Computer networks allow two or more computers to connect and communicate electronically for sharing resources and data. The key goals of networking include resource sharing, high performance, reliability, inter-process communication, security, and flexible access to files from any computer on the network. Computer networks have hardware components like network interface cards, servers, clients, and transmission media, as well as software including network operating systems and protocols. Cables that connect the hardware include twisted pair, coaxial, and fiber-optic cables.

1. CITY UNIVERSITY
Faculty of Science and Engineering
Department of Computer Science and Engineering
Spring 2021
CSE 317 Computer Network
First Class
Introduction to Computer Networks:
Basic concept of Computer networks Goals of networking
Submitted To
Pranab Bandhu Nath
Senior Lecturer
Department of CSE
City University
Submitted By
Najmul Islam
1834902556

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What is Computer Network ?
 Computer network, two or more computers that are connected
with one another for the purpose of communicating data
electronically. It is a system in which multiple computers are
connected to each other to share information and resources.
Characteristics of a Computer Network
 Share resources from one computer to another.
 Create files and store them in one computer, access those files
from the other computers connected over the network.
 Connect a printer, scanner, or a fax machine to one computer
within the network and let other computers of the network use
the machines available over the network.

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Goals of Computer Network
1. Resource Sharing –
Many organization has a substantial number of computers in
operations, which are located apart. Ex. A group of office workers
can share a common printer, fax, modem, scanner, etc.
2. Performance – It is measured in terms of transit time and
response time by measuring the speed of data transmission with
number of users, connectivity and the software used .
 Transit time is the time for a message to travel from one device to
another
 Response time is the elapsed time between an inquiry and a
response.
3. High Reliability –
If there are alternate sources of supply, all files could be
replicated on two or more machines. If one of them is not
available, due to hardware failure, the other copies could be used.
4. Inter-process Communication –
Network users, located geographically apart, may converse in an
interactive session through the network. In order to permit this,
the network must provide almost error-free communications.
5. Security – It means protecting data from unauthorized access.
It is the main characteristics of Computer network where you can take
necessary steps for protecting your data from unauthorized access
6. Flexible access –
Files can be accessed from any computer in the network. The
project can be begun on one computer and finished on another.

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Application of Computer Network
• Business Applications
• Communication Medium
• e -commerce
• Home Applications
• Electronic commerce
• Mobile Users

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Network Hardware & Software
There are three component of Computer Network
1. Hardware Equipment
2. Software
3. Cables and Connectors
Hardware
NIC: A network interface card (NIC) is a hardware component without
which a computer cannot be connected over a network. It is a circuit
board installed in a computer that provides a dedicated network
connection to the computer. It is also called network interface
controller, network adapter or LAN adapter.
Server: A server is a computer that serves information to other
computers. These computers, called clients, can connect to
a server through either a local area network or a wide area network,
such as the internet.
Client: In a network a desktop computer or workstation that is capable
of obtaining information and applications from a server.
Peers: A peer is a node that provides the same functionality as another.
For example, two desktop PCs in a network are peers. A desktop PC
and a server are not peers as they perform different operations.
Transmission Medium: Transmission media is a communication
channel that carries the information from the sender to the receiver.
Router: Routers guide and direct network data, using packets that
contain various kinds of data—such as files, communications, and
simple transmissions like web interactions.
Bridge: A bridge is a network device that connects multiple LANs
(local area networks) together to form a larger LAN. The process of

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aggregating networks is called network bridging. A bridge connects the
different components so that they appear as parts of a single network.
Bridges operate at the data link layer of the OSI model and hence also
referred as Layer 2 switches.
Hub: A hub is a physical layer networking device which is used to
connect multiple devices in a network.
Switches: A switch is a device in a computer network that connects
other devices together. Multiple data cables are plugged into
a switch to enable communication between different networked
devices.
Gateway: A gateway is a hardware device that acts as a "gate"
between two networks. It may be a router, firewall, server, or other
device that enables traffic to flow in and out of the network.
Repeaters: A repeater is an electronic device that receives a signal
and retransmits it. Repeaters are used to extend transmissions so that
the signal can cover longer distances or be received on the other side
of an obstruction.
Software
Network Operating System : A network operating
system (NOS) is a computer operating system (OS) that is designed
primarily to support workstations, personal computers and, in some
instances, older terminals that are connected on a local
area network (LAN)
Protocols Switches (TCP/IP, OSI): Networking properties such as
total order or recovery from message loss can be realized by many
different protocols. These protocols offer the same functionality but
are optimized for different environments or applications. Hybrid
protocols can be used to combine the advantages of various protocols,
but designing

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Cables and Connectors
Twisted pair cable: Twisted pair cabling is a type of wiring in which
two conductors of a single circuit are twisted together for the purposes
of improving electromagnetic compatibility. Twisted-pair cable is a
type of cabling that is used for telephone communications and most
modern Ethernet networks. A pair of wires forms a circuit that can
transmit data. The pairs are twisted to provide protection against
crosstalk, the noise generated by adjacent pairs
Coaxial cable: Coaxial cable is a type of copper cable specially built
with a metal shield and other components engineered to block signal
interference. It is primarily used by cable TV companies to connect
their satellite antenna facilities to customer homes and businesses.
Fiber-optic cable: A fiber optic cable is a network cable that contains
strands of glass fibers inside an insulated casing. They're designed for
long-distance, high-performance data networking, and
telecommunications. Compared to wired cables, fiber optic
cables provide higher bandwidth and transmit data over longer
distances.

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