and RG-LI for thick Ethemet. #50 ohm, RG-58 used for thin Ethernet «75 ohms, RG-59 used for cable TV. #93. ohm, RG-62 used for ARC net ‘It is relatively in-expensive, The cost for thin co-axial cable is less than STP. Thick co-axial is moro expensive than STP. Installation is relatively simple, Coraxial cable must be grounded and terminated. “+ A typical data rate for today’s co-axial network is 10 Mbps, although potential is higher. It suffers from attenuation, Fig, 2.1.3 shows the co-axial cable, rating MOREY pong ogee et Fig. 2.1.3 Conaxial cable 1. Characteristic of co-axial cable : + Co-axial cable has the following characteristics 1.10 Mbps is the transmission rate. 2, Maximum cable length for thinnet is 185 meters and for thicknet is 500 meters. 3, Flexible and easy to work with thinnet. 4. Ethernet designation to 10 base 2 (thinnet) or 10 base 5 (thicknet). 5. Less expensive than fiber optics cable but more expensive than twisted pair 6. Good resistance to electrical interference. . Advantages of co-axial cable 1. Cosanial cable used for both ive, analog and digital data transmission. It has higher bandwidth. Easy to handle and relatively inexpensive as compared to fiber optic cables data. transmission, 4, Tkuses for longer distances at higher data rates. 5. Excellent noise immunity 3. Disadvantages of co-axial cable : 1. Distance is limited, ‘Tranemision Media and Switching 2. Number of node connection is limited 3. Proper connectors and termination is must 4, Applications of co-axial cable 1. In analog and digital data transmission. In telephone networks. In Ethernet LANs. In cable television network. 2424 Baseband and Breadsand Coaxial Cable ‘= Baseband coaxial cable transmits a single signal at a time at very high speed. A baseband cable is mainly used for LANS. ‘ Basehand coaxial cable supports frequency range of a4 kHz and is used for digital signaling. These types of cables are 50 ohm cables used for ‘digital transmission’ ‘+ Longer cables can be used with low data rates or periodic amplifiers «The baseband co-axial cable was originally used for the Ethemet system that operates at 10 Mbps. They use standard cable television technology. The maximum length of baseband co-axial cable between two repeaters is dependent on the data rates. + Broadband many simultaneous signals using different frequencies. It supports the frequency range above 4 kil and are used for analog signals. coaxial cable can transmit ‘Broadband coaxial cable is used with a modem. ‘The digital signal inserted on these cables is encoded using Manchester or Differential Manchester coding. ‘The digital signal consumes the entire frequency spectrum of the cable. So it is not possible to transmit multiple channel using FDM. ‘The transmission of digital signal on the cable is bi-directional «Broadband coaxial cables are 75 ohm cables used for analog transmission 2.1.3 | Fiber Optic Cable A fiber optic cable is a light pipe which is used to carry a light beam from one place to another. ¥ TECHOICAL PUBLICATIONS”- Anup tut for outsData Communication and Computer Network “Transmission Media and Switching Light is an electromagnetic signal and can be modulated by information. Since the frequency of light is extremely high hence it can accomodate wide bandwidths of information, also higher data rate can be achieved with excellent reliability The modulated light travel along the fiber and at the far end, are converied to an electrical signal by means of a photo electric cell, Thus the original input signal is recovered at the far end. + FOC transmits light signals rather than electrical signals, plastic that conducts light The inner core is surrounded by cladding a layer of glass that reflects the light back into core Each fiber has a inner core of glass or +A cable may contain a single fiber, but often fibers are bundled together in the centre of the cable. + FOC may be multimode or signal mode. Multimode fibers use multiple light paths whereas signal mode fibers allow a single light path and are typically used with laser signaling, It has greater bandwidth. 