1. NETWORKS

2. CONTENT DATA TRANSMISSION HARDWARE TRANSMISSION MEDIA
DEFINITION
DATA TRANSMISSION
HARDWARE
TRANSMISSION MEDIA
TYPES OF NETWORKS
TOPOLOGIES
EVALUATION

3. WHAT IS A NETWORK
A computer network, or simply a network, is a collection of computers and other hardware interconnected by communication channels that allow sharing of resources and information

4. DATA TRANSMISSION
Bandwidth describes how much data can be transmitted at a time. The greater the bandwidth, the faster the information can flow. The speed of transmission is measured in baud.
The types of bandwidth are:
Narrowband transmission
Voice band transmission
Broadband transmission

5. NARROWBAND
A small bandwidth that can transmit only 10 – 30 characters per second. Used for telegraphy. (Not used anymore)

6. VOICE BAND
Can transmit about 1000 – 8000 characters per second. It is used on telephone lines.

7. BROADBAND
Allows up to hundreds of thousands of characters to be transmitted per second

8. TRANSMISSION MODES There are three data transmission modes Simplex
Half duplex
(Full) Duplex

9. SIMPLEX
Data is transmitted in one direction only. Example a television

10. HALF DUPLEX
Data is sent and received but not at the same time. Example a walkie talkie.

11. (FULL) DUPLEX
Data is sent and received at the same time. Example a telephone

12. HARDWARE IN A NETWORK
COMPUTER TERMINALS
This is the computer from which users will perform tasks

13. HARDWARE IN A NETWORK HUB
This device allows data to be communicated between hardware devices in a network. It is used in small networks only

14. HARDWARE IN A NETWORK SWITCH
It is the same as a hub but more intelligent. It also directs the flow of traffic between devices. It is used on larger networks

15. HARDWARE IN A NETWORK ROUTER
This device moves data between different networks

16. HARDWARE IN A NETWORK SERVER
This is a computer whose purpose is to ‘serve’ the needs of users on a network. According to the need, a server may be a file server, a mail server, a print server, a web server

17. TRANSMISSION MEDIA Data must be transmitted using some medium.
Media used to transmit data can be:
Wired (cable)
Wireless

18. WIRED MEDIA Twisted Pair Cable
A cheap form of cabling used in small networks.
Advantage:
Inexpensive
Thin and Flexible
Cross talk is minimized
Disadvantage:
Susceptible to electromagnetic interference
Not suitable for sending video

19. TWISTED PAIR CABLE

20. WIRED MEDIA Coaxial Cable
Cabling used in networks but better suited for transmitting audio sounds.
It is used now for connecting television cable receivers.
Advantage:
Suitable for short distances
Inexpensive
Supports multiple channels
Disadvantage:
Noisy
High Installation cost

21. COAXIAL CABLE

22. WIRED MEDIA Fiber Optic
Fiber-optic is a cable used to transmit information from one place to another by sending pulses of light through an optical fiber.
Advantages
Good bandwidth and capacity
Immunity to electrical noise
Disadvantages:
Expensive
Not widely available

23. OPTICAL FIBRE

24. WIRELESS MEDIA Communication Satellites
Also called comsat is an artificial satellite sent to space for the purpose of telecommunications. provide a microwave radio relay technology complementary to that of communication cables. They are also used for mobile applications such as communications to ships, vehicles, planes and hand-held terminals, and for TV and radio broadcasting

25. COMMUNICATION SATELLITES

26. WIRELESS MEDIA Infrared
This is used in short-range communication among computer peripherals and other devices. Devices use infrared light-emitting diodes (LEDs) to emit infrared radiation. The beam is switched on and off, to encode the data. The receiver converts the infrared radiation to an electric current. Infrared communications are useful for indoor use in areas of high population density. It does not penetrate walls and so does not interfere with other devices in adjoining rooms. Infrared is the most common way for remote controls to command appliances

27. INFRARED

28. WIRELESS MEDIA Bluetooth
This is a wireless technology standard for exchanging data over short distances using short-wavelength radio transmissions from fixed and mobile devices, creating personal area networks (PANs) with high levels of security.
USES:
Wireless Bluetooth headset and Intercom
For input and output devices such as wireless mouse and keyboard.

29. BLUETOOTH

30. WIRELESS MEDIA Wi-Fi
Wi-Fi is a popular technology that allows an electronic device to exchange data wirelessly (using radio waves) over a computer network, including high-speed Internet connections. Devices like PC’s smartphone, tablet and game consoles use Wi-Fi to connect to a network or the Internet via a wireless network access point or a hotspot.

31. Wi-Fi

32. TOPOLOGY
Topology refers to the layout of connected devices. This article introduces the standard topologies of networking.
TYPES OF TOPOLOGIES
Bus
Star
Token Ring
Mesh
Tree

33. BUS
 Bus network topology is a network architecture in which a set of clients are connected via a shared communications line/cables, called a bus.

34. STAR
 Star topology every node (computer workstation or any other peripheral) is connected to central node called hub or switch. The switch is the server and the peripherals are the clients

35. TOKEN RING
Stations on a token ring LAN are logically organized in a ring topology with data being transmitted sequentially from one ring station to the next with a control token circulating around the ring controlling access.

36. MESH
Mesh networking is a type of networking where each node must not only capture and send its own data, but also serve as a relay for other nodes, that is, it must work with others to send the data in the network.

37. TREE
This is a combination of the bus and the Star Topology. The tree like structure allows you to have many servers on the network and you can branch out the network in many ways.

38. TYPES OF NETWORKS
LAN
MAN
WAN
INTERNET
INTRANET
EXTRANET

39. LAN Local Area Network
A computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building using network media.

40. Example

41. MAN Metropolitan Area Network
This is a computer network that usually spans a city or a large campus. A MAN usually interconnects a number of local area networks (LANs) using a high-capacity backbone technology, such as fiber-optical links.

42. Example 1

43. Example 2

44. WAN Wide Area Network
This is a network that covers a broad area (i.e., any telecommunications network that links across metropolitan, regional, or national boundaries) using private or public network transports

45. Examples

46. COMPARISONS

47. COMPARISONS

48. INTERNET
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite (often called TCP/IP.) to serve billions of users worldwide

49. Example

50. INTRANET
An intranet is a private computer network that uses Internet Protocol technology to share information, operational systems, or computing services within an organization

51. EXTRANET
This is a computer network that is similar to an intranet but allows controlled access from the outside, for specific business or educational purposes. It extends access to users outside the organization, usually partners, vendors, and suppliers, in isolation from all other Internet users.

52. COMPARISON

53. COMPARISON 2

54. EVALUATION

55. Question 1 Question 2 Question 3 Question 4 Question 5 Question 6

56. Question 1: Which bandwidth can be used for Internet connection?

57. Question 2 What transmission mode does a pager use?

58. Question 3 Which of the three networking devices is the most intelligent? a. Hub b. Router C. Switch

59. Question 4 Which wired media has a copper interior?

60. Question 5 A private network that uses Internet Protocol

61. Question 6 A private network that allows authorized outsiders to access its network.

62. BROADBAND TRANSMISSION

63. SIMPLEX

64. SWITCH

65. COAXIAL CABLE

66. INTRANET

67. EXTRANET