Computer Fundamentals

1. C Co om mp pu utter er F Fun und da am men entta alls s: : P Prrad ade eep ep K K.. S Siinha nha & & P Prriiti ti S Siinha nha Ref. Page Data Communications and Computer Networks Data Communications and Computer Networks Computer Fundamentals Professor Dr. Md. Ismail Jabiullah Department of CSE Daffodil International University

2. Learning Objectives In • • this chapter you will learn about: Basic elements of a communication system Techniques, channels, and devices used to transmit data between distant locations Types of computer networks Communication protocols and their use in computer networks Internetworking tools and their use in building large computer networks Characteristics and advantages of distributed data processing • • • • Ref. Page 320 Data Communications and Computer Networks Slide 2/36

3. Communication Basic Elements System of a Medium Carries the message Receives the Creates and sends message a message Ref. Page 321 Data Communications and Computer Networks Slide 3/36 Receiver (sink) Sender (source)

4. Transmission Modes Data (a) Simplex OR (b) Half-duplex AND (c) Full-duplex Ref. Page 321 Data Communications and Computer Networks Slide 4/36 Receiver (and Sender) Sender (and Receiver) Receiver (or Sender) Sender (or Receiver) Receiver Sender

5. Data Transmission Speed • Bandwidth: Range of frequencies available for data transmission. It refers to data transmission rate. Higher the bandwidth, the more data it can • Baud: Unit of measurement of data transmit transfer rate. Measured in bits per second (bps) Ref. Page 322 Data Communications and Computer Networks Slide 5/36

6. Data Transmission Speed Category Narrowband: Sub-voice grade channels in range from 45 to 300 baud. Mainly used for telegraph lines and low-speed terminals Voiceband: Voice grade channels with speed up to 9600 baud. Mainly used for ordinary telephone voice communication and slow I/O devices • • Broadband: High speed channels with speed up to million baud or more. Mainly used for high-speed computer-to-computer communication or for simultaneous transmission of data 1 • Ref. Page 322 Data Communications and Computer Networks Slide 6/36

7. Data Transmission Media The most commonly used ones Twisted-pair wire (UTP cable) Coaxial cable Microwave system are: • • • • • Communications satellite Optical fibers Ref. Page 323 Data Communications and Computer Networks Slide 7/36

8. Unshielded Cable Twisted-Pair (UTP) Ref. Page 323 Data Communications and Computer Networks Slide 8/36

9. Coaxial Cable Central copper wire PVC insulation Copper mesh Outer PVC shield Ref. Page 323 Data Communications and Computer Networks Slide 9/36

10. Microwave Communication System Receiving antennas Transmitting antennas In between repeaters Transmitting station Receiving station Line of sight Line of sight Line of sight Ref. Page 324 Data Communications and Computer Networks Slide 10/36

11. Satellite Communication System Satellite in space 6 GHz 4 GHz Uplink Downlink Receiving station on earth Transmitting station on earth Ref. Page 325 Data Communications and Computer Networks Slide 11/36

12. Optical Fiber Communication System Optical fiber Electrical signal Electrical signal Amplifier Receiver Sender Light waves Ref. Page 326 Data Communications and Computer Networks Slide 12/36 Electrical to light wave converter Light to electrical wave converter

13. Digital and Analog Data Transmission • Analog signal: Transmitted power varies over a continuous range. Example: sound, light, and radio waves • Digital signal: Sequence of voltage pulses represented in binary form • Computer telephone generated data signal is digital, whereas lines carry analog signals (Continued on next slide) Ref. Page 327 Data Communications and Computer Networks Slide 13/36

14. Digital and Analog Data Transmission (Continued from previous slide) • When digital data is to be sent over an analog facility, digital signals • Conversion of modulation • Conversion of demodulation must be converted to analog form digital signal to analog form is known as analog signal to digital form is known as • Digital transmission of data is preferred over analog transmission transmission of data due to lower cost, higher speeds, and lower error rate Ref. Page 329 Data Communications and Computer Networks Slide 14/36

15. Analog and Digital Signals Voltage +v t 0 1/f 2/f -v (a) Analog signal v 1 1 1 1 0 t (b) Digital signal Ref. Page 328 Data Communications and Computer Networks Slide 15/36 0 0 0

16. Network Topologies • Term network topology refers to the way in which the nodes of a network are linked together • Although number network topologies four major ones are: • Star network • Ring network • Completely connected network are possible, • Multi-access bus network Ref. Page 338 Data Communications and Computer Networks Slide 16/36

17. Star Network Host Node Ref. Page 339 Data Communications and Computer Networks Slide 17/36

18. Ring Network Ref. Page 339 Data Communications and Computer Networks Slide 18/36

19. Completely Connected Network Ref. Page 340 Data Communications and Computer Networks Slide 19/36

20. Multi-Access Bus Network Computers (nodes) Single communication line shared by all nodes Ref. Page 341 Data Communications and Computer Networks Slide 20/36 e communication line shared by all

21. Hybrid Network Completely connected Ring Star Ref. Page 341 Data Communications and Computer Networks Slide 21/36

22. Network Types • Networks are broadly classified into two types: Local Area Network (LAN) and Wide Area Network (WAN) • Local Area Network (LAN) as compared to WAN: • Limited to a small geographic coverage • Has much higher data transmission rate • Experiences fewer data transmission errors • Has lower data communication cost • Typically owned by a single organization • Networks that share some of the characteristics of both LANs and WANs are referred to as Metropolitan Area Network (MAN) Ref. Page 342 Data Communications and Computer Networks Slide 22/36