2.4.3.1] Types of Fiber ‘There are three varieties of optical fibers available Al three varieties are constructed of either glass, plastic, or a combination of glass and plastic. The three varieties are 1. Plastic core and cladding 2 Glass core with plastic cladding (often called PCS fiber, plastic-clad silica) 3. Glass core and glass cladding (aften called SCS, silica-clad silica) 1. Plastic core and cladding : «Plastic fibers have several advantages over glass fibers. First, plastic fibers are moro flexible and, consequently, more rugged than glass. They are easy to install, can betler withstand stress, are less expensive and weigh approximately 60 % less than. glass. +The disadvantages of plastic fibers is their high attenuation characteristic; they donot propagate light as efficiently as glass. Consequently, plastic fibers are limited to relatively short runs, such as within a single building or a building complex. 2. Glass core with plastic cladding = + Fibers with glass cores exhibit low attenuation characteristics. However, PCS fibers are slightly better than SCS fibers. Also, PCS fibers are less affected by radiation and are attractive to military applications. therefore more 3. Glass core and glass cladding = «SCS fibers have the best propagation characteristics and they are easier to terminate than PCS fibers Unfortunately, SCS cables are the least rugged and they are more susceptible to increase in attenuation when exposed to radiation +The selection of a fiber for a given application is a function of specific system requirements, There are always trade-offs based on the economics and logistics of a particular application, 2.1.32] Modes of Fibar + Fiber cables can also be classified as per their mode Light rays propagate asan clectromagnetic wave along the fiber. The two components, the electric ficld and the magnetic ficld form pattems actoss the fiber These pattems are called modes of transmission. The mode of a fiber refers to the number of paths for the light rays within the cable, According to modes optic fibers can be classified into two types 4) Single mode fiber. ii) Multimode fiber. + Single mode fiber allows propagation of light ray by only one path, And multimode fiber allows multiple paths for light ray to propagate. The number of modes (N) is given by the formula, where 4d = Diameter of core Numerical aperture - TECHNICAL FUBLICATIONS”- An wp thst fr kaon‘Data Communication and Computer Nework + 70% “Transnision Media and Switching 1 = Wavelength of light ray 2.1.3.3 | Fiber Optic Configuration =Depending on the refractive index profile of fiber and modes of fiber there exist three types of optical fiber configurations. These optic-iber configurations 4) Single-mode step-index fiber. ii) Multimode step-index fiber. iii) Multimode graded-index fiber. Single-Modo Stop-indox Fiber ‘In single-mode step-index fiber has a central core that is sufficiently small so that there is essentially only one path for light ray through the cable. The light ray is propagated in the fiber through reflections «+ Typical core sizes are 2 to 15 mm. The disadvantage of this type of cable is that because of extremely mall size interconnection of cables and interfacing with source is dificult. ‘Multimode Stop-Index Fiber ‘+ Multimode step-index fiber is most widely used type. It is easy to manufacture. Its core diameter is 50 to 1000 mm i.e. large aperture and allows more Tight 0 enter the cable +The light reys are propagated down the core in zigzag manner, There aze many paths that a light ray mey follow during the propagation. ‘Multimode Graded-indox Fiber * The core size of Multimode graded-index fiber cable is varying from 50 to 100 mm range. + The light ray is propagated through the sefeaction. ‘The light ray enters the fiber at many difforent angles. As the light propagates across the core toward the center it is intersecting a less donse to more dense medium. # The light rays are being constantly being refracted and ray is bending continuously. This cable is mostly used for long distance communication 34) Characteristics of Fibre Optic Cable + Fibre optic cable has the following characteristics 1. Transmission rate of 100 Mbps, 2. Not affected by the electrical interference. 3. Most expensive cable, FOC support cable length of 2 km or more, It supports voice, video and data, It provides most secured media, Commonly used as backbones between buildings and token ring networks. Not very fle le, difficult to work. 13.5] Advantages and Disadvantages of Optical Fiber Advantages 1 10. n. 2. Wide bandwidth : The light wave occupies the frequency range between 210"? Hz to 3.7107 He, Low losses : Fiber optic cables offers less signal attenuation over long. distances. Typically it is less than 1 dB/km, Immune to cross talk : Since fiber optic cables, are non-conduciors of electricity hence they do not produce magnetic field, ‘Thus fiber optic cables are immune to cross talk