Komunikasi Data dan Jaringan Komputer (Bagian 1)

1. Internet dan Jaringan Komputer Komunikasi Data dan Jaringan Komputer(Bagian 1) Dr. Tb. Maulana Kusuma mkusuma@staff.gunadarma.ac.id http://staffsite.gunadarma.ac.id/mkusuma Magister Manajemen Sistem Informasi

2. Referensi • W. Stallings, Data and Computer Communications, 4ed, Macmillan, 1994. • F. Halsall, Data Communications, Computer Networks and Open Systems, Addison Wesley, 1996. Magister Manajemen Sistem Informasi

3. A Communications Model • Source • generates data to be transmitted • Transmitter • Converts data into transmittable signals • Transmission System • Carries data • Receiver • Converts received signal into data • Destination • Takes incoming data Magister Manajemen Sistem Informasi

4. Simplified Communications Model - Diagram Magister Manajemen Sistem Informasi

5. Simplified Data Communications Model Magister Manajemen Sistem Informasi

6. Key Communications Tasks • Transmission System Utilization • Interfacing • Signal Generation • Synchronization • Exchange Management • Error detection and correction • Addressing and routing • Recovery • Message formatting • Security • Network Management Magister Manajemen Sistem Informasi

7. Communications Standard • Many types of connection media : telephone lines, optical fibers, cables, radios, etc. • Many different types of machines and operating systems • Many different network applications Magister Manajemen Sistem Informasi

8. What “Standard” means? • How many volts pulse is a 0 and 1 ? • How to determine the end of a message ? • How to handle lost messages ? • How many bits for different data types ? Integers/Strings, etc.; are ASCII chars ? • How machines are identified ? • How to find the way to reach a machine ? • How applications speaks together through the network ? Magister Manajemen Sistem Informasi

9. Standard Bodies • International Telecommunications Union – Telecommunications Sector (ITU-T) • Institute of Electrical and Electronics Engineers (IEEE) • International Organization for Standardization (ISO) • Electronic Industries Alliance (EIA) • dll Magister Manajemen Sistem Informasi

10. The ISO/OSI Model ISO (the International Standards Organization) has developed a reference model for communications, called the OSI (Open Systems Interconnection) OPEN SYSTEM means that it can communicate with any other system that follows the specified standards, formats and semantics. Magister Manajemen Sistem Informasi

11. Program X Data Program Y AH Data Application Application Presentation PH Dataunit Presentation Session SH Data unit Session Transport TH Data unit Transport Network NH Data unit Network Data link LH Data unit LT Data link Physical Bits Physical Physical transmission medium OSI Networking Model Magister Manajemen Sistem Informasi

12. OSI Layers (1) • Physical • Physical interface between devices • Mechanical • Electrical • Functional • Procedural • Data Link • Means of activating, maintaining and deactivating a reliable link • Error detection and control • Higher layers may assume error free transmission Magister Manajemen Sistem Informasi

13. OSI Layers (2) • Network • Transport of information • Higher layers do not need to know about underlying technology • Not needed on direct links • Transport • Exchange of data between end systems • Error free • In sequence • No losses • No duplicates • Quality of service Magister Manajemen Sistem Informasi

14. OSI Layers (3) • Session • Control of dialogues between applications • Dialogue discipline • Grouping • Recovery • Presentation • Data formats and coding • Data compression • Encryption • Application • Means for applications to access OSI environment Magister Manajemen Sistem Informasi

15. Transmission Medium • Guided - wire • Unguided - wireless • Characteristics and quality determined by medium and signal • For guided, the medium is more important • For unguided, the bandwidth produced by the antenna is more important • Key concerns are data rate and distance Magister Manajemen Sistem Informasi

16. Guided Transmission Media • Twisted Pair • Coaxial cable • Optical fiber Magister Manajemen Sistem Informasi

17. Twisted Pair • Twisted pair - INEXPENSIVE • Two wires twisted together. • Makes them less susceptible to acting like an antenna and picking up radio frequency information or appliance noise. • Telephone company uses twisted-pair copper wires to link telephones. Magister Manajemen Sistem Informasi

18. Twisted Pair Magister Manajemen Sistem Informasi

19. Twisted Pair - Applications • Most common medium • Telephone network • Between house and local exchange (subscriber loop) • Within buildings • To private branch exchange (PBX) • For local area networks (LAN) • 10Mbps or 100Mbps Magister Manajemen Sistem Informasi

20. Twisted Pair - Pros and Cons • Cheap • Easy to work with • Low data rate • Short range Magister Manajemen Sistem Informasi

21. Twisted Pair - Transmission Characteristics • Analog • Amplifiers every 5km to 6km • Digital • Use either analog or digital signals • repeater every 2km or 3km • Limited distance • Limited bandwidth (1MHz) • Limited data rate (100MHz) • Susceptible to interference and noise Magister Manajemen Sistem Informasi

22. Unshielded and Shielded TP • Unshielded Twisted Pair (UTP) • Ordinary telephone wire • Cheapest • Easiest to install • Suffers from external EM interference • Shielded Twisted Pair (STP) • Metal braid or sheathing that reduces interference • More expensive • Harder to handle (thick, heavy) Magister Manajemen Sistem Informasi

23. UTP Categories • Cat 3 • up to 16MHz • Voice grade found in most offices • Twist length of 7.5 cm to 10 cm • Cat 4 • up to 20 MHz • Cat 5 or Cat 6 • up to 100MHz • Commonly pre-installed in new office buildings • Twist length 0.6 cm to 0.85 cm Magister Manajemen Sistem Informasi

