The document provides information about computer networks and networking devices. It begins with definitions of networks and their benefits, including resource sharing, file sharing, and communication. It then discusses different types of networks classified by size (LAN, WAN), structure (client-server, peer-to-peer), and topology (bus, star, ring). Various networking devices are also defined, such as hubs, switches, routers, bridges, firewalls, and wireless access points. The document concludes with examples and diagrams to illustrate key network concepts.

1. L E C T U R E 8
J a n u a r y , 2 0 1 8
IT in Business - I

2. Computer
Networks
IT IN BUSINESS 1

3. 1. Definition and benefits of networks

2. Network Types
3. Network devices

4. Networks Definition

5. Network Technologies Examples
Software
Email, instant messaging, teleconferencing
Hardware
NIC(network interface card) / Modem
Media
Wired / Wireless

6. Networks
In absence of networks….
PC 1
PC 2
PC 3
Data
Sharing

7. Networks
Networking devices ….
PC 1
PC 2
PC 3
Resource
sharing +
Communication

8. Benefits of networks

9. Benefits Of Networks
Resource Sharing:
Network-connected peripheral devices can be shared between multiple users.
1. Printers
2. Scanners
Saves money !!
Hardware Sharing

10. Benefits Of Networks
File sharing:
Files can be stored on a central computer (the file server) allowing data to be
shared throughout an organization.
Authorized users are allowed to share the files on the network.
Beneficial for large organizations to maintain their data in an organized
manner and facilitate access to desired people.

11. Benefits Of Networks
Personal Communications :
Teleconferencing: multi-way communication carried out in real-time using computer networks and other equipment
 Video Conferencing: virtual presence
Camera , microphone , loudspeaker, monitors, CODEC.
 Audio Conferencing: communication between groups of people
Sensitive microphones and echo cancellation software
 Data Conferencing: Shared workspace for participants
Whiteboards : Participants at different locations simultaneously write and draw on an on-screen notepad viewed by everyone.
Example: emails, instant messaging, VoIP

12. Benefits Of Networks
Simultaneous Access:
In organizations, several users may need to access same data at the same
time.
E.g.: Sales report that may be updated by several managers.
In case of modification data may become inconsistent.
Network server can store data that requires simultaneous access.

13. Benefits Of Networks
Simultaneous Access:
Software Programs:
Same programs can be used by many people in an organization.
Non-networked environment: Separate copies of programs are needed.
Expensive and time consuming.
Networked Environment:
1. Site License (Single application copy is bought + license to copy) => less costly as compared to individual
licenses.
1. Network Versions: one copy of application program running on central server. Only necessary files are copied
to individual user’s PC.

14. Benefits Of Networks
Backup:
In organizations, sensitive data must have a backup.
Shared central storage device can be used by users.
Regular backups of data on shared storage device can be created by network
manager.

15. Types Of networks

16. Network Types
Networks can be classified in different ways
1. Based on network size : LAN and WAN
2. Based on management method & structure: Peer-to-peer and
Client/Server
3. Based on topology (connectivity): Bus, Star, Ring …
4. Based on transmission media: Wired and Wireless

17. Networks Types w.r.t Size
Two major types:
 LAN (Local area network)
 WAN(Wide area network)

18. LAN
 Connects computers and devices in a small geographical area.
 Devices are connected via cables or wireless medium.
 Two to hundreds of computers.
E.g.: Computers within a single building i.e. home, school, office

19. LAN
 Different types of devices can be connected…

20. WAN
 Wide area networks
 Connect devices across a wide geographical area.
 Can be a combination of multiple LAN’s.
 Less data transfer rate as compared to LAN.

Example: Bank

21. Concept Check!!A network connecting the local and overseas offices of a
Software house would be an example of a LAN or a WAN?
Can you name the largest network??