between cables caused by magnetic induction Interference immune : Fiber optic cables are immune to conductive and radiative interferences caused by electrical noise sources such as lightening, electric motors, fluorescent lights. Light weight : As fiber cables are made of silica glass or plastic which is much lighter than copper or aluminium cables. Small size ; The diameter of fiber is much smaller compared to other cables, therefore fiber cable is small in size, requires less storage space. More strength : Fiber cables are stronger and rugged hence can support more weight Security : Fiber cables are more secure than other cables. It is almost impossible to tap into a fiber cable as they do not radiate signals Long distance transmission : Because of less attenuation transmission at a longer distance is possible. Environment immune : Fiber cables are_more immune to environmental extremes. They can operate over a large temperature variations. Safe and easy installation : Fiber cables are safer and easier to install and maintain, Long term cost of fiber optic system is. less compared to any other system. $ TECHNICAL PUBLICATIONS". Anup thusterArowedgeData Commtnication and Computer Network Disadvantages 1. High initial cost systems, “Transmission Media and Switching The initial installation or setting up cost is very high compared to all other 2 Maintenance and repairing cost : The maintenance and repairing of fiber optic systems is not only difficult but expensive also. G50 MH) 4 Sapport moderately high data rates. (500 Mbps) 2:4 | Comparison between Casal, TP and FOC & Coil cable Twisted par eable MD) tases peeeeetaeees ae eee 2 Leo lft by EM Ace by ML 3. Bandwidth is moderacy High | Rendwh wlw @ Support low dats sates. (4 Mbps) Fiber optic cable FOC uses optical form of signal lover 2 glass fiber Not affected by EM, Bandwidth is very high. (2 GHz) Data rates és very high. (@ Gbps) 5. Moderately costly Cheapest. Costly 6 Repeater spacing is I-l0 km. Repeater spacing 2- 10 km. Repeater spacing is 10 = 100 km JW supports all radio Support all sedi frequencies Frequency range is 902 MHz ta frequencies. 328 Miz 4 __Low attemuation. High attenuation. Very low attenuation 22 F Board Questions 1. What are different transmission media ? With the help of neat diagram, describe working of fiber optic cable, Drato a sketch of shielded twisted pair cable and describe any two characteristics State the advantages of fiber optic cable. 5. State any two advantages af coaxial cable 8 Dr 9. Desc 10, Deseribe any four adonntages of fib 11, Why the network enble is teuisted ? Describe the construction of fiber optic cable with no and explain twisted pair cable 6. Describe adowntages unul disaountages of optical fibre cable be any four physical characteristics of fiber optic cable optic cable 12, State any tro advantages of co-axial cable. Unguided Transmission Media roa ver-t7, Marks 4 use rz] = oar SSSEME) SALE Coe rz] CEEESSALO SETI ACRE ‘For long distance broadcasting transmission unguided media like microwave links are chosen, ‘= Unguided media is also called Unbounded media or wireless media,Data Communication nel Computer Network ‘Transmission Media and Switching + Unguided media relates to data through the air and is commonly referred to as wireless, The transmission and reception of data is transmission carried out using antenna, + Physically, there is no direct physical connection, between two points such as microwave and satellite links. Your mobile phone unguided transmission medium, also uses 2.2.1] Radio Wave + Radio waves have frequencies between 10 kilohertz (KHz) and 1 gigahertz (GHz). Radio waves include the following types. @) Short wave 1b) Very High Frequency (VHF) television and FM radio. © Ultra High Frequency (UHF) radio and television. The range of frequency and type of medium used for their transfer is shown in Fig. 221. + Radio waves can broadcast omni directionally or directionally. Yarious kinds of antennas can be used to broadcast radio signals. The power of the Radio Frequency (RF) signal is determined by the antenna and transreceiver (a device that TRANSmits and FoCEIVES a signal over a medium such a copper, radio waves oF fiber optic cables). Radio frequency characteristics «Some of the characteristics of radio waves are as follows a) Radio waves are easy to generate ) They can travel long distances ©) They can penetrate buildings easily so they are widely used for communications both indoors ancl outdoors. ) Radio waves are om they travel