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Overview of Data Communication and Computer Networks

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1 Overview of Data Communication and Computer Networks

2 When we communicate, we are sharing information.
This sharing can be local or remote. Between individuals, local communication usually occurs face to face, while remote communication takes place over distance.

3 The term telecommunication, which includes telephony, telegraphy, and television, means communication at a distance (tele means "far“ in Greek) The effectiveness of a data communications system depends on four fundamental characteristics: delivery, accuracy, timeliness, and jitter.

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

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

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

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

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

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

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

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

12 Types of Connections Point-to-point Multipoint (multidrop)

13 Point-To-Point Connection

14 Multipoint Connection
Wireless

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

16 Point-to-Point Connection

17 Fully Connected Mesh Topology
A D B C

18 Fully Connected Mesh Topology

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

20 Star Topology A D Drop Hub B C Drop

21 Star Topology A D Switch B C

22 Star Topology A D Hub B C

23 Star Topology Pros: Cons: 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

24 Bus Topology Drop line Tap Terminator

25 Bus Topology A B C D

26 Bus Topology

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

28 Ring Topology C D B A

29 Ring Topology

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

31 Hybrid Topologies

32 Networks Network: a set of devices connected by media links Laptop
Printer Workstation Laptop Scanner Server

33 Network Categories Local Area Network (LAN) Wide Area Network (WAN)
Metropolitan Area Network (MAN)

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

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

36 Metropolitan Area Networks
Network extended over an entire city Bangkhen Kampangsaen

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

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

39 Internetworks Two or more networks connected become an internetwork, or internet Example: The Internet Network1 Network2 Gateway Network3

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

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


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