22. LAN vs. WAN

23. TYPES w.r.t Size
HYBRID NETWORKS

24. Networks Types w.r.t Size
Hybrid Networks:
 CAN (Campus area network)
 MAN (Metropolitan area network)
 HAN (Home area network)
 PAN (Personal area network)

25. CAN
 Campus area network
 Larger than LAN.
 Multiple departments LAN’s can be connected.
 E.g.: college campus, military base, industrial complex

26. MAN
 Metropolitan area network
 Larger than a large LAN but smaller than a WAN.
 Very high-speed connections. ( fiber optical cable.)
 Used to connect cities and towns.

27. MAN
Example: A network used by a
company whose headquarter is based
in Islamabad while warehouse, factory,
regional offices are situated in different
regions of Rawalpindi.

28. HAN
 Home area network (small scale network)
 Residential LAN
 A network contained within a user's home that connects digital devices
i.e. computers, tablets and their peripheral devices to telephones, TV,
home security systems, home lighting, smart appliances.

29. PAN
 Very small scale network.
 Cell phones, PC, PDA, mp3 players.
 Organized around an individual person.
 E.g.: Bluetooth

30. (Geographical Scope)Classification
• Can you classify networks on
the basis of their decreasing
geographical scope ?
Decreasing
Scope

31. Intranets and Extranets
 Intranet is a private network.
 Companies internal version of internet that is insulated from the global internet.
 Allows access to corporate websites.
 Employees can create web pages on their local computers which can be viewed by other members of same
network.
 Employee can allow other employees to browse their website, upload/download files, audio, video clips.
 Accessible from within the organization.
Makes it easier to communicate and share documents within the company!!

32. Intranets and Extranets
 Extranet is an intranet that is partially available to authorized users outside
organization.
 Team members can share information and data among particular external
parties.
 These external parties could be customers, suppliers, clients.
 Private communication, collaboration, as well as knowledge and document
sharing
Both intranet and extranet serve as communication tools for easy
information sharing for any organization.

33. Intranet vs. Extranet

34. Types w.r.t network Structure
CLIENT SERVER
PEER-TO-PEER

35. 1. Client Server Networks
 Server= A central dedicated powerful computer, which hosts data and other
forms of resources.
 Server based networks= one or more servers + many clients.
 Each computer that connects to the network is called a client computer.
 Users must log on to servers to gain access to resources.
 Clients such as laptops and desktop computers contact the server and request
to use data or to share other resources.

36. 1. Client Server Networks
 Server shares the storage and processing load of individual clients.
 Server can be of different types depending on their role. i.e. application
server, file server, print server.
 Example: Browsers & web servers, Banks central database

37. 2. Peer-to-Peer Networks
 P2PN / workgroup.
 No central node.
 All nodes are equal.
 Each node has access to some resources on the other nodes.
 Modern desktop operating systems such as Windows and Mac OS support
Peer-to-Peer networks.
 Example:
.
BitTorrent & Skype are based on P2PN
architecture !!

38. Types Of topology
LOGICAL LAYOUT OF CABLES AND DEVICES THAT CONNECT NETWORK
NODES.

39. Data Packets
 Data moves through network in packets.
 Packets are pieces of message broken down by the sender, for
transmission on channel, and reassembled by the receiver.
Sender / source
Receiver/ Destination
P1
P2
P3
Document
Document

40. Data Packets
 Each packet consists of
 Header part
 Source address
 Destination address
 Payload part
 Contains actual data
 Error control part
P3
Header Payload Error Control
Packet

41. Network Topologies
Topology
 Logical layout of wires and equipment
 Choice affects
 Network performance
 Network size
 Network collision detection
 Several different types

42. Common Network Topologies
 Bus topology
 Star topology
 Ring topology
 Mesh topology

43. Network Topologies
Bus topology
 Also called linear bus
 One wire connects all nodes
 Terminator ends the wires
 Advantages
 Easy to setup
 Small amount of wire
 Easy to expand
 Disadvantages
 Slow (speed depends on nodes)
 Easy to crash
 Terminators are required.

44. Network Topologies
Star topology
 All nodes connect to a single central device e.g. hub
 Packets sent to hub
 Hub sends packet to destination
 Advantages
 Easy to setup
 One faulty device cannot crash network
 Easy to detect faults and to remove parts.
 Disadvantages
 One hub can crash down entire network
 Requires more cable length
 More expensive than bus topology.
Most common topology !!

