The document discusses the Internet Protocol and the TCP/IP model. It defines what a protocol is and explains that protocols establish rules for data communication between devices. It then describes the five layers of the TCP/IP model: physical, data link, network, transport, and application. Each layer is responsible for different aspects of transmitting data packets from their source to destination. The document provides examples of the duties of each layer, such as framing data at the data link layer and logical addressing at the network layer.

1. COMPUTER APPLICATIONS
CLASS X (Code 165)
TOPIC:
UNIT 1: Internet Protocol
By
HIMANSHU PATHAK

2. Contents
• Introduction to Protocol
• TCP/IP model
• Basics of TCP/IP layers
– Physical Layer
– Data-link Layer
– Network Layer
– Transport Layer
– Application layer

3. Introduction
• Internet is a global communication system
that links together thousands of individual
networks.
• It allows exchange of information between
two or more computers on a network.
• Thus internet helps in transfer of messages
through mail, chat, video & audio conference,
etc.

4. Protocol
• A Protocol is a set of rules that governs data
communication.
• A Protocol defines what is communicated?, how
it is communicated?, and when it is
communicated?
• Multiple protocols work together to ensure that
data is communicated between devices in a
network.
– Examples include HTTP for browsing, FTP for file
transfer, SMTP for email etc.

5. Cont…
• The key elements of protocols are:
– Syntax: Syntax refers to the structure or format of
data(the order in which they are presented).
– Semantics: Semantics refers to the meaning of each
section of bits.
– Timing : When data should be sent and how fast they
can sent.
– size of the message
– error checking

6. Cont…
• Protocols establish how two computers send and receive a
message.
• Data packets travel between source and destination from
one router to the next.
• The process of exchanging data packets is known as
packet switching.
• When two devices send messages to each other it is called
handshaking -
– the client requests access,
– the server grants it, and
– the protocols are agreed.
• Once the handshaking process is complete, the data
transfer can begin.

7. Internet Model or TCP/IP model
• TCP/IP (also known as the internet protocol suite) is
the set of protocols used over the internet.
• It organizes how data packets are communicated
and makes sure packets have the following
information:
– source - which computer the message came from
– destination - where the message should go
– packet sequence - the order in which the message data
should be re-assembled
– data - the data of the message
– error check - the check to see that the message has been
sent correctly.

8. TCP/IP Model Layers
• The model is composed of 5 ordered Layers:
– Physical Layer
– Data Link Layer
– Network Layer
– Transport Layer
– Application Layer

9. Physical Layer
• The Physical layer is responsible for transmitting
individual bits from one node to the next.
• The physical layer defines the type of
Transmission medium (Cable Media).
• The transmission rate i.e. bandwidth (the
number of bits sent each second) is also defined
by the physical layer.
• It also describes the topology (physical
arrangement of the system/network)

10. Data Link Layer
• Data link layer is responsible for the transmitting frames
from one node to the next.
• The Major duty of data link layer are:
– Framing: it divides the stream of bits received from network
layer into manageable data units called Frames.
– Physical Addressing: it adds a header to the frame to define
the sender / receiver of the frame (MAC Address).
– Flow control: Sequentially transmitting and receiving frames.
– Error Control: Detect and retransmit damaged or lost frames.
– Access Control: when two or more devices are connected to
the same link, data link layer protocol determines which device
has control over the link.

11. Network Layer
• The network layer is responsible for the delivery
of packets from the original source to the final
destination.
• The major duties are:
– Logical Addressing
– Routing
• Note:- If source and destination are in the same
network/same link then there is usually no need
for a network layer.

12. Transport Layer
• The transport layer is responsible for process to
process delivery of the entire message.
• The major duties of transport layer are:
– Port Addressing
– Segmentation and reassembly
– Connection Control (connectionless-UDP or
Connection-oriented-TCP)
– Flow control
– Error control

13. Application Layer
• The Application layer is responsible for providing
services to the end user.
• Following are the services provided by the
application layer:
– Mail Service
– File transfer and Access
– Remote login
– Accessing the WWW

14. Today we learn
• Introduction to protocol
• Basics of TCP/IP Layers.
• In the next class, we will see Various protocols
used in Application Layer in detail.
•Thanks