Introduction to data communication, TCP/IP protocol suite ,OSI reference model ,logical connections between layers of the TCP/IP Protocol suite ,encapsulation and decapsulation, data and signals ,signal impairment, data modulation

1. Assignment
On
Class notes
Course title : Data communication
Course code : CSE 313
Submitted to
Pranab bandhu nath
Senior Lecturer
Department of CSE
City University
Submitted by
Somaya akter
ID : 1834902142
Batch: 49th
(B)
Department of CSE
City University
Submission date :06.09.2021

2. Data communication
Exchange of data between two devices via some forms of transmission medium is data
communication.
Transmission media
It is the physical path by which a message travels from sender to receiver. Some examples include
twisted-pair wire, coaxial cable, radio waves etc.
Guided media are the physical links through which signals are confined to narrow path. These are
also called guide media. Bounded media are made up o a external conductor (Usually Copper)
bounded by jacket material.Bounded media are great for LABS because they offer high speed, good
security and low cast. However, sometime they cannot be used due distance communication.
Three common types of bounded media are used of the data transmission.
 Coaxial Cable
 Twisted Pairs Cable
 Fiber Optics Cable
Coaxial cable
Coaxial cable is very common & widely used commutation media. For example TV wire is usually
coaxial. Coaxial cable gets its name because it contains two conductors that are parallel to each
other. The center conductor in the cable is usually copper. The copper can be either a solid wire or
stranded martial.
Outsidethis central Conductor is a non-conductive material. It is usuallywhite, plasticmaterial used
to separate the inner Conductor form the outer Conductor. The other Conductor is a fine mesh
made from Copper.
Guided transmission
medium
Unguidedtransmission
medium
Transmission
media

3. Fiber optic cable
Fiber optic cable uses electrical signals to transmit data. It uses light. In fiber optic cable light only
moves in one direction for two way communication to take place a second connection must be
made between the two devices. It is actually two stands of cable. Each stand is responsible for one
direction of communication. A laser at one device sends pulse of light through this cable to other
device. These pulses translated into “1’s” and “0’s” at the other end.
In the center of fiber cable is a glass stand or core. The light from the laser moves through this glass
to the other device around the internal core is a reflective material known as CLADDING. No light
escapes the glass core because of this reflective cladding.
The most popular network cabling is Twisted pair. It is light weight, easy to install, inexpensive and
support many different types of network. It alsosupports the speed of 100mps.Twisted pair cabling
is made of pairs of solid or stranded copper twisted along each other.
There are two types of twisted pairs cabling
1. Unshielded twisted pair (UTP)
2. Shielded twisted pair (STP)
Unshielded twisted pair (UTP)
UTP is more common. It can be either voice grade or data grade depending on the condition. UTP
cable normally has an impedance of 100 ohm. UTP cost less than STP and easily available due to its
many use. There are five levels of data cabling
Shielded twisted pair (STP)
It is similar to UTP but has a mesh shielding that’s protects it from EMI which allows for higher
transmission rate.
Unguided Media
Unguided media or wireless media doesn't use any physical connectors between the two devices
communicating. Usually the transmission is send through the atmosphere but sometime it can be
just across the rule. Wireless media is used when a physical obstruction or distance blocks are used
with normal cable media.
The three types of wireless media are:
 Radio waves

4.  Micro waves
 Infrared waves
OSI model
The OSI model (open systems interconnection model) is a conceptual framework used to describe
the functions of a networking system.
Application
Presentation
Session
Transport
Network
Data link
Physical
Working procedure of OSI Model layers
Application – compose data for sending using some protocol (http,FTP)
Presentation – Encryption
Session – net bios,remote devices
Transport – data divided some packet
Network - IPV4,IPV6,Routing
Data link – MAC ,media access control
Physical – Hardware specification
TCP/IP Model

5. TCP(Transmission IP ( Internet protocol)
control protocol)

6. The TCP/IP Model is a concise version of the OSI model.It contains 5 layers,unlike seven layers in
the OSI model.
TCP/IP Model
Application(Application,
presentation, session)
Host to Host
Internet
Network access memory (data
link layer,physical)
The Open systems interconnection model is a conceptual mode . During working TCP/IP model
,here works some protocol like
Application layer – DNS,BOOTP,DHCP,FTP etc.
Transport layer – UDP,TCP etc Internet layer – NAT,RIP etc
Network access layer – PPP, ethernet, interface drivers
The protocol that make up TCP/IP define
 How data is transmitted across a network
 How data should be formatted so other Network system can understand it.
 Two key TCP/IP feature supports
 End node verification
 Dynamic routing

