Course: Computer Network
(CNE)
Ms. Minal T.

Teaching scheme

Course Outcomes
SR.NO. Course Outcomes
CO1 Use basic concept of networking for setting up computer networks
CO2 Setup a computer network for specific requirement
CO3 Configure basic network services
CO4 Configure the different TCP/IP services
CO5 Implement subnetting for improved network address management

Chapter No. 1
Fundamentals of Computer Networks

Computer Network
• Networks: - A network is a set of devices (often referred to as nodes) connected by communication links. A
node can be a computer, printer, or any other device capable of sending and/or receiving data generated
by other nodes on the network
• Computer Network: A set of devices interconnected to each other for sharing information/data, resources
within a particular time limit.

Need of Computer Network
Computer networks help users on the network to share the resources.
• Hardware sharing
• File sharing
• Application sharing
• User communication
• Network gaming
• Voice over IP (VoIP)

Application of Computer Network
• Sharing the resources such as printers among all the users.
• Sharing of expensive software & hardware.
• Communication from one computer to other.
• Exchange of data & information amongst the users, via the network.
• Sharing of information over the geographically wide areas.
• For connecting the computers between various buildings of an organization.
• For educational purposes.

Advantages of Computer Network
• Access to remote information
• Resource Sharing
• Saving Money
• High Reliability
• Providing powerful communication Medium
• Person-to-person communication

Classification of Computer Network based on Geographical Area

Local Area Network
• A Local Area Network (LAN) is a private network that
connects computers and devices within a limited area like a
residence, an office, a building or a campus.
• On a small scale, LANs are used to connect personal
computers to printers.
• However, LANs can also extend to a few kilometers when
used by companies, where a large number of computers
share a variety of resources like hardware (e.g. printers,
scanners, audiovisual devices etc), software (e.g. application
programs) and data.

Metropolitan Area Network
• A metropolitan area network (MAN) is a network with a
size greater than LAN but smaller than a WAN. It
normally comprises networked interconnections within a
city that also offers a connection to the Internet.

Wide Area Network
• A wide area network (WAN) is a telecommunications
network that extends over a large geographic area for
the primary purpose of computer networking.
• In its simplest form, a wide-area network (WAN) is a
collection of local-area network (LANs) or other
networks that communicate with one another.

Difference between LAN MAN & WAN

Classification of Computer Network based on Transmission Technology
The transmission means, is that sending a signal from one location to another.
The transmission technology can be categorized broadly into two types:
1. Broadcast network
2. Point to point network

Broadcast Network
• Broadcast networks have a single communication channel that is shared or used by all
the machines on the network. Short messages called packets sent by any machine are
received by all the others.
• Broadcast systems generally use a special code in the address field for addressing a
packet to all the concerned computers. This mode of operation is called broadcasting.
• Upon receiving a packet, a machine checks the address field. If the packet is
addressed to it then the packet is processed, otherwise the packet is ignored.

Point-to-point Network
• Point to point networks consists of many connections between individual pairs of
machines. To go from the source to the destination a packet on these types of
network may have to go through intermediate computers before they reach the
desired computer.
• Often the packets have to follow multiple routes, of different lengths.
• Hence routing algorithms are very important in the point-to-point networks.
• An important general rule is as follows:
Small, localized networks (e.g. LAN) tend to use the broadcasting; whereas networks
located over wide geographical areas (such as WAN) use point-to-point
transmission.

Network Computing Model
Peer-to-peer
A peer-to-peer (P2P) network is created when two or more PCs are
connected and share resources without going through a separate
server computer.
The peer to peer computing architecture contains nodes that are equal
participants in data sharing. All the tasks are equally divided between
all the nodes. The nodes interact with each other as required as share
resources.

Characteristics of Peer-to-peer
• Peer to peer networks are usually formed by groups of a dozen or less computers.
These computers all store their data using individual security but also share data with
all the other nodes.
• The nodes in peer to peer networks both use resources and provide resources. So, if
the nodes increase, then the resource sharing capacity of the peer to peer network
increases.
• Since nodes in peer to peer networks act as both clients and servers, it is difficult to
provide adequate security for the nodes.
• Most modern operating systems such as Windows and Mac OS contain software to
implement peer to peer networks.

