The document discusses various topics related to computer networks including the need for networks, importance of networks, solutions for sharing resources over a network like site licenses and network versions of software. It also covers different types of network topologies - star, bus, ring and mesh. The star topology allows devices to connect to a central hub, making it easy to install but failure of the hub disables all devices. The ring topology arranges devices in a closed loop but failure of a single node breaks the entire network. The mesh topology connects all devices directly but requires extensive cabling. Finally, it notes considerations for choosing a suitable topology include cost, cable requirements and ability to support future growth.

1. Networking Basics

2. Need of Computer Network
 Simultaneous Access of Peripheral Devices
 Remote File sharing
 Resource and Data sharing
 Communication and collaboration
 Remote access
 Data protection
 Personal Communication

3. Importance of Networks
 Without networking complete setup can be
costly:
 Purchasing dozen and hundreds copies of
software can be expensive
 Multiple Peripherals can be vey expensive.
 Installation and Configuration a program multiple
times
 Computer can take a lot of time and labor ,
maintaining many separate installation of a
program is an expense.

4. Solution
 Site licenses
 Purchase a site licenses for an application
 Buy single copy of an application
 Pays the developer for a license to copy
the application onto a specific number of
computers
 Each user has complete , individual copy
on her/his computer
 But pay less money than purchasing a
complete copy of the software for each
user

5. Solution
 Network Version
 Connect user’s computer to a central
network server
 Only one copy is installed on server
 Client can access it
 Simply load it from server into RAM of
their own desktop computers.

6. Solution
 Network Version

7. Shared Peripheral Devices
 peripheral devices, which can cost
thousand of dollars
 High laser printer
 Expensive to provide every worker with a
personal printer.
 Shared printer would cost effective
 Multiple users can use single printer
 Easy to manage

8. Shared Peripheral Devices
• Devices can be
connected directly to
a network
• It may connected to a
printer server. Which is
a computer that
manages one and
more printers

9. Personal Communication
 E-Mail

10. Personal Communication
 Companies connect their private networks to the
internet.
 so worker can send/receive messages across
internet from people outside the company’s
network.
 For Example:
 UOG Email Sever
 Every Faculty member is given an email ID:
 For example: Waqar.azeem@uoglahore.edu.pk
(Send your Assignments on this ID for plagiarism
check!!!)

11. Personal Communication
 Video-conferencing
 Is a multi-way communication in real
time through network
 CODEC(compressor/de compressor)
 Which processes the audio and video
 A codec is a device or computer program
capable of encoding or decoding a digital
data stream or signal.
 Virtual Presence

12. Personal Communication
 Video-conferencing

13. Personal Communication
 Audio-Conferencing
 Provides audio link similar to conventional telephones
 But offers high quality audio
 Communication between group of participants can also be
enable.
 Data-Conferencing
 Refers to a communication session among two or more
participants sharing computer data/ application in real time.
 Software can be run/ controlled by both users.
 Remote Desktop Sharing
 Conjunction of audio and video

14. Data Conferencing Tools

15. VOIP
 Voice over internet protocols
 Technology that enables network managers to
route phone calls and fax transmissions over
the same network they use for data.
 Transmit s the sound of your voice over
computer network to using internet
protocol(IP).
 How VoIP Works: With VoIP, analog voice calls
are converted into packets of data. The
packets travel like any other type of data,
such as e-mail, over the public Internet and/or
any private Internet Protocol (IP) network.
Using a VoIP service, you can call landline or
cell phones.

16. VOIP

17. The Other Uses of a
Network
 Easier data backup
 Backup copies data
 Server data backed up in one step

18. Types of Network

CATEGORIES
OF
NETWORKS

19. Types of Networks
 Local Area Network(LAN)
 Wide Area Network(WAN)
 Hybrid Networks
 Campus Area Networks(CANs)
 Metropolitan Area Network(MANs)
 Home Area Networks(HANs)

20. LAN
 Connect using cable
 Hundreds computers
• Systems are close to each other
• Contained in one office or building
 Twisted pair cable or Co-axial cable
connects the plug in cards to form a
network.
 Example
 In large company two departments located on same floor of
a building may have their own LAN network.
 But communicate between two LANs to share the data.

21. Local Area Network

22. WAN
 Wide Area network
 Connect systems across wide
geographical area
 Connect through internet or
telecommunication
network(company phone)
• Links computer systems a few
miles or thousands of miles
 Example:
 Company headquarters in one
country and marketing office is in
another country.