7. Network issue
 Addressing
 Routing
 Name resolution
 Flow and error control
 Inter operability
Encapsulation and decapsulation
The data which should be transmitted to a new location should go through each layer. When
reaching each layer, the information is added to the data. It is called encapsulation. When the data
reaches the destination, in each layer the added information is unpacked. That process is known as
decapsulation.
Analog data
Analog data is data that is represented in a physical way.
Digital data
Digital data is data that represents other forms of data using specific machine language
systems that can be interpreted by various technologies.
Signal
Signals are the electric or electromagnetic impulses used to encode and transmit data.
In data communication, we are use two type of signals :
Signal
Analogsignal Digital signal

8. Analog signal
An analog signal are continuous and passes through or includes an infinite number of continuous
values along its path. The curve representing the Analog signal passes through an infinite number
of points.
Digital signal
A digital signal can have only a limited number of defined values. Although each value can be any
number,it is as simple as 1 and 0.
Frequency
Frequency is the number of occurrences of a repeating event per unit of time.
Time period
A time period (denoted by 'T'' ) is the time taken for one complete cycle of vibration to pass a given
point.

9. Phase shift
Phase shift simply means that the two signals are at different points of their cycle at a given time.
Phase shift is measured as the angle (in degrees or radians) between two points on a circle at the
same time, demonstrating the progress of each wave through its cycle.
Wavelength
Wavelength is the distance between consecutive corresponding points of the same phase on the
wave.
Bit rate
Bit rate (also called bitrate, data rate, or R) is how fast bits move from one place to another. It is
measured in bits per second.
Transmission impairment
It means that signals that are transmitted at the beginning of the medium are not the same as the
signals that are received at the end of the medium that is what is sent is not what is received.
Attenuation
Attenuation means a loss of energy. When a signal or composite,travels through a medium ,it loses
some of its energy in overcoming the resistance of the medium.That is why a wire carrying
electronic signals gets warm.
Distortion
It occurs when signal shape has been changed.
Noise
Noise is another cause of impairment.
Transmission
impairment
Attenuation Distortion Noise

10. Several types of Noise,such as thermal Noise,induced Noise,cross talk and impulse Noise may
corrupt the signal.
Data communication between different devices are broadly categorised into3 types:
• Simplex communication
• Half- duplex communication and
• Full-duplex communication.
Simplex communication
Simplex communication is a communication channel that sends information in one direction
Only.
Half- duplex communication
Half-duplex devices can only transmit in one direction at one time. With half-duplex mode, data
can move in two directions, but not at the same time.
Full-duplex
Full-duplex devices can only transmit in one direction at one time. With half-duplex mode, data
can move in two directions and at the same time.
Intranet
An intranet is a computer network for sharing information, collaboration tools, operational
systems, and other computing services within an organization, usually to the exclusion of access by
outsiders.Intranet is a private network.
Internet

11. The Internet is a wide network of computers that is available to all whereas Intranet is a network
of computers designed for a certain group of users. Internet is a public network .
Key Differences between Internet and Intranet
The Internet is a global system of computer networks available for everyone, whereas Intranet is a
network of computers owned by any organization for a certain group of people. The Internet is a
public network, while Intranet is a private network.
Mac address
MAC Address stands for Media Access Control Address.(Media Access Control address) The unique
48-bit serial number in the network circuitry of every Ethernet and Wi-Fi device. The MAC address,
which holds 256 trillion unique numbers, identifies that device from every other globally.
NIC
A network interface controller (NIC, also known as a network interface card, network adapter, LAN
adapter or physical network interface, and by similar terms) is a computer hardware component
that connects a computer to a computer network.
A computer network is mainly of four types:
 LAN(Local Area Network)
 PAN(Personal Area Network)
 MAN(Metropolitan Area Network)
 WAN(Wide Area Network)
PAN(Personal Area Network)
A personal area network (PAN) connects electronic devices within a user's immediate area. The size
of a PAN ranges from a few centimeters to a few meters. One of the most common real- world
examples of a PAN is the connection between a Bluetooth earpiece and a smartphone.

12. LAN(Local Area Network)
It is also called LAN and designed for small physical areas such as an office, group of buildings or a
factory. LANs are used widely as it is easy to design and to troubleshoot. Personal computers and
workstations are connected to each other through LANs. We can use different types of topologies
through LAN, these are Star, Ring, Bus, Tree etc.
MAN(Metropolitan Area Network)
It is basically a bigger version of LAN. It is also called MAN and uses the similar technology as LAN.
It is designed to extend over the entire city. It can be means to connecting a number of LANs into a
larger network or it can be a single cable. It is mainly hold and operated by single private company
or a public company.

