1. 1 Overview of Data Communication and Computer Networks 01204325: Data Communication and Computer Networks Asst. Prof. Chaiporn Jaikaeo, Ph.D. chaiporn.j@ku.ac.th http://www.cpe.ku.ac.th/~cpj Computer Engineering Department Kasetsart University, Bangkok, Thailand

2. 2 Outline Data Communication Overview Data Communication Overview Definition Definition Components Components Protocols and standards Protocols and standards Network Overview Network Overview Connectivity Connectivity Categories Categories Internetworks Internetworks

3. 3 Motivations Efficient way to share resources Efficient way to share resources Cost – less expensive Cost – less expensive Accessibility – easier Accessibility – easier Efficient way to exchange information Efficient way to exchange information Time – faster Time – faster Size – bigger Size – bigger Correctness – more accurate Correctness – more accurate

4. 4 Data Communication: Definition Data Communication: Data Communication: Transfer of data from one device to another via some form of transmission medium. Transfer of data from one device to another via some form of transmission medium.

5. 5 Data Communication Hi, how are you? 01010001 Hi, how are you? Computer you? how are Hi, you? how are Hi, 01010001

6. 6 Components in Communication Hi, how are you? 5Protocol 4Medium 3Receiver 2Sender 1Message

7. 7 Data Representation Numbers Numbers 8/16/32 bit integers 8/16/32 bit integers floating point floating point Text Text ASCII, Unicode ASCII, Unicode Images Images Bit patterns, Graphics formats JPG/GIF/etc Bit patterns, Graphics formats JPG/GIF/etc Audio  Samples of continuous signal Audio  Samples of continuous signal Video  Sequence of bitmap images Video  Sequence of bitmap images 150 2 255

8. 8 Protocols and Standards Protocol Protocol A set of rules governing data communications A set of rules governing data communications Syntax: format of data block Syntax: format of data block Semantics: meaning of each section Semantics: meaning of each section Timing: speed and sequencing Timing: speed and sequencing Standards Standards De facto (in practice) standards De facto (in practice) standards  not approved but widely adopted De jure (in law) standards De jure (in law) standards  approved by an organization

9. 9 Standards Organizations Creation Committees Creation Committees ISO, ITU-T, ANSI, IEEE, EIA ISO, ITU-T, ANSI, IEEE, EIA Forums Forums Regulatory Agencies Regulatory Agencies

10. 10 Direction of Data Flow Simplex: One direction only Simplex: One direction only Server Monitor data flow Keyboard data flow

11. 11 Direction of Data Flow Half Duplex: Both directions, one at a time Half Duplex: Both directions, one at a time E.g., walkie-talkies E.g., walkie-talkies data flow at time 1 data flow at time 2

12. 12 Direction of Data Flow Full Duplex: Both directions simultaneously Full Duplex: Both directions simultaneously E.g., telephone E.g., telephone Can be emulated on a single communication link using various methods Can be emulated on a single communication link using various methods data flow

13. 13 Networks Network: a set of devices connected by media links Network: a set of devices connected by media links Media Links Printer Workstation Laptop Scanner Server

14. 14 Types of Connections Point-to-point Point-to-point Multipoint (multidrop) Multipoint (multidrop)

15. 15 Point-To-Point Connection

16. 16 Multipoint Connection Wireless

17. 17 Topology Topology: physical or logical arrangement of devices Topology: physical or logical arrangement of devices Point-to-point Point-to-point Mesh Mesh Star Star Bus Bus Ring Ring Hybrid Hybrid

18. Point-to-Point Connection 18

19. 19 Fully Connected Mesh Topology A CB D E

20. 20 Fully Connected Mesh Topology

21. 21 Fully Connected Mesh Topology Pros: Dedicated links Robustness Privacy Easy to identify fault Cons: A lot of cabling I/O ports Difficult to move

22. 22 Star Topology Hub A D BC Drop

23. 23 Star Topology Switch A D BC

24. 24 Star Topology Hub A D BC

25. 25 Star Topology Pros: One I/O port per device Little cabling Easy to install Robustness Easy to identify fault Cons: Single point of failure More cabling still required Hub

26. 26 Bus Topology Drop line Tap Terminator

27. 27 Bus Topology A BC D

28. 28 Bus Topology

29. 29 Bus Topology Pros: Little cabling Easy to install Cons: Difficult to modify Difficult to isolate fault Break in the bus cable stops all transmission

30. 30 Ring Topology A B C D

31. 31 Ring Topology

32. 32 Ring Topology Pros: Easy to install Easy to identify fault Cons: Delay in large ring Break in the ring stops all transmission

33. 33 Hybrid Topologies

34. 34 Network Categories Local Area Network (LAN) Local Area Network (LAN) Wide Area Network (WAN) Wide Area Network (WAN) Metropolitan Area Network (MAN) Metropolitan Area Network (MAN)

35. 35 Local Area Networks Network in a single office, building, or campus Network in a single office, building, or campus

36. 36 Wide Area Networks Network providing long-distance communication over a country, a continent, or the whole world Network providing long-distance communication over a country, a continent, or the whole world

37. 37 WAN Technologies Circuit Switching Circuit Switching Physical links are dedicated between two points Physical links are dedicated between two points Packet Switching Packet Switching Data are put in packets which are stored and forwarded at each node Data are put in packets which are stored and forwarded at each node Virtual Circuit Switching Virtual Circuit Switching Virtual links are established between two points Virtual links are established between two points  Frame Relay and ATM (Asynchronous Transfer Mode)

38. 38 Metropolitan Area Networks Network extended over an entire city Network extended over an entire city Bangkhen Kampangsaen

39. 39 Switching Dedicated circuits Dedicated circuits Circuit switching Circuit switching Telephone switches establish circuits for communication Telephone switches establish circuits for communication Packet switching Packet switching Data are put into packets Data are put into packets Each stamped with source and destination addresses Each stamped with source and destination addresses Routers know where to forward packets Routers know where to forward packets telephone switch Router Packet

40. 40 Network of Networks Company A Company D Network Interface Card (NIC) Company B Company C

41. 41 Internetworking How to allow devices from different standards to communicate How to allow devices from different standards to communicate Gateways/routers – devices capable of communicating in several standards Gateways/routers – devices capable of communicating in several standards These become "network of networks" These become "network of networks"

42. 42 Internetworks Two or more networks connected become an internetwork, or internet Two or more networks connected become an internetwork, or internet Example: The Internet Example: The Internet Network1Network2 Gateway Network3

43. 43 The Internet The largest internetwork (network of networks) in the world The largest internetwork (network of networks) in the world Devices communicating with TCP/IP protocol suite Devices communicating with TCP/IP protocol suite UCLAStanford UC Santa Barbara U. of Utah

44. 44 Summary Data communication Data communication Protocols and standards Protocols and standards Computer networks Computer networks Topologies Topologies LAN/MAN/WAN LAN/MAN/WAN Internetworks (networks of networks) Internetworks (networks of networks)