Computer Network :: Network Basic

1. Chapter Three
3.1 Network Basic
3.1.1 Basic Concept of Network
At the end of this topic, students
should be able to:
Explain the concept of network

2. What to cover?
• Definition of network
• Communication device
• Transmission media
• Advantages and disadvantages of network

3. What is a network?
A network is a worldwide collection of networks
that connects millions of businesses,
educational institutions and individuals.
(Shelly, 2016)
Pages 470 - 471
Discovering Computers : Chapter 9

4. What is a network?
A network is basically a wired or wireless
network that connects together a group of
computing resources such as computers,
printers and servers, which are located at
different places.
(Yew ,Low, 2014)
Pages 470 - 471
Discovering Computers : Chapter 9

5. Discovering Computers : Chapter 9
Pages 460

6. Communication System
Sending
device
Receiving
device
Comm.
device
Communication
channel /
Transmission media
Comm.
device

7. Communications System
• A sending device that initiates an instruction to
transmit data, instructions, or information.
• A communications device that connects the sending
device to a communications channel.
• A communications channel, or transmission media on
which the data, instructions, or information travel.
• A communications device that connects the
communications channel to a receiving device.
• A receiving device that accepts the transmission of
data, instructions, or information.

8. Communication Devices
Hardware or equipment which are designed to transfer
signals or data from a sender to receiver.
Example: Hub, switch, modem, router, repeater, access
point, network interface card (NIC).

9. Transmission Media
Transmission media consist of materials or substances
capable of carrying one or more signals.
(Shelly, 2012)
• A communications channel, or transmission media on
which the data, instructions, or information travel.

10. Types of Transmission Media
1. Wired transmission media
The transmission of signals or data by means of wire,
cable, or other physical connections (transmitter) between
a sender and a receiver.
Example: Fiber-optic cable, Cable television(coaxial cable),
Internet access(broadband media) and telephone
networks(twisted-pair cable)

11. Types of Transmission Media
2. Wireless transmission media
The signals or data are transferred between a sender to a
receiver by means of radio (electromagnetic) waves.
The sender and receiver are not connected by any
electrical or optical wires/cables.
Example : cellular radio, satellite, broadcast radio,
microwaves, Bluetooth, infrared.

12. Advantages of Using a Network?
Facilitating
communications
Sharing
hardware
Sharing data
and information
Sharing
software
Transferring
funds

13. facilitating communications
Using a network, people communicate efficiently and easily via e-mail,
instant messaging, chat rooms, blogs, wikis, online social networks, video
telephone calls, online meetings, video conferencing, VoIP, wireless
messaging services, and groupware.
Sharing hardware
In a networked environment, each computer on the network can have
access to all hardware on the network.
sharing data and information
In a networked environment, any authorized computer user can access
data and information stored on other computers on the network.
sharing software
Users connected to a network have access to software on the network.
transferring funds
Called electronic funds transfer (EFT ), it allows users connected to a
network to transfer money from one bank account to another via
transmission media.

14. Discovering Computers : Chapter 9• Page 470
• Figure 9-9

15. • Viruses
When computers are connected by a network, the virus can spread itself
electronically, at computer speeds.
• Network failure
If the file server fails then no-one on the network can access any files or folders.
This means that nobody can do any work. For an organisation, this would be
extremely costly and disruptive.
• Slow service
As more users log onto the network and request files, send things to be printed
and open more software applications, the network can start to slow down.
• Cost
Every workstation needs a network interface card to enable it to be connected to
the network. Other hardware such as hubs, switches and routers are often
needed.
• Expert support required
Networks need constant monitoring to ensure that the performance is maintained
and that all of the components are working properly. This requires specialist staff
such as network managers and technicians who will spend all of their time
ensuring that the network works efficiently whenever you need to use it. These
staff add a large cost to running a network, but without them, things would start
to fail.
Disadvantages of Using a Network?