in all directions from the source, so that the transmitter and receiver do not have to be carefully aligned physically ©) The properties of radio waves are frequency dependent, At low frequencies, radio waves pass through obstacles well, but the power falls off sharply with distance from the source. + At high frequencies, radio waves are subject to interference equipment. from motors and other clectrical ‘+ Low frequency and medium frequency range cannot be used for data transfer because of their vary small bandwidth 2.2.2 Microwave Above 100 MHz, the waves travel in straight lines and can therefore be narrowly focused Concentrating all the energy into a small beam using a parabolic antenna (like the satellite TV dish) fitz) 5 1040" 0° 10° 10° _t0'*_10"° 10° 10° 10% 10° Y Wig Tanna reso | MoT wirarea [Juv] X-ray | Camm Visitfe ight spectrum ~>*~ toe) 10h 10° 40° 10” 40° a0? _ 10° 40" 10° 10” 10-10% 10” \ Frequency band FF Wee are or Fig. 2.2.4 Radio froquoney and transmiesion media An up tnt orineadseala Comnmuniclion and Computer Network ‘Tranemision Media and Switching Recaing Fig. 2.2.2 Microwave communication gives a much higher signal to noise ratio, but the transmitting receiving accurately aligned with each other and antennas must be «+ Before the advent of fiber optics, these microwaves formed the heart of the long distance telephone transmission system + In its simplest form the microwave link can be one hop, consisting of one pair of antennas spaced as little as one or two Kilometers apart or can be a backbone, including multiple hops, spanning several thousand kilometers +A single hop is typically 30 to 60 km in relatively flat regions for frequencies in the 2 to § GHz bands, ‘When antennas are placed between mountain peaks, a very long hop length can be achieved. Hop distances in excess of 200 km ere in existence. The line-of-sight” nature of microwaves has some very attractive advontages over cable Line-of-sight is a term which is only correct when deseribing microwave paths ystems. partially + Atmospheric conditions and certain effects modify the propagation of microwaves so that even if designer can see from point A to point B (true line of sight), it may not be possible to place antennas at those and achieve a communication performance. two points satisfactory In anler to overcome the problems of line-of-sight and power amplification of weak microwave systems use repeaters at intervals of about 25 to 30 km in between the transmitting receiving stations signals, +The first repeater is placed in line-of-sight of the transmitting station and the last repeater is placed in line-of-sight of the station. Two consecutive repeaters are also placed in line-of-sight fof each other. The data signals are received, amplified and retransmitted by each stations receiving of these + The objective of microwave communication systems is fo transmit information from one place to another without interruption and clear reproduction at the receiver. Fig. 22.2 indicates how this is achieved in its simplest form, Microwave transmitter and receiver Fig. 2.23 shows block diagram of microwave link transmitter and receiver section, «The voice, video or data channels are combined by a technique known as multiplexing to produce a BB - TECHNICAL PUBLICATIONS" kn up thet fer kouingsata Communication and Computer Network 2.9 “Teanemission Media and Switching g sf = ! wie, Teme} [Tmcae [meme] then a ae sieciconanes nn Cea ee () Microwave receiver Fig. 2.2.3 Microwave transmitter and receiver signal, This signal is frequency modulated to an IF and then upconverted (heterodyned) to the RF for transmission through the atmosphere. The reverse Process occurs at the receiver. The microwave transmission frequencies are within the approximate range 2 to 24 GHz. +The frequency bands used for digital microwave radio recommended by the CCIR. Each recommendation clearly defines the frequency range, the number of channels that can be used within that range, the channel spacing the bit rate and the polarization possibilities. Characteristics of microwave communications Microwave transmission is weather and frequency dependent. ‘The frequency band of 10 GHz is in the routine use. Microwave communication is widely used for long distance telephone communication, cellular telephones, television distribution and other shortage of spectrum developed. Following are the important characteristics of Microwave communications uses that a severe has a) Microwave is relatively inexpensive as