45. Network Topologies
Ring topology
All computers are connected via a cable that loops in a ring or circle.
 Packets travel in one direction
 Each computer regenerates the
data lost.
 Advantages
 Easy to install.
 No data collisions due to tokens.
 Better performance
 Disadvantages
 Slow
 Difficult to expand
 Entire network goes down.
Source
Dest.
Intermediate
Nodes

46. Ring topology - Token

47. Network Topologies
Mesh topology
 All computers connected together
 Advantage
 Reliable- Data will always be delivered.
 Disadvantages
 Lots of cable=costly
 Hard to setup and manage.

48. Network Topologies
How many cables will be required for 4 computers to ensure connectivity ?

49. Hybrid Topology
Hybrid topology is a mixture of different topologies. Example is star-bus
topology also called tree.
Easier to expand existing networks
Linear bus provides a backbone that connects multiple stars

50. Network devices

51. What is a Network Device?
 Components used to connect computers as well as other electrical
devices together in order to share resources such as printers and fax
machines.
 The different devices or components used in networking include:
 Hubs
 Switches
 Routers
 Network bridges
 Gateways
 Firewalls
 Wireless AP (Access Points)

52. What is a Hub?
 A small rectangular box that joins computers
together through ports on the back of the hub.
How does a Hub work?
 A hub receives data packets and passes on all the
Information it receives to all the other computers
connected to the hub.
 Information is also sent to the computer that sent
the information.
 Hubs can be used for a smaller network such as a
home network or a small office network.
 Hubs may not be the best option for sophisticated
or complex networks.
 Example: if computer 1 wants to communicate with computer 3, the
data will be sent to all the computers on the network since hubs do

53. Diagram of a hub network
Main PC
Hub PC 1
PC 2
Ethernet

54. What is a Switch?
 Switches look similar to hubs in that they are rectangular in
shape.
 Switches are a better option than hubs for larger networks or
home networks with 4 or more connected computers.
How does a Switch work?
• Switches work about the same way as hubs. Unlike hubs,
switches can identify the destination of a packet.
• Switches send information only to the computer that is
suppose to receive the information.
• Switches can also send and retrieve information at the same
time which makes sending information faster to retrieve
than hubs.

55. Diagram of a Switch Network

56. What is a Router?
 A specialized computer programmed to interface between different
networks.
 Routers make sure data sent over the Internet goes where it needs to
go and not where it is not needed.
 Routers are the only type of equipment that looks at every single
packet passing by on the network.
How does it works?
 A router receives data from the user.
 Looks for the remote address of the other computer making routing
decisions along the way
 Forwards the user data out to a different interface that is closer to the
remote computer

57. Diagram of a Router

58. What is a Bridge?
 A hardware device used to create a connection between two separate
computer networks or to divide one network into two.
 Filters data traffic at a network boundary and reduces the amount of
traffic on a LAN dividing it into two segments.
 How does it works?
 Each bridge consist of a MAC address and operates at layer 2 of the
OSI model
 When a packet is received on the bridge ports the forwarding table
including the MAC address is automatically updated to map the source
MAC address to the network port from which the packet originated
 The gateway then process the received packet according to the
packet’s type.

59. What is a Firewall?  Hardware or software device that protects
a computer network from unauthorized
access.
 Most home network routers have built in
firewall.
 The term “firewall” originated from
firefighting, where a firewall is a barrier
established to prevent the spread of a fire.
 A firewall works with the proxy server
making request on behalf of workstation
users.
 There are a number of features firewalls
can include from logging and reporting to
setting alarms of an attack.

60. Diagram of Firewall

61. What is a Wireless Access Point?
 A small hardware device featuring built-
in network adapter, antenna, and radio
signals.
 Configured nodes on a WLAN.
 The access point usually connects to the
router
 A hotspot is a application wireless users
can connect to the Internet.
 Aps are used throughout a home
network, usually through only one AP.

62. Diagram of Wireless Access Point
RxNT – The eprescribing System. [online image]. Available www.rxnt.com

63. Thank you!!

64. Extra Information