Illustrate this Basic concept of Computer networks and distributed systems, Goals of networking, General approaches of communication within a network, Network classification, Uses & Network Software

1. City University
Course Title: Computer Networks
Course Code: CSE317
Topic Name: Illustrate this Basic Concept of Computer networks and
Distributed Systems, Goals of networking, General Approaches of
Communication
within a Network, Network classification, Uses & Network Software.
Submitted By
Nishat Tasnim Ali
ID:1834902591
Batch: 49th
Submitted To
Pranab Bandhu Nath
Senior Lecturer
Department of CSE
City University

2. Computer Networks
A computer network is a network between computers which connects
multiple computers in a manner to enables meaningful transmission and
exchange of data among them.
Sharing of information (both hardware and software) and processing
load is the main objective of a computer network.
Goals of Computer Network
1. Resource sharing: All programs, data and equipment (printers, hard
disks, plotters) available to anyone on the network without the
regard of physical location of the resource and the user.
2. High reliability: Having alternative sources of supply during
hardware failure can provide high reliability.
3. Performance: It is measured in terms of transit time and respond
time. Performance of a computer network depends on type of
transmission medium, capability of connected network, number of
users, efficiency of software.
4. Scalability: Network must be scalable so that it can be extended by
adding new devices.
5. Security: It means protecting data from unauthorized access.
Network allows security to ensure the right to access the certain
data to the users.
Components of Computer Network
1. Hardware :
i. NIC (Network Interface Card): It is a hardware device
that connects a computer to a network both functionally
and physically. The main purpose of NIC is to format
data, send and receive data at receiver node.

3. ii. Server: These are the computers that holds data that can
be shared over a computer network. It also runs
operating system.
iii. Client: It is a computer that can receive data from the
other computers in computer network.
iv. Transmission Media: In computer network computers
are connected by transmission medium such as wire,
cables etc.
v. HUB: It is a physical layer networking device that connects all the
computer in a network with each other. It works as a central connection
for all the devices that are connected through a hub. Hub has numerous
ports. Hub cannot filter data so data packets are sent to all the computers
that are connected with hub. Hub isn’t capable of storing MAC
addresses. The speed of hub network is up to 10 Mb per second.
Advantages:
 It can easily connects different media types.
 Anyone can use it as it is very cheap.
 It can extend the distance of the network.
 Doesn’t impact on network performance.
 Good for sharing same data.
Disadvantages:
 A network hub has no intelligence.
 It cannot reduce network traffic as it has no mechanism.
 As it can’t filter data and send them to all the devices that are
connected to it; it has no security.
Applications:
 Small home networks.
 Network monitoring.
 Provide connectivity in organizations.

4. vi. Switch: A switch is a data link layer device which connects multiple
devices within a network. It can perform error checking before
forwarding data. It can manage physical network as well as software
based virtual devices. It uses MAC addresses to send data packets to
selected destination ports. It uses packet switching technique to receive
and forward data from source to destination ports.
Advantages:
 It is an intelligent network device that can be conceived as a
multiport network bridge.
 It support unicast, multicast and broadcast communication.
 Transmission mode is full duplex.
 Have network software and network management capabilities.
 More secure.
 Increase the bandwidth of the network.
Disadvantages:
 They are more costly.
 Broadcast traffic might be problematic.
 They are defenseless against security assaults like catching
Ethernet outlines.
 Must have physical contact with the object to be actuated.
vii. Router: It is a networking device that forwards data packets between
computer networks. It can be connected to two or more data lines from
different IP networks. When a data packet comes in one of the lines,
router reads the address information from the packet header and
determine the destination. Router uses modem to connect devices and
the internet.
Advantages:
 It can choose bet path across the internetworking.
 It reduces network traffic.

5.  It provides sophisticated routing and flow control.
Disadvantages:
 They are expensive compare to other network devices like hub,
switches.
 They are slower as they have to analyze data.
 Require amount of initial configurations.
Viii. Bridge: It is a network device that connects multiple LAN together
to form a larger LAN. It uses forwarding database or bridge table.
Advantages:
 For some individual nodes bridge increases network bandwidth.
 It reduce network congestion by dividing LAN into small
segments.
 It has higher levels of protocol transparent.
Disadvantages:
 Bridge cost more than hubs and repeaters.
 It cannot filter the broadcast traffic individually.
 As it view all the MAC addresses, they have downgrade
performance.
ix. Repeater: It is a network device that retransmit the data from the
sender to the receiver side of the network.
Advantages:
 It is less costly than other network device.
 The performances are good.
 It has the facility to extend the length of transmission.
Disadvantages:
 Network traffic.
 Increase the possibilities of packet collision.