16. Chapter Three
3.1 Network Basic
3.1.2 Network Architecture
At the end of this topic, students
should be able to:
Explain types of network
architecture

17. What to cover?
Type of network architecture
• Peer-to-peer
• Client/Server
Differentiate between
client/server and peer-to-peer
networks, and describe how a
peer-to-peer network works

18. Network Architecture
• The design of computers, devices, and media on a
network is sometimes called the network architecture
Discovering Computers : Chapter 9 18Pages 473 – 474
Figures 9-13 – 9-14
Client/server network Peer-to-peer network

19. Peer-to-Peer
• Each computer, called a peer, has equal
responsibilities and capabilities , sharing hardware
(such as a printer), data and information with
other computers.
Discovering Computers : Chapter 9 19Page 475
Figure 9-15
Peer-to-peer network

20. Client-Server
One or more computers act as a server, and
the other computers on the network request
services from the server.
Discovering Computers : Chapter 9 20Page 475
Figure 9-15

21. Client
clients are other computers and mobile devices
on the network that rely on the server for its
resources.
Server
server, sometimes called a host computer,
controls access to the hardware, software, and
other resources on the network and provides
a centralized storage area for programs, data,
and information.

22. Peer-to-peer versus client-server
Num Peer-to-peer Client-server
1. Every user is taking
care of his/her own
machine so could be
difficult to administer
the network
Centralized control by the
server can be more efficient at
administering the whole
network.
2. Easy to install and
configure for the
computers in the
network.
Network professionals are
normally needed to manage
and maintain the whole
network.
3. Cost to install and
maintain network is
inexpensive.
Cost to install and manage the
network can be expensive.
4. Each computer has
equal responsibilities
and capabilities.
Only servers have high
responsibilities and
capabilities.

23. Chapter Three
3.1 Network Basic
3.1.3 Network Topology
At the end of this topic, students
should be able to:
Explain types of network topology

24. Networks
• A network topology refers to the layout of the nodes
(computers and devices) in a communications network
Discovering Computers : Chapter 9 24Pages 475 – 477
Figures 9-16 – 9-18
Star network Bus network Ring network

25. A network topology refers to the layout of
the computers and devices in a
communications network.
It refers to both the physical and logical
layout of a network.
What Is a Topology?

26. Physical Topology
The arrangement of a cabling is the physical
topology.
Logical Topology
The path that data travels between computers
on a network is the logical topology.
Layout of Network

27. Types of network topology.
Three commonly used network topologies are:
Bus network
Star network
Ring network

28. Diagram of different network topologies.
Ring
Star
Bus

29. Bus Network Topology
A bus network consists of a single central
cable (backbone), to which all computers and
other devices connect.
T-Connector
Terminator
BackboneT-Connector
Nodes

30. Each devices is connected to the single central
cable(backbone) through T-Connector.
A terminator is required at each end of the bus
cable to prevent the signal from bouncing back
and forth on the bus cable.
T-Connector
Terminator
Backbone
Bus Network Topology

31. transmit data, instructions, and information
as a series of signal.
Those signals are sent as electrical pulses that
travel along the length of the cable in all directions.
Bus Network Topology

32. When a sending device transmits data, the
address of the receiving device is included
with the transmission.
If the device address does not match the
intended address for the data, the device
ignores the data.
If the data does match the device address, the
data is accepted.
All devices receive the data but only the
receiving device accept them.
Bus Network Topology

33. Advantages:
1. Bus networks are inexpensive and easy to install.
So popular on Local Area Network (LAN).
2. Computers and other devices can be attached
and detached at any point on the bus without
disturbing the rest of the network.
3. Failure of one device usually does not affect the
rest of the bus network.
Bus Network Topology

34. Disadvantages:
1. There might be disruption when computer or
other devices are added or removed.
2. Because all systems on the network connect to
a single cable or backbone, a break in the cable
will prevent all systems from accessing the
network.
3. It is difficult to identify the problem if the entire
network shut down.
Bus Network Topology

35. Star Network Topology
All the computers and other devices on the
network connect to a central device, thus forming
a star.