24. Coaxial Cable (1) • Coaxial cable • Also two wires: • One of the wires is woven of fine strands of copper forming a tube. • The wire mesh surrounds a solid copper wire that runs down the center. • Space between has a non-conducting material. • Makes them more impervious to outside noise. Use this when 1. Long distances 2. Lots of interference Magister Manajemen Sistem Informasi

25. Coaxial Cable (2) Magister Manajemen Sistem Informasi

26. Coaxial Cable (3) Magister Manajemen Sistem Informasi

27. Coaxial Cable Applications • Most versatile medium • Television distribution • Aerial to TV • Cable TV • Long distance telephone transmission • Can carry 10,000 voice calls simultaneously • Being replaced by fiber optic • Short distance computer systems links • Local area networks Magister Manajemen Sistem Informasi

28. Coaxial Cable - Transmission Characteristics • Analog • Amplifiers every few km • Closer if higher frequency • Up to 500MHz • Digital • Repeater every 1km • Closer for higher data rates Magister Manajemen Sistem Informasi

29. Optical Fiber (1) Magister Manajemen Sistem Informasi

30. Optical Fiber (2) Magister Manajemen Sistem Informasi

31. Optical Fiber (3) • Fiber-optic cable • (BIG JOBS + EXPENSIVE) • Light is electromagnetic. • Can transmit more information down a single strand. • It can send a wider set of frequencies. • Each cable can send several thousand phone conversations or computer communications. Magister Manajemen Sistem Informasi

32. Optical Fiber - Spectrum Magister Manajemen Sistem Informasi

33. Optical Fiber - Benefits • Greater capacity • Data rates of hundreds of Gbps • Smaller size & weight • Lower attenuation • Electromagnetic isolation • Greater repeater spacing • 10s of km at least Magister Manajemen Sistem Informasi

34. Optical Fiber - Applications • Long-haul trunks • Metropolitan trunks • Rural exchange trunks • Subscriber loops • LANs Magister Manajemen Sistem Informasi

35. Optical Fiber - Transmission Characteristics • Act as wave guide for 1014 to 1015 Hz • Portions of infrared and visible spectrum • Light Emitting Diode (LED) • Cheaper • Wider operating temp range • Last longer • Injection Laser Diode (ILD) • More efficient • Greater data rate • Wavelength Division Multiplexing (WDM) Magister Manajemen Sistem Informasi

36. Optical Fiber Transmission Modes Magister Manajemen Sistem Informasi

37. Wireless Transmission • Unguided media • Transmission and reception via antenna • Directional • Focused beam • Careful alignment required • Omni-directional • Signal spreads in all directions • Can be received by many antenna Magister Manajemen Sistem Informasi

38. Frequencies • 2GHz to 40GHz • Microwave • Highly directional • Point to point • Satellite • 30MHz to 1GHz • Omni-directional • Broadcast radio • 3 x 1011 to 2 x 1014 • Infrared • Local Magister Manajemen Sistem Informasi

39. Terrestrial Microwave • Parabolic dish • Focused beam • Line of sight • Long haul telecommunications • Higher frequencies give higher data rates Magister Manajemen Sistem Informasi

40. Satellite Microwave • Satellite is relay station • Satellite receives on one frequency, amplifies or repeats signal and transmits on another frequency • Requires geo-stationary orbit • Height of ±35,784km • Television • Long distance telephone • Private business networks Magister Manajemen Sistem Informasi

41. Broadcast Radio • Omni-directional • FM radio • UHF and VHF television • Line of sight • Suffers from multi-path interference Magister Manajemen Sistem Informasi

42. Infrared • Modulate non-coherent infrared light • Line of sight (or reflection) • Blocked by walls • e.g. TV remote control, IRD port Magister Manajemen Sistem Informasi

43. Terminology (1) • Transmitter • Receiver • Medium • Guided medium • e.g. twisted pair, optical fiber • Unguided medium • e.g. air, water, vacuum Magister Manajemen Sistem Informasi

44. Terminology (2) • Direct link • No intermediate devices • Point-to-point • Direct link • Only 2 devices share link • Multi-point • More than two devices share the link Magister Manajemen Sistem Informasi

45. Terminology (3) • Simplex • One direction • e.g. Television • Half duplex • Either direction, but only one way at a time • e.g. police radio • Full duplex • Both directions at the same time • e.g. telephone Magister Manajemen Sistem Informasi

46. Terminology (4) • Bits per second (bps). • The number of bits (0’s and 1’s) that travel down the channel per second. • Baud rate • The number of bits that travel down the channel in a given interval. • The number is given in signal changes per second, not necessarily bits per second. Magister Manajemen Sistem Informasi

47. Terminology (5) • Asynchronous transmission • Information is sent byte by byte. • Cheaper and more commonly used. • Synchronous transmission • Data is sent in large blocks rather than in small pieces. • Preceded by special information, concerning error detection and block size. • These modems are expensive but very fast. Magister Manajemen Sistem Informasi

48. Analog and Digital Data Transmission • Data • Entities that convey meaning • Signals • Electric or electromagnetic representations of data • Transmission • Communication of data by propagation and processing of signals Magister Manajemen Sistem Informasi

49. Data • Analog • Continuous values within some interval • e.g. sound, video • Digital • Discrete values • e.g. text, integers Magister Manajemen Sistem Informasi

50. Data and Signals • Usually use digital signals for digital data and analog signals for analog data • Can use analog signal to carry digital data • Modem • Can use digital signal to carry analog data • Compact Disc audio Magister Manajemen Sistem Informasi