Advantages of Peer-to-peer
• Each computer in the peer to peer network manages itself. So, the network is quite easy
to set up and maintain.
• In the client server network, the server handles all the requests of the clients. This provision
is not required in peer to peer computing and the cost of the server is saved.
• It is easy to scale the peer to peer network and add more nodes. This only increases the
data sharing capacity of the system.
• None of the nodes in the peer to peer network are dependent on the others for their
functioning.

Disadvantages of Peer-to-peer
• It is difficult to backup the data as it is stored in different computer systems and there is
no central server.
• It is difficult to provide overall security in the peer to peer network as each system is
independent and contains its own data.

Client-Server
• In client server computing, the clients requests a
resource and the server provides that resource.
• A server may serve multiple clients at the same time
while a client is in contact with only one server.

Characteristics of Client-server
• The client server computing works with a system of request and response. The client sends a
request to the server and the server responds with the desired information.
• The client and server should follow a common communication protocol so they can easily
interact with each other.
• A server can only accommodate a limited number of client requests at a time. So it uses a
system based to priority to respond to the requests.
• An example of a client server computing system is a web server. It returns the web pages
to the clients that requested them.

Advantages of Client-server
• All the required data is concentrated in a single place i.e. the server. So it is easy to
protect the data and provide authorization and authentication.
• The server need not be located physically close to the clients. Yet the data can be
accessed efficiently.
• It is easy to replace, upgrade or relocate the nodes in the client server model because all
the nodes are independent and request data only from the server.
• All the nodes i.e clients and server may not be build on similar platforms yet they can
easily facilitate the transfer of data.

Disadvantages of Client-server
• If all the clients simultaneously request data from the server, it may get overloaded. This
may lead to congestion in the network.
• If the server fails for any reason, then none of the requests of the clients can be fulfilled.
This leads of failure of the client server network.
• The cost of setting and maintaining a client server model are quite high.

Difference between peer-to-peer and client- server

Distributed
• A distributed system contains multiple nodes that are
physically separate but linked together using the
network.
• All the nodes in this system communicate with each
other and handle processes in tandem.
• Each of these nodes contains a small part of the
distributed operating system software.

Advantages of Distributed Systems
• All the nodes in the distributed system are connected to each other. So nodes can easily
share data with other nodes.
• More nodes can easily be added to the distributed system i.e. it can be scaled as
required.
• Failure of one node does not lead to the failure of the entire distributed system. Other
nodes can still communicate with each other.
• Resources like printers can be shared with multiple nodes rather than being restricted to
just one.

Disadvantages of Distributed Systems
• It is difficult to provide adequate security in distributed systems because the nodes as
well as the connections need to be secured.
• Some messages and data can be lost in the network while moving from one node to
another.
• The database connected to the distributed systems is quite complicated and difficult to
handle as compared to a single user system.
• Overloading may occur in the network if all the nodes of the distributed system try to
send data at once.

Network Operating System
• Network operating system is like a software that is installed on the server side on the
network infrastructure.
• The basic definition of an operating system is that the operating system is the interface
between the computer hardware and the user.
• The primary purpose of the network operating system is to allow shared file and printer
access among multiple computers in a network, typically a local area network (LAN), a
private network or to other networks.
Novell NetWare was introduced as a first network operating system, in 1983.

Functions Of Network Operating System
Functions of the NOS :
• Creating and managing user accounts on the network.
• Controlling access to resources on the network.
• Provide communication services between the devices on the network.
• Monitor and troubleshoot the network.
• Configuring and Managing the resources on the network.

Types of Network Operating System
There are two basic types of network operating systems, the
• Peer-to-peer NOS and
• The client/server NOS

Peer-to-Peer Network operating System
• Peer-to-peer network operating systems allow sharing resources and files
with small-sized networks and having fewer resources.
• In general, peer-to-peer network operating systems are used on LAN.

Client/Server Network Operating System
• Client-server network operating systems provide users access to resources
through the central server.
• This NOS is too expensive to implement and maintain.
• This operating system is good for the big networks which provide many
services.

Features Of Network Operating System
•Printers and application sharing on the network.
•File systems and database sharing.
•Provide good security by using functionality like user authentication and access
control.
•Create backups of data.
•Inter-networking.

Examples of Network Operating System
Examples of network operating systems include
• Microsoft Windows Server 2003,
• Microsoft Windows Server 2008,
• UNIX,
• Linux,
• Mac OS X,
• Novell NetWare, and
• BSD.