compared. to fiber optics system. For example, putting up two simple towers and antennas on each one may be cheaper than burying 50 km of fiber Uwough a congested area or up mountain and it may also be cheaper than leasing the telephone line tower a b) Microwave systems permit data transmission rates of about 16 Giga (1 giga = 10°) bits per At such high frequencies, microwave systems can carry 250,000 voice channels at the same time. They are mostly used to link big ‘metropolitan cities where have heavy telephone traffic between them, second, Limitations of Microwave Communication «Since microwaves travel ina straight line, if the towers are too far apart, the earth will get way. Consequently, repeaters needed perioclically. The higher the towers are, the further apart they can be, The distance between repeaters goes up very roughly with the square root of the tower height. For 100 meter high towers, repeaters cean be spaced 80 km apart the Applications of Microwave Communication + Microwave mostly used in following, applications. 1. Mobile telephone network communication, communication is, 2. Wireless LAN. 3. Point-to-point communication between stations. 4. Line-of-sight communication 2.2.3 | infrared + Unguided infrared light (wave) are widely used for ‘The remote control short range communication, 7 TECHNICAL PUBLICATIONS". Anup tas knoeData Communion and Compoter Network 2 Transmission Manta and Satehing used in TV, VCR and stereos all use infrared communication. They are relatively directional, cheap and casy to build, but have a major drawback : They do not pass through solid objects. On the otter hand, the fact that infrared waves do not pass through solid walls well is also a plus. ‘st means that an infrared system in one room of a building will not interfere with a similar system in adjacent rooms. Security of infrared eystem against evasdropping is better than that of radio system precisely for this reason, infrared light is suitable for indoor wireless LAN. For example, the computer and offices in a building can be equipped with relatively unfocused infrared transmitters and receivers, The portable computer capability can be on the local LAN without having to physically connect to it, Infrared communication cannot be used outdoors because the sun shines as with infrared brightly in the infrared as in the visible spectrum, Applications of Infrared Transmission 1. In remote control of home appliances : eg, TV, VCR, VCD and DVD players Indoor wireless LANs. 3. Communication between inhouse electronic gadgets such as keyboard, mouse, printers, scanners and for contralling fan, air conditions. 2.2.4 | Satellite Communication A satellite is a physical object which revolves around earth at known height (oxbit).Artificial satellites are launched into orbits for various. purposes, + One of the mejor application of satellite is in communications, Satellite commumication services have become more reliable and affordable now a days ‘Satellite communication systems offer more flexibility than submarine cables, underground With the satellite to possible to cables, fiber-optic systems, satellite communication, it is communicate with any point on the globe. A satellite system basically consists of a satellite in space and many earth stations on the ground which are linked with each other through the satellite. A ground based station controls the overall operations of satellite. A satelite receives the signal transmitted from the carth station, it then processes or amplifies. the signal and then it rotrancmits the signal back to earth in the desired form, This processing is done by a radio repeater which is transponder, also called as =A communication satellite is @ microwave repeater station that permits two or more users to deliver or exchange information simultaneously. ‘Satellite rotates around the earth at some height. The path of satellite around the earth is called as obit. = Tho satellite moves in specified orbit because of centripetal acceleration. The centripetal caused by the inertia of satellite balances the gravitational attractive force of the earth. force is, ] sSlonats Fig, 2.9.4 Concept of multiplex 2.3.2 | Frequency - Division Multiplexing (FM) + In Frequency-Division Multiplexing (FDM), multiple signals share the bandwidth of a common communication channel. FDM Transmitter «+ Fig. 2.32 shows a general block diagram of an FDM uansmitier system +All signals to be transmitted feed a modulator circuit. The carrier for each modulator (f) is on