6.  It cannot create separate traffic from one cable to a special.
x. Gateway: It is a networking device that enables two different
networks to communicate with each other that connects two different
networks together enable to communicate with each other.
Advantages:
 Expand the network.
 Connect two different types of network.
 Effectively handles the traffic.
Disadvantages:
 Not an intelligent device.
 It doesn’t filter data.
 Costly.
 Transmission rate is slower.
2. Software:
i. Operating System: It facilitate workstation in Network a network
to share files, database, printers etc.
ii. Protocol Suite: It is a guideline or rule followed by computers
for data communication. Two popular protocol suite are-
 OSI Model
 TCP/IP Model
3. Cables and Connections:
I. Twisted Pair Cable: It is also known as Ethernet cable.
Generally used in LAN computer networks. It is a
combination of two separate insulated copper wires twisted
together and run in parallel.
II. Coaxial Cable: It carries high frequency electrical signals
with low losses. It is used in broadband internet networking
cables, cable television signals etc.

7. III. Fiber Optic Cable: It is an electrical cable that contain one or
more optic fibers that are used to carry light. It is used for
long distance telecommunication, high speed data
connection etc. Thus it needs high maintenance. It is
expensive.
Distributed System: ARPANET
ARPANET was the first technical foundation for INTERNET. It is the
earliest example of a large scale distributed application. The Advanced
Research Projects Agency Network (ARPANET) was the first wide area
packet switching network with distributed control and one of the first
networks to implement the TCP/IP Protocol Suite.
It was developed under the direction of the U.S. Advanced Research
Projects Agency (ARPA) in 1967. In 1969 it become reality with the
interconnection of four university computers.
The initial purpose was to communicate with and share computer
resources among mainly scientific user at the connected institutions.
The development of TCP/IP protocols in 1970s made it possible to
expand the size of the network. In the 1980s, ARPANET was handed
over to a separate new military network, NSFNET. In 1995, NFSNET
turn the backbone of the INTERNET over to commercial backbone
providers.
General Approaches of Communication
within a Network
There are two main approaches of communication in network:
1. Client-Server Network: The server provide the access of resources
such as Web pages, databases etc. to other nodes (client) on the
network.

8. 2. Peer-to-Peer Network: Nodes have equal authority and act as
client-server both such as popular games, movies, music etc.
Classification of Network
1.PAN: Personal Area Network is a network that interconnects
devices within an individual person’s workspace. The range is only
10 meter. PAN is used for connecting devices like personal
computer, mobile phone, laptop, play stations etc. PAN is
developed simply by using WIFI, Bluetooth and USB. Generally it
is used at home, home offices or body area network.
2.LAN: Local Area Network is a group of computers that are
connected to each other in a small area. The range of LAN is up to
1km. Star, ring topologies are used in LAN. LAN are used for data
processing, data entry and email system. It use twisted pair cable,
coaxial cable etc.as communication medium. It is less costly and
provides higher security. Data transfer rate is faster in LAN.
Generally used in offices, schools, buildings etc.
3.MAN: Metropolitan Area Network is a network that interconnects
devices in a different LAN to form a larger network that can cover
a larger geographical area. The range is up to 10 km. In MAN,
different LANs are connected to each other through a telephone
exchange line. Generally MAN is used in communication between
banks, colleges, airline reservation within a city.
4.WAN: Wide Area Network is a network that extends over a large
geographic area like state or countries. It is not limited to single
location but over a large geographic area through telephone line,
fiber optic cable or satellite links.
Internet is the biggest WAN network. WAN is also used in Mobile
Broadband, Last mile, Private network.

