Basic concept of Computer networks Goals of networking, Application of Computer Network, Network Hardware & Software

1. Note 1
Introduction to Computer Networks
Course Title: Computer Networks Theory
Course Code: CSE 317
Submitted To
Pranab Bandhu Nath
Senior Lecturer, Department Of CSE
City University, Dhaka
Submitted By
Hasibul Islam Nirob
ID: 182482526
BSc in CSE (Day)
Batch: 49th

2. What is Computer Network?
A computer network is any group of interconnected computing devices capable of sending
or receiving data. You can establish a network connection using either cable or wireless
media.
Advantages of computer networking:
File sharing - you can easily share data between different users, or access it remotely if
you keep it on other connected devices.
Resource sharing - using network-connected peripheral devices like printers, scanners
and copiers, or sharing software between multiple users, saves money.
Sharing a single internet connection - it is cost-efficient and can help protect your
systems if you properly secure the network.
Increasing storage capacity - you can access files and multimedia, such as images and
music, which you store remotely on other machines or network-attached storage
devices.
Goals of Computer Network:
Resource sharing: is the main objective of the computer network. The goal is to provide
all the program, date and hardware is available to everyone on the network without
regard to the physical location of the resource and the users.
Reliability: The second objective is to provide the high Reliability. It is achieved by
replicating the files on two or more machines, so in case of unavailability (due to fail of
hardware) the other copies can be used.
Scalability: Computer network have provided means to increase system performance as
the work load increases (load balancing). In the days of mainframe when the system
was full it was to replace with the other large mainframe computer, usually at and
expensive rate not convenience for user.
Performance: Another closely related goal is to increase the systems performance as
the work load increases by just adding more processors. With central mainframes, when
the system is full, it must be replaced by a larger one, usually at great expense and with
even greater disruption to the users.
Security: Only authorized user can access resource in a computer network. Users are
authenticated by their username and password. Hence it is not possible to access the
data without proper account. This increases security.

3. Application of Computer Networks
• Business Applications
• Communication Medium
• e-commerce
• Home Applications
• Electronic commerce
• Mobile Users
Network Hardware & Software
There are three components of Computer Network
1. Hardware Equipment
2. Software
3. Cables and Connectors
Hardware Equipment’s
Network Interface Card (NIC):
The interface card which is used to connect one device to another is called Network
interface card or NIC. Nowadays, it is attached to all computer’s motherboard. It has
a unique 48-bit code. This code is called MAC Address.
Modem:
The word Modem is sort form of the words Modulator and Demodulator. Modulator
converts digital signal to analog signal and Demodulator converts analog signal to
Digital signal.
Server:
A server is a computer that provides data to other computers. It may serve data to
systems on a local area network (LAN) or a wide area network (WAN) over the Internet.
Client:
A client is any device that communicates with a server. Businesses have clients
and servers have clients. In both instances, there exists a one-to-many relationship. Just
like a business may have several clients, a server can communicate with multiple clients.
In computer networking, this is called the client-server model.
Peers:
On the same level or providing the same function. In networking, a peer is a node that
provides the same functionality as another. Peer to Peer." In a P2P network, the "peers"
are computer systems which are connected to each other via the Internet. Files can be
shared directly between systems on the network without the need of a central server. In
other words, each computer on a P2P network becomes a file server as well as a client.