23. CAN
 Several LANs located in
various locations on a
college or business
campus
 Smaller than a WAN
 Use devices such as
switches, hubs, and
routers
 1 – 5 km range.
 Within the city
Campus Area Network

24. MAN
 Metropolitan Area Network
 Large network that connects different
organizations
 Not owned by single organization
 Maintain by group or single network
provider that’s sells its networking service
to corporate customers
 Provide shared connection to other
networks.
 Large range

25. MAN
 If the campuses of an organization are in different
cities:

26. HAN
 Home Area Network
 Small scale network
 Connects computers and entertainment appliances
 Found mainly in the home
 Usually within a range of 32 feet
 Usually use wireless technology

27. BASIS LAN MAN WAN
Full Form Local Area Network Metropolitan Area
Network
Wide Area Network
Range A communication
network linking a number
of stations in same local
area. Range is 1 to 10 km
This network shares the
characteristics of
packet broadcasting
networks. Range is100
km
A communication
network distinguished
from a Local Area
Network. Range is Beyond
100 km
Media Used Uses guided
media(copper twisted
pair, copper coaxial
cable, optical fiber)
Uses guided as well as
unguided media
Uses unguided
media(wireless)
Speed A high speed i.e. 100kbps
to 100mbps
Optimized for a large
geographical area than
LAN.
Long distance
communications, which
may or may not be
provided by public
packet network.
Cost cheaper costly expensive
Equipment
needed
NIC, switch and hub Modem and router Microwave, radio,
transmitters and receivers
protocols Attached Resource Frame relay and ATM, FDDI, SMDS

28. Internet
 A worldwide interconnection of computers and
networks that use the Internet Protocol IP.
 It allows for WWW, FTP, VoIP, Gaming, File sharing,
video, email.
 There are millions of networks all over the world
and combination/network of these millions of
networks is called internet.

29. Q: What is IP?????????
The Internet Protocol (IP) is the method or
protocol by which data is sent from one
computer to another on the Internet. Each
computer (known as a host) on the Internet
has at least one IP address that uniquely
identifies it from all other computers on the
Internet.

30. Intranet & Extranet
 An intranet is a private network, operated
by a large company or any other
organization, which uses internet
technologies, but is insulated from the
global internet.
 An extranet is an intranet that is
accessible to some people from outside
the company, or possibly shared by more
than one organization.

31. Intranet & Extranet

32. How Networks Are
Structured
 Client/Server network
 Nodes and servers share data
 Nodes are called clients
 Servers are used to control access
 It may be LAN and WAN
 Database software
 Access to data controlled by server
 Send query to the server ,which searches
the database and return information to the
user’s PC

33. How Networks Are
Structured
 Peer to peer networks (P2PN)
 All nodes are equal
 Similar type of software that supports the sharing of
resources.
 Each node controls its own resources
 Windows 2000, Me, XP, Macintosh, windows 9x and
modern OS provides P2PN.
 No other software required
 User setting password on shared folder

34. How Networks Are
Structured
 Client-Sever & Peer to Peer Network

35. Q: What’s the difference between Client Sever
and Peer 2 Peer Networks?
There’s a huge difference between client/server and
peer-to-peer networks. For instance, a peer-to-peer
network has no central server. Each workstation on the
network shares its files equally with the others. There’s no
central storage or authentication of users. Conversely,
there are separate dedicated servers and clients in a
client/server network. Through client workstations, users
can access most files, which are generally stored on the
server. The server will determine which users can access
the files on the network.

36. Network
topologies

37. Topology
 Topology refers to the layout of connected
devices on a network.
 Or How the network devices can be arranged in a
network.
 Factors need to be considered to select topology
 Distance between network devices
 The speed at which data travels around the network
 Cost of setting up the network
 And User’ s Requirements

38. Topology
 Packets/datagram
 Pieces of data transmitted over a
network
 Packets are created by sending node
 Data is reassembled by receiving node
 Packet header
 Sending and receiving address
 Control data that helps the receiving node
reassemble in right order

39. Importance of topology
 Appropriate topology for organization’s need will
move data packets as efficiently as possible
 Preventing collision
 Multiple nodes try to transmit data at same time

40. Topology
 Some logical topologies of networking
 Star
 Bus
 Ring
 Mesh

41. Bus Topology

42. Bus Topology
 Here one long cable act as a backbone to link
all the devices are connected.
 This allows only one device to transmit at a
time.
 A device want to communicate with other
device on the n/ws sends a broadcast message
onto the wire all other devices see.
 But only the intended devices accepts and
process the message.

43. Bus Topology
 Advantages:
1. Ease of installation
2. Less cabling
Disadvantages:
1. Difficult reconfiguration and fault isolation.
2. Difficult to add new devices.
3. If any fault in backbone can stops all
transmission.