9. Network Software
Network software is a set of tools that helps computers to share
information with others or allow to share computer programs. Example:
Client-Server program.
Function of Network Software
1. Enables network virtualizations.
2. Allow administrations to add or remove users.
3. It helps to set up and install computer networks.
4. Allow users to access data and network resources.
SDN Framework
Network Framework has three layers:
1) Application Layer: It contains network applications such as
routing, firewall, load balancing etc.
2) Control Layer: It consists SDN controller which allow hardware
abstraction to the application written on the top of it.
3) Infrastructure Layer: It consists physical switches that forms data
plane and carries out actual movement of data packets.
Layers communication via network interfaces are called
northbound and southbound APIs.
Northbound APIs
Southbound APIs
Fig: Structure of SDN
Application Layer
Control Layer
Infrastructure Layer

10. System Software
System software includes the programs that are dedicated to managing
the computer itself such as operating system, file management utilities
and also controls monitors, printers and storage devices.
Application Software
A software that helps the user to perform specific tasks is called
application software. Example: Firefox, Excel, Word, PowerPoint,
Skype etc.
Software
It is the program and routine for a computer or an electronic device
which make it run. Example: Excel, Windows etc.
Hardware
It is the physical elements of a computer or a system. Example:
Keyboard, Mouse, Monitor and CPU.
Firmware
It is a semi-permanent software program or set of instructions
programmed on a hardware. Example: Embedded Systems.
App
App is a software that used on smart phones or mobile devices or
computers or other electronic devices that perform a specific function
directly for the user or other application program. Example: Microsoft
Word.

11. Difference between Application software & System
Software
Application Software System Software
1. It runs on the platform which is
provided by system software as
per user request.
1. It is the interface between
application software and system.
2. It is used by users to perform
specific tasks.
2. It is used for operating
computer hardware.
3. It can’t run independently
without the presence of system
software.
3. It can run independently.
4. They are developed in high
level language as for some
specific purpose software.
4. They are developed in low level
language.
5. It runs as per the user’s request 5. It runs when system is turned
on and stop when system is turned
off.
Difference between App & software
App Software
1. It is a software that does a
certain task.
1. It is a program that make
computer or other electronics device
run.
2. They are executable. 2. They may or may not be
executable.
3. Need user interaction. 3. No or less user interaction.
4. All the apps are software. 4. All the software aren’t apps.
5. It is used only by end users. 5. It is used as mediator between
user and hardware.

12. 6. Example: Microsoft Word,
Adobe Photoshop, Duo lingo etc.
6.Example: Google Chrome, Opera,
Firefox etc.
Difference between Hardware, Software & Firmware
Hardware Software Firmware
1. It is the physical
elements of a
computer or a system.
1. It is the program
and routine for a
computer or an
electronic device
which make it run.
1. It is a semi-
permanent software
program or set of
instructions
programmed on a
hardware.
2. Can be updated
least often.
2. Can be updated
often by users.
2. May not be updated
often.
3. Hardware is the
most permanent
physical components.
3. Software is the
most temporary.
3. Firmware is semi-
permanent software.
4. It can’t be changed
but replaceable.
4. It can be easily
changed constantly.
4. It can be rarely
changed.
5. Software or
Firmware runs on
hardware.
5. Software is the set
of instruction on
hardware.
5. Firmware is a
special kind of
software that only do
specific tasks.
6. Example:
Keyboard, Monitor,
Mouse, CPU, RAM.
6. Example: Internet
Browsers, Operating
System, Antiviruses.
6. Example: Basic
Input/output System
(BIOS), Extensible
Firmware Interface
(EFI).
Addressing
There are 4 types of addresses:
 Physical Addresses: MAC
 Logical Addresses: IP Address

13.  Port Addresses: TCP/IP protocol suite.
 Application Special Addresses: URL
IP Address
An Internet Protocol (IP) address is a numerical label assigned to device
that connected to the computer network that uses the IP for
communication.
Every IP address divided into two parts:
 Network ID: It is the number of networks.
 Host ID: It is the number of hosts.
Types of IP Address
 Public: IP address that provided by ISP to routers.
 Private: Bluetooth devices, printers etc.
 Static: Static IP addresses are consistent, which is assigned once,
that stays the same over the years.
 Dynamic: Dynamic IPs can trace their origin to a collection of IP
addresses that are shared across many computers.
Class of IP Addressing
1. Class A: Range is 1.0.0.0 to 126.255.255.255
2. Class B: Range is 128.0.0.0 to 191.255.255.255
3. Class C: Range is 192.0.0.0 to 223.255.255.255
4. Class D: Range is 224.0.0.0 to 239.255.255.255
5. Class E: Range is 240.0.0.0 to 255.255.255.255
 Here 127.255.255.255 is known as Loop Back Address.