4. Transmission:
Data transmission is the process of sending digital or analog data over a communication
medium to one or more computing, network, communication or electronic devices. It
enables the transfer and communication of devices in a point-to-point, point-to-
multipoint and multipoint-to-multipoint environment
Medium:
A medium is a third-party or element through which a message is communicated. This
seems to apply to information technology as well as to seances. In information
technology, a medium can be:
1. A physical transmission medium such as optical fiber
2. A presentation medium (and thus the terms multimedia and advertising
media)
Router: Network routing is the process of selecting a path across one or more networks.
The principles of routing can apply to any type of network, from telephone networks to
public transportation. In packet-switching networks, such as the Internet, routing selects
the paths for Internet Protocol (IP) packets to travel from their origin to their
destination.
Bridge:
A bridge operates at data link layer. A bridge is a repeater, with add on the functionality
of filtering content by reading the MAC addresses of source and destination. It is also
used for interconnecting two LANs working on the same protocol. It has a single input
and single output port, thus making it a 2-port device.
Types of Bridges
Transparent Bridges: These are the bridge in which the stations are completely
unaware of the bridge’s existence i.e., whether or not a bridge is added or
deleted from the network, reconfiguration of the stations is unnecessary. These
bridges make use of two processes i.e., bridge forwarding and bridge learning.
Source Routing Bridges: In these bridges, routing operation is performed by
source station and the frame specifies which route to follow. The host can
discover frame by sending a special frame called discovery frame, which spreads
through the entire network using all possible paths to destination.

5. Hub:
A hub is basically a multiport repeater. A hub connects multiple wires coming from
different branches, for example, the connector in star topology which connects different
stations. Hubs cannot filter data, so data packets are sent to all connected devices
Types of Hub
Active Hub: These are the hubs which have their own power supply and can
clean, boost, and relay the signal along with the network. It serves both as a
repeater as well as wiring center. These are used to extend the maximum
distance between nodes.
Passive Hub: These are the hubs which collect wiring from nodes and power
supply from active hub. These hubs relay signals onto the network without
cleaning and boosting them and can’t be used to extend the distance between
nodes.
Intelligent Hub: It work like active hubs and include remote management
capabilities. They also provide flexible data rates to network devices. It also
enables an administrator to monitor the traffic passing through the hub and to
configure each port in the hub.
Switch:
Switch is a network device that connects other devices to ethernet networks
through twisted pair cables. It uses packet switching technique to receive,
store and forward data packets on the network. The switch maintains a list of
network addresses of all the devices connected to it
Gateway:
Gateway is a network device used to connect two or more dissimilar networks. In
networking, networks that use different protocols are dissimilar networks. A
gateway usually is a computer with multiple NICs connected to different networks.
A gateway can also be configured completely using software.
Wi-Fi Card:
Wi-Fi is the acronym for wireless fidelity. Wi-Fi technology is used to achieve wireless
connection to any network. Wi-Fi card is a card used to connect any device to the local
network wirelessly. The physical area of the network which provides internet access
through Wi-Fi is called Wi-Fi hotspot.
Repeater: A repeater operates at the physical layer. Its job is to regenerate the signal
over the same network before the signal becomes too weak or corrupted so as to

6. extend the length to which the signal can be transmitted over the same network. An
important point to be noted about repeaters is that they do not amplify the signal.
When the signal becomes weak, they copy the signal bit by bit and regenerate it at the
original strength. It is a 2-port device.
Software:
• Network Operating System,
• Protocols Switches (TCP/IP, OSI)
• Client Software
Cables and Connectors:
• Twisted pair cable
• Coaxial cable
• Fiber-optic cable
References
https://whatis.techtarget.com/definition/medium
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https://www.guru99.com/basic-computer-network.html#1
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networks#:~:text=Advantages%20of%20computer%20networking&text=Resource%20sharing%
20%2D%20using%20network%2Dconnected,you%20properly%20secure%20the%20network.
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https://www.ques10.com/p/9412/what-is-a-network-what-are-its-goals-and-applica-1/
https://techterms.com/definition/server
https://techterms.com/definition/nic
https://techterms.com/definition/client
https://www.pcmag.com/encyclopedia/term/peer
https://techterms.com/definition/p2p
https://www.techopedia.com/definition/9756/data-transmission
https://www.geeksforgeeks.org/network-devices-hub-repeater-bridge-switch-router-
gateways/
https://en.wikipedia.org/wiki/Gateway_%28telecommunications%29
https://en.wikipedia.org/wiki/Router_%28computing%29
https://en.wikipedia.org/wiki/Network_switch