This document provides an overview of computer networks and wireless networks. It discusses the different types of network topologies including bus, star, ring, tree, and mesh. It also describes different network models like PAN, LAN, MAN, and WAN according to the geographical area covered. The document introduces various internetworking tools such as bridges, routers, and gateways. It provides a brief history of the OSI model and describes the seven layers of the OSI model. Finally, it discusses wireless networks and different wireless technologies including 2G, 3G, WLAN, and WiMAX.

2. Computer
Networks

3. COMPUTER NETWORK ,
NETWORK MODELS AND
TOPOLOGIES

4. COMPUTER NETWORK
 Computer network connects
computers in a manner to
enable meaningful transmission
and exchange of data between
them.
 In computer network we can
share information, share
resources (hardware, software).
 Computer network is also called
Information network.
For Example: Internet

5. HISTORY OF COMPUTER NETWORK
 The first-ever Computer-to-Computer link was
established on ARPANET (Advance Research
Project Agency Network) , the precursor to
the Internet, on October 29, 1969.
 The message on the ARPANET was sent by
UCLA student programmer Charles S Kline.

6. NETWORK TOPOLOGIES
 A Network
Topology refers
to the way in
which nodes
are connected
in network.

7. BUS TOPOLOGY
 In Bus Topology, all
nodes are connected to
a single communication
line.

Advantages
 Reduce number of
physical line.
 Failure of node does
not effect the network
 .
Disadvantages
 Communication line
fails, the whole network
fails.

8. STAR TOPOLOGY
 In a star topology all computers
or nodes are directly connected
to a central device called hub
or switch.
Advantages
 New nodes can easily added
and removed to and from the
central device.
 If any node fails, other nodes
are not affected
 .
Disadvantages
 If the central device fails the
whole network fails.

9. RING TOPOLOGY
 In a ring topology, each
computer is connected to
the next computer and the
last computer is connected
to the first.

Advantages
 It is less expensive than star
topology.
 All computers has equal
access to network.
Disadvantages
 If one node fails, the entire
network stops functioning.
 Adding and removing nodes
affects the network

10. TREE TOPOLOGY
 Tree topology has
combined features of
bus and star topologies.
Typically to form a tree
network, multiple star
topologies are
combined together
through Central cable
or bus.

11. MESH TOPOLOGY OR COMPLETELY
CONNECTED NETWORK
 In mesh topology, each
node has directly link, with
all other nodes.
Advantages
 It provides multiple routes
for date communication.
 It ensures data privacy.
 Communication is very fast.
Disadvantages
 It is very expensive.

12. HYBRID NETWORK
 Hybrid network
combines two or more
networks. A hybrid
topology is a type of
network topology that
uses two or more other
network topologies
including bus
topology, mesh
topology, ring
topology, star topology,
and tree topology.

13. METHODSTYPES

14. Types of Network
 Depending upon the geo graphical area covered by a
network, it is classified as:
 Personal Area Network (PAN)
 Metropolitan Area Network (MAN)
 Local Area Network (LAN)
 Wide Area Network (WAN)

15. Personal Area Network (PAN)
 A Personal Area Network is a computer network used for communication among
computer devices, including telephones, tablets, and personal digital assistants.
 The reach of a PAN is typically a few meters.
 Personal area network may be wired with computer buses such as USB and
FireWire.
 A Wireless Personal Area Network can also be made possible with wireless network
technologies such as, Bluetooth, Wireless USB.

16. Advantages & Disadvantages of PAN
Advantages:
 The PAN is a personal network of one or two person so there is no risk of
any leak of data.
 They are quick and easy.
 PAN usually need less technical skill.
 WPAN devices are easy portable.
Disadvantages:
 PAN have limited range.
 Devices are not compatible with each other.
 Devices with inbuilt WPANs are more expensive.

17. Metropolitan Area Network (MAN)
 MAN is a network system that covers area of a single city.
 It covers a smaller geographical area than a WAN.
 Mobile phones systems often use MAN.
 In this type of network, fiber optics cables are used as communication
media.
 It is very high speed network.

18. Advantages & Disadvantages of
MAN
Advantages:
 It provides a good back bone for a large network and provides greater
access to WANs
 The dual bus used in MAN helps the transmission of data in both direction.
 A MAN usually encompasses several blocks of a city or an entire city.
Disadvantages:
 More cables required for a MAN connection from one place to another.
 It is difficult to make the system secure from hackers and industrial spying.

19.  A Local Area Network is a group of computers and associated devices that
share a common communications line or wireless link.
 The computers used in LAN also require network interface card.
 They are connected to each other in a limited area. Typically, this area is
up to ONE KM.
 LAN is also known as Local Net.
Local Area Network (LAN)

20. Advantages & Disadvantages of LAN
ADVANTAGES:
 The resources can be shared among different users.
 All data is stored on the central server. So it becomes very easy to manage
the data.
 LAN is not very expensive.
 Data transmission in a LAN is very high.
DISADVANTAGES:
 If central server is infected by virus, then the important data stored on
server may be corrupted and the entire network may also be effected.
 All nodes depends on the central computer ( or Hub ), if any component of
server fails, then entire network will stop working.

21. Wide Area Network (WAN)
 A Wide Area Network is a type of computer network
that covers a large area such as different cities of
country or different countries of the world.
 Computers and other devices in a WAN are often
connected through telephone lines.
 The internet is the world’s largest WAN.
 Many large organizations make use of WAN as
enterprise network.

22. Advantages & Disadvantages
of WAN
Advantages:
 WAN covers a large geographical area.
 Message may be shared and communicated all over the world.
 The software can be shared between different users all over the
world.
 The data of an organization is stored in a single location. Everyone
on the network can use the same data.
Disadvantages:
 WAN becomes expensive to install. WANs are very costly.
 It is very expensive to run the WAN.
 WAN is very slow for data transmission.
 If the server fails, the entire network is effected.