a different frequency + The carder froquoncies are usually equally spaced from one another over a specified frequency range. ong oa modulates carriers | SS ens sora — [a ee vane Astana cam sie sion 2—- [rom ein Sand Liar Carrier foo — “Transmitter ints —-[ a ona Acasa Caner fe ‘combined into a - aan wpm — i Salat egies Fig, 23.2 FOM transi TECHNICAL PUBLICATIONS". Anup ims rinewtageData Commuention and Compoter Network 2s Transmission Masia and Saitehing Bandpess fies elect outindiadual channels ) origina sionals = i ‘| £[pemoasator}—= 1 Antenna Signal received domoduatedinto compose sgnat — ‘te. | —+[[Demoauietor | —~ 2 Recover |—-|Demeduator BFF a |_frsaaiaer] —~3 Dents recover original signals Damedivator |» 0 } Fig, 23.8 FDM receiver The modulated signals are then combined into a | Concept of TDM single composite signal to sent over a media link. +A single path and carrier frequency is used. Each user is assigned a unique time slot for their FDM Receiver + Fig. 2.3.3 shows a general block diagram of an FDM operation, *TDM can be used with both digital and analog receiver system. signals, ‘*Demultiplexing is done at receiver. Demultiplexer uses number of filters to decompose the multiplexed signal into constituent signals. to the next in a specific, predictable sequence and time. ‘=A central switch, or multiplexer, goes from one user +The decomposed signals are then passed through. demodulater and band pass filter that separates original baseband signal from earner Thus. baseband signal is recovered. 1. What is multiplexing. Give its types. 2. Wha i mtiplxing 7 List types of multiplexing iplexing (TDM), each signal cand explain auy one. entire bandwidth of the channel. Board Questions Time Division Multiplexing (TOM) ln Time-Division Mul ‘occupies the sional t Sonata [ Sona [Sima] | be one frame et ine Note: Equal tme siots } for each signal Fig, 2.3.4 TDM concopt Ca TECHNICAL PUBLICATIONS” Anup tnusterknowteaeeim Data Communication and Computer Network pa “Teerwnsion Mea and Switching 2.4 | switching and time delay characteristics. This kind of ‘+ For data transmission, different types of switching methods are possible. There are packet switching, circuit switching and hybrid switching. Hybrid switching uses some of the properties of packet switching and circuit switching and random access switching. ‘In random access, all attached devices and facilities share a single high speed channel, In. the simplest mode of random access, devices transmit when they want to but listen to the channel to see if they have collided with other transmissions, If so, they retransmit after a random amount of time, Random access is widely used in LAN and satellite networks, 2.4.1 | Concepts of Circuit Switching ‘+ Circuit switching is most preferred in telephone networks, Telephone networks are connection before the actual transfer of information can take place. + An end-to-end path setup beginning of a session, dedicated to the application, and then released at the end of session. This is called ciruit switching. Circuit switching is effective for application switching is effective for application which make comparatively steady use of channel. Fig. 2.4.1 shows the circuit switching, +For application which need greater performance than these dial up lines can offer, telephone companies offer specially conditional lines. These lines both from the phone ta the office and between phone offices, provide better frequency response conditioned line is leased by the user. The term dedicated and leased are used when the phone company has set a side a conditional line for a communications link, 4. Routing in Circuit Switching Network + Many circuit connection is required in large circuit switched network. The path is established between more than one switch, + When subscriber placed call, network must find the route from calling subscribe to the called subscriber. It passes through the number of switches and trunks + Routing strategy depends upon efficiency and +Number of required sivitehes trunks are minimized in the network and «Network must provide @ reasonable level of service tunder heavy load. Normally routing is telecommunication networks simple in public «Networks were organized into a tre structure or hierarchy + Dynamic routing is one of the method in which routing decision are influence by current traffic conditions. + Altemate routing is used in the circuit switching networks. ‘Swijching orice Fig. 24.1 Circuit switching ¥ TECHNICAL PUBLICATIONS”- Anup rast fr noun