What is the computer network? Bunch of computers connected to each other Now computers do not mean just pc’s. Now a bunch of computers include printers, cell phones, laptops, etc Now next question is what do you mean by share data or share information?TYPES OF NETWORKS.Parts of Networks.

1. LOGO
Computer Networks
Jigar Jobanputra

2. LOGO
What is the computer network?
 Bunch of computers connected to each other
 Now computers do not mean just pc’s.
 A bunch of computers include printers, cell phones, laptops, etc
 The computers are connected to each other using some cable. In
below diagram I have used a cable to connect the bunch of
computer system.

3. LOGO
Cont…
 But network can also be established using WI-FI or Satellite etc.
 The main purpose of computer network is to share data, information
and Resources.
 You can share data using microwave, radio wave, infrared, fiber
optics cable, etc.

4. LOGOwhat do you mean by share data or share
information?
 E.G. If I am in a school and I want to send some files to the subject
teacher of a computer. Data does not means only boring text data it
also includes pictures, videos, etc.
 So by using computer networks we can transfer the data from one
computer to another computer.
 Biggest computer network example is “INTERNET”.

5. LOGO
Now next point is TYPES OF NETWORKS.
 We can classify our network by many types for example if you are
using the computer network in your home between the two systems
it is your personal Network.
 If one business firm is connected with the some network it becomes
Professional Network.
 But the easiest way/ standard to classify the network is according to
its Reach/size.
 LAN- LOCAL AREA NETWORK
 MAN- METROPOLITON AREA NETWORK
 WAN – WIDE AREA NETWORK

6. LOGO
what is LAN?
 LAN means the interconnected computers in the same house or
building.
 It is the smallest network of the computer networking system.
 e.g. computer lab in school or colleges, Cybercafé, small business
offices.
 Now the question is why we want to connect the systems in colleges
or in a school or in a cybercafé??

7. LOGO
Cont…
 To share resources
 If you are working in a computer laboratory with 60 systems,
definitely you are not going to purchase 60 printers. You will connect
all the systems such that all the systems can use the same printer.
 Next networking classification is MAN
 It is basically bigger than LAN
 The computers that connected in one colony (Geographical Area) or
city are called METROPOLITON AREA NETWORK.

8. LOGO
why we want MAN?
 For e.g., we have a city hospital in a middle of the city. And a
medical college at the distance of the 20 km from the city now
college wants some information about the patients admitted in the
hospital for research.
 Now both the systems are connected at the long distance of 20 km
using MAN.
 They use copper cable or fiber optics for the connection.
 Next Classification is WAN (Wide Area Network)
 WAN is made up of multiple MANS.
 Computer connected in less than 30 miles of area is called WAN.
 For e.g, Telephone Company connections connected in all over the
country is called WAN.
 INTERNET is the best example of WAN.

9. LOGO
Cont…
 All the computers that are connected with the WAN are either using
fiber optics (High speed cable) or using satellite.
 Next point is Parts of Networks.

10. LOGO
Cont…
 Any computer network made up of two parts NODES(pc’s, laptops,
cell phone, routers, printers, modems) & Communication
Media(copper wire, fiber optics, radio waves, WI-FI).
 The node (any device in the computer network) is connected using
(copper wire, fiber optics, radio waves, WI-FI) Communications
Media.
 To understand the working of the network we have to understand
first the working of the internet.

11. LOGO
How internet works?
 Now suppose you have made one wonderful website using some
core language like PHP, or ASP.NET. And now you want your
friends, family and others to visit the website.
 Now even the computers that are connected with your pc are not
able to visit the website, because your operating system will not
allow them to access the website.

12. LOGO
How the people will see your website??
 To store that website we need a special type of system that is called
web server.
 The web servers generally have lots of memory and power.
 The web server is special computer that is accessible to many
users, for example Google server that is accessible to worldwide.

13. LOGO
what is host and what is client?
 For suppose I am using my laptop to visit some websites for the
research. So, whenever I typed any URL in my web browser that
request will be passed to some web server where all the web pages
are stored.
 In this case my laptop will become client and the web server where
all the files are stored of particular website will become host.
 In below showing figure the client and host are shown.

14. LOGO
Cont…
 The client will always get the data/files/pages from the host.
 And host will always respond (gives) the requested data/files/pages
to the client.
 This is the relationship between the client and the host.

15. LOGO
NIC (Network Interface Card).
 To connect with any network the computer must have the NIC. That
is network interface card.
 The Network Interface Card is made up of two parts one is to
connect to the motherboard of the computer and other is to connect
to a network.
 The yellow part shown in the picture is used to connect the NIC to
the motherboard of computer.

16. LOGO
cont…
The yellow part of the picture is used to connect the communication
media to connect to a network.

17. LOGO
Network Interface Card.

18. LOGO
Ethernet cable

19. LOGO
You can also insert WIFI card to your system. That is useful to connect your system to the
WIFI Network.

20. LOGO
what do you mean by Network protocol??
 The network protocol we can define like that it is the basic rules for
the successful communication between the computers or systems.
 For suppose now we have one nice laptop and internet connection
now first of our system will ask the web server that, “CAN I
CONNECT TO YOU”?
Than the server will reply “Yes, you can connect you have my
permission”.
 Than next request will be from client side for some page for e.g.
www.abc.com/index
 In reply to the request the server will give the particular page to the
client.
 This communication between the client and the host is possible
because they are following the same protocol (rule).
 In computer network if any computer wants to communicate with
any other computer than both the computer should follow the same
protocol for a successful communication.

21. LOGO
what do you mean by Topology/Layout??
 Computer topology means how you are going to connect your
computers in a network. How you are going to set up the wires or
connect the computers.
 There are many ways available to connect your computer with the
wires. Some common points that must be taken care while selecting
the topology are COST, EASE OF MAINTAINANCE.
 There are many different topologies available some common
topologies are
 Bus
 Star
 Ring
 Mesh

22. LOGO
Cont…
 Bus: - in bus topology single main network (Ethernet) cable is
passed through all the nodes in the network.
 In bus topology we need a special thing that is called terminators.
Terminators are the special devices that is installed at the end of
network cable and the work of the terminators is when signals goes
to the end of the network cable the terminators will not bounced the
signals back and it will absorbed it.
 Advantages
 It is very easy to setup.
 It is not so much expensive.
 It is appropriate for small office and small houses.
 Disadvantages
 This is very old topology.
 It is hard to detect an error.

23. LOGO
Cont…
 Star: - Many nodes in a network are connected to the one central
device is called star topology. The central node can be a switch or a
router. The devices can be connected using the Ethernet cable, or
WIFI etc.
 But basically all the nodes in the network are connected to the
central device of a network.

24. LOGO
Cont…
 Advantages
 It is very easy to manage.
 It is very simple to setup & expand.
 If one node goes down or crash it does not affect the other nodes in
the system.
 Error detection is easy in the network.
 Disadvantages
 Entire network is dependent on the central device, because all the
nodes are connected to the central device.
 Star topology needs more cable than other topologies.

25. LOGO
Cont…
 Mesh: - when more than one topology is used to connect to the
network, is called mesh or hybrid topology.
 In above figure each and every node is connected to the every node
of the network.
 So this layout or pattern is call mesh topology.

26. LOGO
Cont…
 Advantages
 If one communication channel goes down than from another
channel we can access the data as each node have more than one
communication channel.
 If we connect more nodes to the topology actually it is good for the
network as it provides more communication channel in a network.
 Disadvantages
 It is very expensive.
 We need more ports (NIC) in our system and more cables to setup
this topology.