23. INTERNETWORKING
TOOLS

24. Internetworking tools

25. Internetworking tools
 Interconnecting two or
more networks to form
a single network is
called Internetworking
and the resulting
network is called
internetwork.
 Internetworking may
or may not be differ in
protocol and topology.
 The goal of
Internetworking is to
Interconnect different
physical networks and
to hide their details,
enabling the
internetwork to function
as a single coordinated
unit.

26. Bridge
Bridge is used to connect
similar networks
segments. It may or
may not use the same
protocols at physical
and data link layers.
 For Example, a bridge
can connect two
networks, one of which
uses fiber-optic
communication
medium and the other
uses coaxial cable.
 However, networks
must use the same
high level protocols (e.
g, TCP/IP) to
communicate.

27. Router
 Router is used to connect two
or more different or similar
networks.
 Router is smarter than bridge
because they not only copy a
data from one network
segment to another but also
choose the best route for the
data by using information in a
routing table.

28. Gateway
 Gateway is used to
connect two or more
different types of
networks.
 It is the most
sophisticated(great)
Internetworking tool.
Sometimes gateway
perform the routing
information
 Gateway convert data
packet from one format
to another format.

29. Difference between Router and
Gateway
 Route traffic from one network to
another
 Supports dynamic routing.
 Work on layer 3 &layer 4 of OSI
Model.
 Router forwards packet of data
from one network to another.
Router Gateway
 Translate data from one
format to another format.
 Doesn't support dynamic
routing.
 Work up to layer 3 to 5 of OSI
Model.
 Gateway is a device that
convert one protocol format
to another.

30. OSI Model

31. History of OSI model
 In 1979 ISO & CCITT (two international standards
organization) developed a document that defined
similar networking models.
 In 1983, these two documents were merged to form a
standard called “The Basic Reference Model for Open
System Interconnection". It is simply called OSI Model.
 OSI Model had two major components, an abstract
model, called seven layer model & a set of specific
protocols.
 It was published in 1984 by ISO as standard ISO7498 &
CCITT as standard X200.

32. Charles bachman
The concept of seven layer model was provided by
the work of Charles Bachman at Honeywell
Information Services.

33. OSI MODEL
 OSI stands for Open System Interconnection.
 OSI is the most widely accepted model for
network communication.
 OSI model provides a useful structure for
defining and describing various process of
networking.
 It organizes the communication into seven
layers.

34. OSI MODEL

35. WIRELESS
NETWORKS

36. WIRELESS NETWORKS
 Wireless network is any type
of computer network that
uses wireless transmission
media to communicate
between nodes.
 Wireless networks are
computer networks that are
not connected by cables of
any kind.
For Example: Cellular Phones

37. Types of Wireless Computing Systems
Wireless computing systems are
of two types:
1. Fixed wireless systems
2. mobile wireless systems

38. 1: Fixed Wireless Systems
 These wireless computing systems support little or
no mobility of their computing equipment.
2: Mobile Wireless Systems
 These wireless computing systems support
mobility of users and allow mobile users to access
at any time or place. Resulting computing is called
mobile computing or nomadic computing.

39. Issues in Wireless Computing Systems
Computing systems faces many challenges. The important
ones among them are:
1. Lower bandwidth
2. Variable bandwidth
3. Higher error rate
4. Increased security concern
5. Dynamically changing network
6. Lost or degraded connection
7. Support for routing and location management function
8. Limited power

40. Wireless Technologies
 Some wireless technologies are:
 2G and 3G Technologies
 Wireless LAN (WLAN)
 WiMAX
 Wireless Local Loop(WLLs)

41. 2G and 3G Technologies
 2G was digital, circuit based and narrowband but
suitable for voice and limited data communication.
 3G is suitable for online multimedia, data applications
and voice.
Wireless LAN(WLAN)
 A Wireless Local Area Network (WLAN) is a LAN that
enables wireless communication among equipment
which are the part of LAN.

42. WiMAX
 WiMAX is a technology based on IEEE 802.16 for
providing wireless communication in WMANs
Wireless Local Loops(WLLs)
 Wireless Local Loop technology supports fixed
wireless systems and provides several MHz of
bandwidth which offer high-speed internet.

43. COMMUNICATION
PROTOCOL

44. COMMUNICATION PROTOCOL
 A set of rules for exchanging
data between computers
connected to a network is called
NETWORK PROTOCOL. It
provide a method for efficient
exchange of data between
senderreceiver , and for proper
interpretation of controls and
data transmitted as raw bits and
bytes.

45. RUles of COMMUNICATION PROTOCOL
1. Data sequencing
2. Data routing
3. Data formatting
4. Flow control
5. Error control
6. Procedure & order of transmission
7. Connection establishment
8. Data security
9. Log information

46. Concept of Layered PROTOCOL in
Network Design
• Modern computer networks have modular
design for easy and efficient handling of system.
They consist of several modules, which are
grouped into layers logically. Each layer has its
own set of protocols. A particular layer of one
machine communicates only with corresponding
layer of another machine by using protocols of
this layer.

47. Reason for Using Layered Protocol
1. Protocol of network are complex
2. Layered Protocol provides well-defined interface
between layers
3. Layering of protocols also allows interaction
between functionally paired layers

48. Network Interface Card (NIC)
 NIC is a hardware device that connects a computer
to a network, both functionally and physically. It is
Printed Circuit Board(PCB), which connects to one of
the expansion slot of computer, and provides a port
for attaching a network cable.NIC connects directly
to a computer’s IO bus. NIC ‘s ROM has the
network’s physical-layer communication protocol.
There are different NICs for different netwrks. NIC is
also called Network Card.