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
