1. The document discusses the components of a data communication system including the message, sender, receiver, transmission medium, and protocols. 2. It describes the five main components: the message being communicated, the sender who transmits the message, the receiver that receives the message, the transmission medium like cables or wireless that connects the sender and receiver, and the set of protocols that govern the communication. 3. It also discusses different network types like LAN, PAN, MAN, and WAN and provides examples to explain each type.

1. Assignment
On
CourseTitle: data
communication
Course code: CSE-313
Submitted to:
Pranab Bandhu Nath
Lecturer
Department of CSE

2. City University
Khagan, Savar, Dhaka
Submitted by:
Md .R0biul islam
ID: 1834902090
Batch:49th
Program:CSE(Day)
Department of CSE
City University
Khagan,savar,Dhaka

3. Assignment no :1
Assignment name : class
Lecture Notes 1
Components of Data
Communication System
Data Communication is
defined as exchange of data
between two devices via
some form of transmission
media such as a cable, wire
or it can be air or vacuum
also. For occurrence of data
communication,

4. communicating devices
must be a part of
communication system
made up of a combination of
hardware or software
devices and programs.
Data Communication
System Components :
There are mainly five
components of a data
communication system:
1. Message
2. Sender
3. Receiver
4. Transmission Medium
5. Set of rules (Protocol)

5. All above mentioned
elements are described
below:
Figure – Components of
Data Communication
System

6. 1. Message :
This is most useful asset of
a data communication
system. The message
simply refers to data or
piece of information which
is to be communicated. A
message could be in any
form, it may be in form of a
text file, an audio file, a
video file, etc.
2. Sender :
To transfer message from
source to destination,

7. someone must be there who
will play role of a source.
Sender plays part of a
source in data
communication system. It
is simple a device that
sends data message. The
device could be in form of
a computer, mobile,
telephone, laptop, video
camera, or a workstation,
etc.
3. Receiver :
It is destination where
finally message sent by
source has arrived. It is a

8. device that receives
message. Same as sender,
receiver can also be in form
of a computer, telephone
mobile, workstation, etc.
4. , Transmission medium
In entire process of data
communication, there must
be something which could
act as a bridge between
sender and receiver,
Transmission medium
plays that part. It is
physical path by which data
or message travels from
sender to receiver.

9. Transmission medium
could be guided (with
wires) or unguided (without
wires), for example, twisted
pair cable, fiber optic cable,
radio waves, microwaves,
etc.
5. Set of rules (Protocol) :
To govern data
communications, various
sets of rules had been
already designed by the
designers of the
communication systems,
which represent a kind of
agreement between

10. communicating devices.
These are defined as
protocol. In simple terms,
the protocol is a set of rules
that govern data
communication. If two
different devices are
connected but there is no
protocol among them, there
would not be any kind of
communication between
those two devices. Thus the
protocol is necessary for
data communication to take
place

11. Networks (Simplex, Half-
Duplex and Full-Duplex)
Transmission mode means
transferring data between
two devices. It is also
known as a communication
mode. Buses and networks
are designed to allow
communication to occur
between individual devices
that are interconnected.
There are three types of
transmission mode:-

12. These are explained as
following below.
1. Simplex Mode –
In Simplex mode, the
communication is
unidirectional, as on a one-
way street. Only one of the
two devices on a link can
transmit, the other can only
receive. The simplex mode

13. can use the entire capacity
of the channel to send data
in one direction.
Example: Keyboard and
traditional monitors. The
keyboard can only introduce
input, the monitor can only
give the output.
2. Half-Duplex Mode –
In half-duplex mode, each
station can both transmit
and receive, but not at the

14. same time. When one device
is sending, the other can
only receive, and vice versa.
The half-duplex mode is
used in cases where there is
no need for communication
in both directions at the
same time. The entire
capacity of the channel can
be utilized for each
direction.
Example: Walkie-talkie in
which message is sent one at
a time and messages are sent
in both directions.

15. Channel
capacity=Bandwidth *
Propagation Delay
3. Full-Duplex Mode –
In full-duplex mode, both
stations can transmit and
receive simultaneously. In
full_duplex mode, signals
going in one direction share
the capacity of the link with
signals going in another

16. direction, this sharing can
occur in two ways:
 Either the link must contain
two physically separate
transmission paths, one for
sending and the other for
receiving.
 Or the capacity is divided
between signals travelling
in both directions.
Full-duplex mode is used
when communication in
both directions is required
all the time. The capacity of
the channel, however, must

17. be divided between the two
directions.
Example: Telephone
Network in which there is
communication between
two persons by a telephone
line, through which both can
talk and listen at the same
time.
Channel Capacity=2*
Bandwidth*propagation
Delay

18. What Is the OSI Model
The Open Systems
Interconnection (OSI)
model describes seven
layers that computer
systems use to communicate
over a network. It was the
first standard model for
network communications,
adopted by all major
computer and
telecommunication
companies in the early
1980s

19. The modern Internet is not
based on OSI, but on the
simpler TCP/IP model.
However, the OSI 7-layer
model is still widely used,
as it helps visualize and
communicate how networks
operate, and helps isolate
and troubleshoot networking
problems.
OSI was introduced in 1983
by representatives of the
major computer and telecom
companies, and was adopted
by ISO as an international
standard in 1984.