23. Communication Protocols • Protocol is a set of formal operating rules, procedures, or conventions that govern a given process • Communication protocol describes rules that govern transmission of data over communication networks • Roles of communication protocol: Data Data Data Flow sequencing routing formatting control • • • • • Error control (Continued on next slide) Ref. Page 343 Data Communications and Computer Networks Slide 23/36

24. Communication Protocols (Continued from previous slide) • Precedence and order of transmission • Connection establishment and termination • Data security • Log information. • Communication protocols are normally split up into a series of modules logically composed of a succession of layers. • Terms protocol suite, protocol family, or protocol stack are used to refer to the collection of protocols (of all layers) of a network system Ref. Page 343 Data Communications and Computer Networks Slide 24/36

25. Network Interface Card (NIC) • Hardware device that allows a computer to be connected to a network, both functionally and physically • Printed circuit board installed on to one of the expansion • Provides a attached slots of computer port on the back to which network cable is Ref. Page 344 Data Communications and Computer Networks Slide 25/36

26. The OSI Model The Open System Interconnection (OSI) model is framework for defining standards for linking heterogeneous computers in a packet switched network Standardized OSI protocol makes it possible for any two heterogeneous computer systems, located anywhere in the world, to easily communicate with each other • • Separate set of protocols is defined for each layer seven-layer architecture. Each layer has an independent function in its • Ref. Page 344 Data Communications and Computer Networks Slide 26/36

27. Layers, Interfaces, and Protocols in the OSI Model Node 2 Node 1 Application protocol Presentation protocol Session protocol Transport protocol Network protocol Data-link protocol Physical protocol Network Ref. Page 346 Data Communications and Computer Networks Slide 27/36 Process B Layer 7 (application) Interface Layer 6 (presentation) Interface Layer 5 (session) Interface Layer 4 (transport) Interface Layer 3 (network) Interface Layer 2 (data link) Interface Layer 1 (physical) Process A Layer 7 (application) Interface Layer 6 (presentation) Interface Layer 5 (session) Interface Layer 4 (transport) Interface Layer 3 (network) Interface Layer 2 (data link) Interface Layer 1 (physical)

28. 2 2 An e ex xa amplle e i il ll lus st tr ra at ti ing t tr ra ans sf fe er r o of f me es ss sa age e M f fr ro om s se endi ing no ode e t to o t the e r re ec ce ei iv vi ing no ode e i in t the e OSI I mo ode ell: : Hn n, , header added by layer n:T , trailer header added by layer n:Tn n, trailer a adde ed by y lla ay ye er r n.. Receiving node Sending node Ref. Page 348 Data Communications and Computer Networks Slide 28/36 Process A H7 M H6 H M 7 H5 H6 H7 M H4 H5 H6 H7 M1 H4 H5 H6 H7 M2 H3 H4 H5 H6 H7 M1 H3 H4 H5 H6 H7 M2 H2 H3 H4 H5 H6 H7 M1 T2 H2 H3 H4 H5 H6 H7 M T2 Process B H7 M H6 H7 M H5 H6 H7 M H4 H5 H6 H7 M1 H4 H5 H6 H7 M2 H3 H4 H5 H6H7 M1 H3 H4 H5 H6 H7 M2 H2 H3 H4 H5 H6 H7 M1 T2 H2 H3 H4 H5 H6 H7 M T2

29. Internetworking • Interconnecting two or more networks to form a single network is called internetworking, and the resulting network is called an internetwork • Goal of internetworking is to hide details of different physical networks, so that resulting internetwork functions as a single coordinated unit • Tools such as bridges, routers, brouters, and gateways are used for internetworking • The Internet is the best example of an internetwork Ref. Page 348 Data Communications and Computer Networks Slide 29/36

30. Bridges • Operate at bottom two layers of the OSI model • Connect networks that use the same communication protocols protocols above data-link layer but may use different at physical and data-link layers Ref. Page 349 Data Communications and Computer Networks Slide 30/36

31. Routers • Operates at network layer of the OSI model • Used to interconnect those networks that use the same high-level protocols above network layer • Smarter than bridges as they not only copy data from one network segment to another, but also choose the best route for the data by using routing table Ref. Page 349 Data Communications and Computer Networks Slide 31/36

32. Gateways • Operates at the top three layers of the OSI model (session, presentation and application) • Used for interconnecting dissimilar networks that use different communication protocols • Since gateways interconnect dissimilar networks, protocol them conversion is the major job performed by Ref. Page 349 Data Communications and Computer Networks Slide 32/36

33. Wireless Computing Systems • Wireless computing system uses wireless communication technologies for interconnecting computer systems • Enhances functionality of computing equipment by freeing communication from location constraints of wired computing systems • Wireless computing systems are of two types: Fixed wireless systems: Support little or no mobility of the computing equipment associated with the wireless network Mobile wireless systems: Support mobility of the computing equipment to access resources associated with the wireless network • • Ref. Page 349 Data Communications and Computer Networks Slide 33/36

34. Wireless Technologies • 2G and 3G • Wireless LAN • WiMAX • Wireless Local Loop (WLL) • Radio-router • Multihop • Wireless Wireless Network Application Protocol (WAP) Ref. Page 351 Data Communications and Computer Networks Slide 34/36

35. Distributed Computing Systems Configuration where many independent computer • systems are connected, and messages, processing task, programs, data, and other resources are transmitted between cooperating computer systems Such an arrangement enables sharing of many • hardware and software resources as well as information among several users who may be sitting far away from each other Ref. Page 352 Data Communications and Computer Networks Slide 35/36

36. Main Advantages of Distributed Computing Systems • Inherently distributed applications • Information sharing among distributed users • Resource sharing • Shorter response times and higher throughput • Higher reliability • Extensibility and incremental growth • Better flexibility in meeting users’ needs Ref. Page 353 Data Communications and Computer Networks Slide 36/36

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