44. Star Topology
 Here each device has a dedicated point-to-
point link to the central controller called
“Hub”(Act as a Exchange).
 There is no direct traffic between devices.
 The transmission are occurred only through
the central “hub”.
 When device 1 wants to send data to device 2;
First sends the data to hub. Which then relays
the data to the other connected device.

45. Star Topology

46. Star Topology
 Advantages:
1. Less expensive then mesh since each device
is connected only to the hub.
2. Installation and configuration are easy.
3. Less cabling is need then mesh.
4. Robustness.(if one link fails, only that links
is affected. All other links remain active)
5. Easy to fault identification & to remove
parts.

47. Star Topology
 Disadvantages:
1. Even it requires less cabling then mesh
when compared with other topologies it
still large.(Ring or bus).
2. Dependency(whole n/w dependent on one
single point(hub). When it goes down.
The whole system is dead.
3. Hub device can be expensive

48. Applications
 Star topology used in Local Area
Networks(LANs).
 High speed LAN often used star

49. Ring Topology

50. Ring Topology
 Here each device has a dedicated connection
with two devices on either side.
 The signal is passed in one direction from device
to device until it reaches the destination and each
device have repeater.
 When one device received signals instead of
intended another device, its repeater then
regenerates the data and passes them along.
 To add or delete a device requires changing only
two connections.

51. Ring Topology

52. Ring Topology
 Advantages:
1. Easy to install.
2. Easy to reconfigure.
3. Fault identification is easy.
4. No danger of collisions because only one packets
travels at a time
Disadvantages:
1. Unidirectional traffic.
2. Break in a single ring can break entire network.

53. Ring Topology
 Applications:
 Ring topologies are found in some office buildings or
school campuses.
 Today high speed LANs made this topology less popular.

54. Mesh Topology

55. Mesh Topology
 Here every device has a point to point
link to every other device.
 1 node must be connected with n-1
nodes.
 A fully connected mesh can have n(n-
1)/2 physical channels to link n
devices.

56. Mesh Topology
Advantages:
1. They use dedicated links so each link can
only carry its own data load. So traffic
problem can be avoided.
2. It is robust. If any one link get damaged it
cannot affect others.
3. It gives privacy and security.(Message
travels along a dedicated link)
4. Fault identification and fault isolation are
easy.

57. Mesh Topology
 Disadvantages:
1. The amount of cabling and the number of
I/O ports required are very large. Since
every device is connected to each devices
through dedicated links.
2. The sheer bulk of wiring is larger then the
available space.
3. Hardware required to connected each
device is highly expensive.

58. Mesh Topology
 Applications:
1. Telephone Regional office.
2. WAN.(Wide Area Network).
3. P2P Networks

59. Considerations for
choosing topology
 Money-Bus n/w may be the least expensive way to
install a n/w.
 Length-of cable needed- the linear bus n/w uses
shorter lengths of cable.
 Future growth-with star topology, expending a n/w is
easily done by adding another devices.
 Cable type-most common used cable in commercial
organization is twisted pair. Which often
used with star topologies.

61. SUMMARY
RING TOPOLOGY
DEFINITION
•Cable forms
closed ring or
loop, with all
computers and
devices
arranged along
ring.
ADVANTAGE
•Data is quickly
transferred without a
‘bottle neck’.
•The transmission of
data is relatively
simple as packets
travel in one direction
only.
DISADVANTAGE
•Data packets must pass
through every computer
between the sender and
recipient therefore, this
makes it slower.
•If any of the nodes fail
then the ring is broken
and data cannot be
transmitted successfully.
•It is difficult to
troubleshoot
the ring.

62. SUMMARY
DEFINITION
•All devices
connect to a
central device,
called hub.
ADVANTAGE
•Easy to install and
wire.
•Security can be
implemented
in the hub/switch.
DISADVANTAGE
•Requires more cable
length
than a linear
topology.If the hub or
concentrator fails,
nodes attached are
disabled.
More expensive than
linear bus topologies
because of the cost of
the concentrators.
STAR TOPOLOGY
•Easy to detect faults
and to
remove parts

63. 1.Provide redundant
SUMMARY
DEFINITION
•In the mesh
topology each
computer are
connected with
each other by
separate
cable..
ADVANTAGE
•1.Provide redundant
path between
device..
The network can be
expanded without
disruption to current
user..
DISADVANTAGE
Require more cable
then other topology .
Complicated
implementations.
MESH TOPOLOGY

64. Network Protocols
 Language of the network
 Rules of communication
 Error resolution
 Defines collision and collision recovery
 Size of packet
 Packet Transmission

65. Transmission modes
 Q Explain the two types of data transmission
modes?

66. Network Protocols
 TCP/IP
 Transmission Control Protocol/Internet Protocol
 Most popular protocol
 Machines assigned a name of 4 numbers
 IP address
 209.8.166.179 is the White House’s web site
 DHCP (Dynamic Host Configuration Protocol)
 Simplifies assignment of IP addresses
 Required for Internet access
 Unix

67. TCP/IP


68. Network Protocols
 IPX/SPX
 Internet Packet Exchange/Sequenced Packet
Exchange
 Older protocol
 Associated with Novell Netware
 Replaced by TCP/IP

69. Network Protocols
 NetBEUI
 Network BIOS Extended User Interface
 Used by Windows to name computers
 For small offices or home
 Doesn't expand well into larger environment
 This protocol provides the user interface. And
Manages LAN.
 It also allow the computers to communicate
within a local area network.