22. We’ll describe OSI layers
“top down” from the
application layer that
directly serves the end
user, down to the physical
layer.
7. Application Layer
The application layer is used
by end-user software such
as web browsers and email
clients. It provides protocols
that allow software to send
and receive). information
and present meaningful data
to users . A few examples of
application layer protocols

23. are the Hypertext Transfer
Protocol (HTTP), File
Transfer Protocol (FTP),
Post Office Protocol (POP),
Simple Mail Transfer
Protocol (SMTP), and
Domain Name System
(DNS).
6. Presentation Layer
The presentation layer
prepares data for the
application layer. It defines
how two devices should
encode, encrypt, and
compress data so it is

24. received correctly on the
other end. The presentation
layer takes any data
transmitted by the
application layer and
prepares it for transmission
over the session layer.
5. Session Layer
The session layer creates
communication channels,
called sessions, between
devices. It is responsible for
opening sessions, ensuring
they remain open and
functional while data is

25. being transferred, and
closing them when
communication ends. The
session layer can also set
checkpoints during a data
transfer—if the session is
interrupted, devices can
resume data transfer from
the last checkpoint.
4. Transport Layer
The transport layer takes
data transferred in the
session layer and breaks it
into “segments” on the
transmitting end. It is

26. responsible for reassembling
the segments on the
receiving end, turning it
back into data that can be
used by the session layer.
The transport layer carries
out flow control, sending
data at a rate that matches
the connection speed of the
receiving device, and error
control, checking if data was
received incorrectly and if
not, requesting it again.
3. Network Layer

27. The network layer has two
main functions. One is
breaking up segments into
network packets, and
reassembling the packets on
the receiving end. The other
is routing packets by
discovering the best path
across a physical network.
The network layer uses
network addresses (typically
Internet Protocol addresses)
to route packets to a
destination node.
2. Data Link Layer

28. The data link layer
establishes and terminates a
connection between two
physically-connected nodes
on a network. It breaks up
packets into frames and
sends them from source to
destination. This layer is
composed of two parts—
Logical Link Control
(LLC), which identifies
network protocols, performs
error checking and
synchronizes frames, and
Media Access Control
(MAC) which uses MAC

29. addresses to connect devices
and define permissions to
transmit and receive data.
1. Physical Layer
The physical layer is
responsible for the physical
cable or wireless connection
between network nodes. It
defines the connector, the
electrical cable or wireless
technology connecting the
devices, and is responsible
for transmission of the raw
data, which is simply a
series of 0s and 1s, while

30. taking care of bit rate
control.
Computer Network Types
A computer network is a
group of computers linked
to each other that enables
the computer to
communicate with another
computer and share their
resources, data, and
applications.
A computer network can be
categorized by their size.

31. A computer network is
mainly of four types:
o LAN(Local Area
Network)
o PAN(Personal Area
Network)
o MAN(Metropolitan Area
Network)
o WAN(Wide Area
Network)

32. LAN(Local Area Network)
o Local Area Network is a
group of computers
connected to each other in
a small area such as
building, office.
o LAN is used for
connecting two or more
personal computers
through a communication
medium such as twisted
pair, coaxial cable, etc.
o It is less costly as it is
built with inexpensive
hardware such as hubs,

33. network adapters, and
ethernet cables.
o The data is transferred at
an extremely faster rate in
Local Area Network.
o Local Area Network
provides higher security.

34. PAN(Personal Area
Network)
o Personal Area Network is
a network arranged within
an individual person,
typically within a range
of 10 meters.
o Personal Area Network is
used for connecting the
computer devices of
personal use is known as
Personal Area Network.
o Thomas
Zimmerman was the first
research scientist to bring

35. the idea of the Personal
Area Network.
o Personal Area Network
covers an area of 30 feet.
o Personal computer
devices that are used to
develop the personal area
network are the laptop,
mobile phones, media
player and play stations.

36. MAN(Metropolitan Area
Network)
o A metropolitan area
network is a network that
covers a larger
geographic area by
interconnecting a
different LAN to form a
larger network.
o Government agencies use
MAN to connect to the
citizens and private
industries.
o In MAN, various LANs
are connected to each

37. other through a telephone
exchange line.
o The most widely used
protocols in MAN are
RS-232, Frame Relay,
ATM, ISDN, OC-3,
ADSL, etc.
o It has a higher range than
Local Area
Network(LAN).

38. Uses Of Metropolitan
Area Network:
o MAN is used in
communication between
the banks in a city.

39. o It can be used in an
Airline Reservation.
o It can be used in a college
within a city.
o It can also be used for
communication in the
military.
WAN(Wide Area
Network)
o A Wide Area Network is
a network that extends
over a large geographical
area such as states or
countries.

40. o A Wide Area Network is
quite bigger network than
the LAN.
o A Wide Area Network is
not limited to a single
location, but it spans over
a large geographical area
through a telephone line,
fibre optic cable or
satellite links.
o The internet is one of the
biggest WAN in the
world.
o A Wide Area Network is
widely used in the field of

41. Business, government,
and education.

43. Examples Of Wide Area
Network:
o Mobile Broadband: A
4G network is widely
used across a region or
country.

44. o Last mile: A telecom
company is used to
provide the internet
services to the customers
in hundreds of cities by
connecting their home
with fiber.
o Private network: A bank
provides a private
network that connects the
44 offices. This network
is made by using the
telephone leased line
provided by the telecom
company.

45. Ip address class:
Class A --- 1 to 126
Class B --- 128 to 191
Class C --- 192 to 223
Class D --- 224 to 239
Class E --- 240 to 255
References
References- Data
Communication and
Network,5th Edition,
Behrouz

46. References
https://www.geeksforgeeks.
org/components-of-data-
communication-system/
References
https://www.imperva.com/le
arn/application-security/osi-
model/
References
https://www.javatpoint.com/
types-of-computer-network