36. Two types of devices that provide a common
central connection point to all the other devices
on the network are a hub and a switch.
Hub / Switch
Star Network Topology

37. The device that provides a common central
connection point for other devices on a
network.
All data that transfers from one device to
another passes through the hub or switch.
The hub takes a signal that comes from any
device and passes it along to all the other
devices in the network.
Hub / Switch
Hub / Switch
Star Network Topology

38. Advantages:
1. If one device fails, only that device is affected.
2. Devices can be added to or removed from
network with little or no disruption.
3. Easy to troubleshoot and isolate problem.
Star Network Topology

39. Disadvantages:
1. If the hub or switch fails, the entire network will
be inoperabled.
2. Requires more cable than most of the other
topologies.
3. More expensive because of the cost of the
hub/switch.
Star Network Topology

40. Ring Network Topology
On a ring network, a cable forms a closed loop
(ring) with all computers and devices arranged
along the ring.

41. Data transmitted on a ring network travels from
device to device around the entire ring, in one
direction (clockwise or counterclockwise)
Token passing is one method for sending data
around a ring
Each device takes a turn sending and receiving
information through the
use of a token.
Ring Network Topology

42. The token along with any data is sent from the
first device to the second device which extracts the
data addressed to it and adds any data it wishes
to send.
Then second device passes the token and data to
the third device, etc. until it comes back around to
the first device again.
Only the device with the token is allowed to send
data . All other devices must wait for the token to
come to them.
Ring Network Topology

43. Ring Network Topology

44. Advantages:
1. The transmission of data is relatively
simple as packets travel in one direction only.
2. Cable faults are easily located, making
troubleshooting easier.
3. The uses of token passing enables all devices in
a ring topology to share the network resources
fairly.
Ring Network Topology

45. Disadvantages:
1. A failure in any cable or device breaks the
loop and can take down the entire network.
2. Data packets must pass through every computer
therefore, this makes it slower.
3. A ring network can span a larger distance than a
bus network, but it is more difficult to install.
Ring Network Topology

46. DEFINITION ADVANTAGES DISADVANTAGES
A bus network
consists of a
single central
cable (backbone),
to which all
computers and
other devices
connect.
Inexpensive and
easy to install.
There might be
disruption when
computer or other
devices are added
or removed.
Other devices ca be
attached or detached
without disturbing
the network.
Failure of one device
usually does not
affect the rest
of the network.
The break in the
main cable(backbone)
will prevent all systems
from accessing the
network.
It is difficult to
identify the problem
if the entire network
Shut down.
Summary:
BUS NETWORK TOPOLOGY

47. DEFINITION ADVANTAGES DISADVANTAGES
All the computers
and other devices
on the network
connect to a
central device,
thus forming a
star.
If one device fails,
only that device
is affected.
If the hub or switch
fails, the entire
network will be
inoperabled.
Devices can be added
or removed from
network with no
disruption.
Easy to
troubleshoot and
isolate problem.
Requires more cables
than most of the
other topologies.
More expensive
because of the
cost of hub/switch.
Summary:
STAR NETWORK TOPOLOGY

48. Summary:
DEFINITION ADVANTAGES DISADVANTAGES
On a ring network,
a cable forms a
closed loop (ring)
with all computers
and devices
arranged
along the ring.
Transmission of data
is simple as packets
travel in one
direction only.
A failure in any cable
or device breaks the
loop and can take
down entire
network.
Cabel faults are easily
located, making
troubleshooting
easier.
All devices in ring
topolgy share the
network resources
fairly.
Data packets must
pass through every
computer, thus make
it slower.
More difficult to
install than a
bus network.
RING NETWORK TOPOLOGY

49. Chapter Three
3.1 Network Basic
3.1.4 Classification of Network
At the end of this topic, students
should be able to:
Differentiate among Local Area
Network (LAN), Metropolitan Area
Network (MAN) and Wide Area
Network (WAN)