13. WAN(Wide Area Network)
It is also called WAN. WAN can be private or it can be public leased network. It is used for the
network that covers large distance such as cover states of a country. It is not easy to design and
maintain. Communication medium used by WAN are PSTN or Satellite links. WAN operates on low
data rates.
Hub
A hub is a physical layer networking device which is used to connect multiple devices in a network.
They are generally used to connect computers in a LAN. A hub has many ports in it. A computer
which intends to be connected to the network is plugged in to one of these ports.

14. Modem
A modem is a device that modulates an analog carrier signal to encode digital information and also
demodulates such a carrier signal to decode the transmitted information. The goal is to produce a
signal that can be transmitted easily and decoded to reproduce the original digital data. Modems
can be used over any means of transmitting analog signals, from light emitting diodes to radio.
Switch
Switched communication networks are those in which data transferred from source to destination
is routed between various intermediate nodes. Switching is the technique by which nodes control
or switch data to transmit it between specific points on a network.

15. Router
A router is a networking device that forwards data packets between computer networks.
It connects different networks together and sends data packets from one network to another. A
router can be used both in LANs (Local Area Networks) and WANs (Wide Area Networks). It
transfers data in the form of IP packets.

16. Network addressing
A network address is an identifier for a node or host on a telecommunications network. Network
addresses are designed to be unique identifiers across the network, although some networks allow
for local, private addresses, or locally administered addresses that may not be unique.
physical addressing
In computing, a physical address (also real address, or binary address), is a memory address that is
represented in the form of a binary number on the address bus circuitry.
The MAC address is a physical address (also called a hardware address) because it physically
identifies an item of hardware.
Logical addressing
In computing, a logical address is the address at which an item (memory cell, storage element,
network host) appears to reside from the perspective of an executing application program. A logical
address may be different from the physical address due to the operation of an address translator
or mapping function.
For example, in a typical IP address, such as 192.168. 1.102, the network address is 192.168.
IP
The Internet Protocol (IP) is a protocol, or set of rules, for routing and addressing packets of data
so that they can travel across networks and arrive at the correct destination. Data traversing the
Internet is divided into smaller pieces, called packets

17. IP classes
Currently there are five classes of TCP/IP networks. Each class uses the 32-bit IP address space
differently, providing more or fewer bits for the network part of the address. These classes are :
 class A (01-126)
 class B (128-191)
 class C(192-223)
 class D(224-239)
 class E(240-255)
Local Loopback Address is used to let a systemsend a message to itself to make sure that TCP/IP
stack is installed correctly on the machine. In IPv4, IP addresses that start with decimal 127 or
that has 01111111 in the first octet are loopback addresses(127. X.X.X). Typically 1127.0.
Digital modulation
Modulation is the process of converting data into radio waves by adding information to an
electronic or optical carrier signal.
The simplest modulation, a type of unipolar encoding, is simply to switch on and off a DC signal
so that high voltages represent a '1' and low voltages are '0'.
Digital modulation
ASK FSK PSK
ASK(Amplitude shift keying)
ASK refers to a type of amplitude modulation that assigns bit values to discrete amplitude levels.
It transfer signal using fiber optic cable .
FSK
FSK refers to a type of frequency modulation that assigns bit values to discrete frequency levels.
It transfer signal using coaxial cable.

18. High frequency - 1
Low frequency – 0
Phase-shift keying (PSK)
Phase-shift keying (PSK) is a digital modulation process which conveys data by changing
(modulating) the phase of a constant frequency reference signal (the carrier wave).
It transfer signal using.
Reference- Wikipedia
Base band
Baseband Transmission is a signaling technology that sends digital signals over a singlefrequency
as discrete electrical pulses.
Baseband technology uses digital signal in data transmission.It sends binary values directly as
pulses of different voltage levels.
Broad band
Broadband refers to various high-capacity transmission technologies that are used to transmit
data, voice, and video across long distances and at high speeds.
Broadband is typically used in an environment that transmits audio, video, and data
simultaneously. For example, Cable TV Networks, Radio stations, and Telephone companies.
Reference
https://networkencyclopedia.com/baseband-transmission/
https://www.investopedia.com/terms/b/broadband.asp
(Reference – data communication 1st class.pdf )
https://www.differencebetween.com/difference-between-encapsulation-and-vs-
decapsulation/
https://youtube.com/channel/UCcWjp69-8Lb2IPZoyro80Ag
Reference- class note from computer networks