70. Data
Communication
with standard
Telephone Lines
and Modem

71. introduction
 Telephone
 Two way transmission of electronic information
 Carry voice message in the form of analogue signal
 But difficult for a typical computer
 Computer and telephone lines use to connect with
internet.
 Need hardware for this purpose

72. MODEM
 Modulator-demodulator
 Computer communicates in
digital/binary
 Consists of on/off pulse representing 1s
and 0s
 As on our ptcl phone line data
communication is analog
 So Modem convert digital signals to
analogue signal that can travel over
standard telephone lines.

73. MODEM
 Modulator
 The modem turn the computer ‘s digital signals into
analog signal. Then transmit across phone lines.
 Digital to analogue
 Demodulator
 Receives analogue signals form the phone lines and
convert it into digital signals for the computer.
 Analogue to Digital

74. Modulator-demodulator

75. Modem
 Modem’s transmission speed:
 The rate at which it can send data is measured in
bits per seconds(bps)
 Maximum transmission speed is 56000 bits per
seconds or 56 kilobits per seconds, is called 56 K
modem

76. MODEM
External Internal
• Is a circuit board that
plugs into one of the
computer’s
expansion slot
• Also available in the
form of PC card in
laptop

77. Uses for a Modem
 Uploading
 Downloading
 Transfer protocols for modems:
 Xmodem
 Ymodem
 Zmodem
 MNP(Microcom Networking Protocol)

78. Using Digital connection
 Different phone will be needed.
 A digital phone that translates voice into bits rather
than an analog signal is needed.
 No need of modem. An adapter that reformats the
data so that it can travel through the telephone
lines is needed.
 Data can be sent very quickly

79. Using Digital connection
 Local telephone companies are upgrading
 Service will faster and more reliable
 New phones will be needed
 Modems will need to be upgraded
 Data are transmitted in encrypted form

80. Broadband connection
 Broadband:
 Term is used to describe any data connection that
can transmit data faster than is possible through dial
up connection using modem.
 Broadband connections called integrated
services digital network(ISDN).

81. Broadband connection
 ISDN lines
 Integrated Services Digital Network
 Basic rate interface(BRI) uses three channels
 Two data channels each support 64 Kbps
 Error correction channel
 Primary rate ISDN (PRI)uses 24 data channels
 T1 uses 24 data channels
 T3 offers 672 digitized voice channels of 64 Kbps
each

82. Broadband connection

83. DSL technologies
 Digital Subscriber Line
 Popular with home users
 Speeds range from 100 Kbps to 30 Mbps

84. DSL technologies
 Asymmetrical DSL (ADSL)
 Upload speed slower than download speed
 Symmetrical DSL (SDSL)
 Rate adaptive DSL(RADSL)
 High bit rate DSL(HDSL)
 ISDN DSL (IDSL)
 Very High bit rate DSL(VDSL)

85. Cable modem connections
 Popular with home and office users
 Speeds between 1 and 3 Mbps
 Requires a cable modem

86. Cable modem connections
 Download speed 27Mbps is same as T1
 but limitation on speed are the number of user
in the local neighborhood sharing the same
connections
 Amplifier are used to keep the signal strong

87. ATM
 Asynchronous Transfer Mode
 Efficient transfer of video and sound
 Communication companies
 Requires a special NIC and hardware

88. Wireless Networks
 No cable to pull
 Mobile devices access network resources
 Mobility and flexibility for office workers
 Wireless 802.11
 Also called Wi-Fi
 Speeds upto 11 Mbps
 IEEE standard
 Institute of Electronic and Electrical Engineers
 Several versions
 802.11b connects up to 11Mbps
 802.11g connects up to 56Mbpsame type of devices

89. Wireless Access Point
 Center of a wireless network
 WAPS combined cover a larger area
 Distance to WAP(Wireless Application Protocol )
determines bandwidth
 Range is 50 to 150 meters
 Extension points can extend range

90. Wireless Networks
• Wireless Adapters
– Used by devices to connect
– Includes signal strength software