50. Networks typically are classified as:
a) LOCAL AREA NETWORK
• Definition
• Types of LAN:
– Personal area network (PAN)
– Home area network (HAN)
• Advantages and Disadvantages of LAN
b) METROPOLITAN AREA NETWORK
• Definition
• Type of MAN
– Campus network
• Advantages and Disadvantages of MAN
c) WIDE AREA NETWORK
• Definition
• Types of WAN
– Enterprise private network
– Virtual private network
• Advantages and Disadvantages of WAN

51. MAN
LAN
LAN LAN
MAN
LAN
LAN LAN
MAN
LAN
LAN LAN

52. LOCAL AREA NETWORK

53. • A local area network
(LAN) is a network
that connects
computers and
devices in a limited
geographical area
• A wireless LAN
(WLAN) is a LAN that
uses no physical
wires
Discovering Computers : Chapter 9
53• Page 472
• Figures 9-10 – 9-11

54. • Normally used bus
network.
Discovering Computers : Chapter 9
54• Page 472
• Figures 9-10 – 9-11

55. Advantages
• Easy to share devices
(printers, scanners, external drives)
• Easy to share data
(homework, pictures)
• Cost of LAN Setup is low.
LOCAL AREA NETWORK

56. Disadvantages
• Power - a good LAN is required to be ‘ON’
all the times.
• Security - each computer and device
become another point of entry for
undesirables.
• if all computers running at once, can reduce
speed for each.
• Area covered is limited
LOCAL AREA NETWORK

57. METROPOLITAN AREA NETWORK

58. • A metropolitan area network (MAN) is a high-
speed network that connects local area networks
in a metropolitan area such as a city or town and
handles the bulk of communications activity
across that region.
Discovering Computers : Chapter 9 58• Page 473
• Figure 9-12

59. Example of a MAN

60. Example of a MAN
• Surveillance System
• Traffic Light Monitoring System
• Cable Network TV

61. Type of MAN
Campus Area Network (CAN)
• A campus network is a computer network
made up of an interconnection of local area
networks (LAN's) within a limited geographical
area.

62. • In the case of a university campus-based
campus network, the network is likely to
link a variety of campus buildings including;
academic departments, the university
library and student residence halls.
Type of MAN
Campus Area Network (CAN)

63. Example:
Campus Area Network (CAN)
Academic Departments
University
Library
Student
Residence Halls.

64. Advantages
• efficiency and shared access.
• All the computer-owning residents of the
area have equal ability to go on line.
METROPOLITAN AREA NETWORK

65. Disadvantages
• it can be costly
(hardware, software, support, etc.).
• security problems
• As the network consists of many computers
over the span of a city, the connection can
lag or become quite slow.
METROPOLITAN AREA NETWORK

66. WIDE AREA NETWORK

67. A wide area network (WAN) is a network that
covers a large geographic area (such as a city,
country, or the world) using a communications
channel that combines many types of media such
as telephone lines, cables, and radio waves.
The Internet is the world’s largest WAN

68. Advantages
• increased efficiency, ease of
communication, and lowered costs.
WIDE AREA NETWORK

69. Disadvantages
• security problems
• training costs
• maintenance problems. Large enterprises
will dedicate personnel to maintaining their
WAN.
WIDE AREA NETWORK

70. How Are LAN, MAN, and WAN Different?

71. How Are LAN, MAN, and WAN Different?
• The main differentiation among these
classifications is their area of coverage.
LAN, MAN and WAN compared

72. CRITERIA Geographical Area Provider
LAN Connects computers and devices
in a limited geographical area such
as computer laboratory.
No provider
MAN Connects computers and devices
in a metropolitan area such as
town or city.
Single provider
WAN Connects computers and devices
in a large geographical area such
as country, world.
Multi-provider
Comparison:

73. CRITERIA Connectivity Technology
LAN Computers are located
within the same building,
usually connected through
wires.
Ethernet, token
ring, FDDI, Wifi
MAN Computers connected via
telephone lines or
modems, fiber optic, cable
television.
ATM, SMDS,
FDDI
WAN Computers connected via
satellite or Internet.
Circuit
Switched,
Packet Switched
Comparison: