Because learning changes everything.

®
Collected by:
Dr. Pinaki Sankar Chatterjee

Chapter 01

Introduction
Data Communications and
Networking, With TCP/IP
protocol suite
Sixth Edition
Behrouz A. Forouzan

© 2022 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom.
No reproduction or further distribution permitted without the prior written consent of McGraw Hill, LLC.
 Chapter 3: Outline

1.1 DATA COMMUNICATIONS

1.2 NETWORKS

1.3 NETWORK TYPES

1.4 PROTOCOL LAYERING

1.5 TCP/IP PROTOCOL SUITE

1.6 THE OSI MODEL

© McGraw Hill, LLC 2

 1.1 DATA COMMUNICATIONS

Data communication is the exchange of data between two devices

via some form of transmission media. It depends on four
characteristics:
1. Delivery
2. Accuracy
3. Timeliness
4. Jitter

© McGraw Hill, LLC 3

 1.1.1 Components

A data communications system has five components:

1. Message
2. Sender
3. Receiver
4. Transmission Medium
5. Protocol
(Figure 1.1)

© McGraw Hill, LLC 4

 Figure 1.1 Five components of data communication

Access the text alternative for slide images.

© McGraw Hill, LLC 5

 1.1.2 Message

Information today comes in different forms such as text, numbers,

images, audio, and video.

© McGraw Hill, LLC 6

 Text

Text is represented as a bit pattern using Unicode.

© McGraw Hill, LLC 7

 Numbers

Numbers are represented in binary.

© McGraw Hill, LLC 8

 Images

Images are represented as bit patterns using either RGB or YCM.

© McGraw Hill, LLC 9

 Audio

Audio refers to the recording or broadcasting of sound or music,

represented as analog or digital signals.

© McGraw Hill, LLC 10

 Video

Videos can be a continues images or a combination of images.

© McGraw Hill, LLC 11

 1.1.3 Data Flow

Communication between two devices can be simplex, half-duplex,

and duplex as shown in Figure 1.2.

© McGraw Hill, LLC 12

 Figure 1.2 Data flow (simplex, half-duplex, full-duplex)

Access the text alternative for slide images.

© McGraw Hill, LLC 13

 Simplex

In simplex mode the communication is in one direction. Only one of

the two connected devices can send or receive.

© McGraw Hill, LLC 14

 Half-Duplex

In half-duplex, each station can send or receive, but not at the same
time.

© McGraw Hill, LLC 15

 Full-Duplex

In full-duplex, both stations can send or receive at the same time.

© McGraw Hill, LLC 16

 1-2 NETWORKS

A network is the interconnection of a set of devices capable of

communication. In this definition, a device can be a host such as a
large computer, desktop, laptop, workstation, cellular phone, or
security system. A device in this definition can also be a connecting
device such as a router a switch, a modem that changes the form of
data, and so on.

© McGraw Hill, LLC 17

 1.2.1 Network Criteria

A network must be able to meet a certain number of criteria. The

most important of these are: performance, reliability, and security.

© McGraw Hill, LLC 18

 Performance

Performance can be measured in many ways, including transit time

and response time. Transit time is the amount of time required for a
message to travel from one device to another. Response time is the
elapsed time between an inquiry and a response.

© McGraw Hill, LLC 19

 Reliability

In addition to accuracy of delivery, network reliability is measured

by the frequency of failure, the time it takes a link to recover from a
failure, and the network’s robustness in a catastrophe.

© McGraw Hill, LLC 20

 Security

Network security issues include protecting data from unauthorized

access, protecting data from damage and development, and
implementing policies and procedures for recovery from breaches
and data losses.

© McGraw Hill, LLC 21

 1.2.2 Physical Structures

Before discussing networks, we need to define some network

structures.

© McGraw Hill, LLC 22

 Types of Connection

A network is two or more devices connected through links. A link is

a communications pathway that transfers data from one device to
another. There are two possible types of connections: point-to-point
and multipoint (see Figure 1.3)

© McGraw Hill, LLC 23

 Figure 1.3 Types of connection

Access the text alternative for slide images.

© McGraw Hill, LLC 24

 Physical Topology

The term physical topology refers to the way in which a network is

laid out physically. Two or more devices connect to a link; two or
more links form a topology. The topology of a network is the
geometric representation of the relationship of all the links and
linking devices (usually called nodes) to one another. There are
four basic topologies possible: mesh, star, bus, and ring.

© McGraw Hill, LLC 25

 Figure 1.4 A fully connected mesh topology

n=5 10 links

Access the text alternative for slide images.

© McGraw Hill, LLC 26

 Figure 1.5 A star topology

© McGraw Hill, LLC 27

 Figure 1.6 A bus topology

Access the text alternative for slide images.

© McGraw Hill, LLC 28

 Figure 1.7 A ring topology

Access the text alternative for slide images.

© McGraw Hill, LLC 29

 1-3 NETWORK TYPES

A network can be of two types: LANs and WANs

© McGraw Hill, LLC 30

 1.3.1 Local Area Network (LAN)

A local area network (LAN) is usually privately owned and

connects some hosts in a single office, building, or campus.

© McGraw Hill, LLC 31

 Figure 1.8 An isolated LAN in the past and today

Access the text alternative for slide images.

© McGraw Hill, LLC 32

 1.3.2 Wide Area Network (WAN)

A wide area network (WAN) is also a connection of devices capable

of communication. a WAN has a wider geographical span,
spanning a town, a state, a country, or even the world.

© McGraw Hill, LLC 33

 Point-to-Point WAN

A point-to-point WAN is a network that connects two

communicating devices through a transmission media (cable or
air). Figure 1.9 shows an example of a point-to-point WAN.

© McGraw Hill, LLC 34

 Figure 1.9 A point-to-point WAN

Access the text alternative for slide images.

© McGraw Hill, LLC 35

 Switched WAN

A switched WAN is a network with more than two ends. A switched

WAN is used in the backbone of global communication today.
Figure 1.10 shows an example of a switched WAN.

© McGraw Hill, LLC 36

 Figure 1.10 A switched WAN

Access the text alternative for slide images.

© McGraw Hill, LLC 37

 Internetwork

Today, it is very rare to see a LAN or a WAN in isolation; they are

connected to one another. When two or more networks are
connected, they make an internetwork, or internet.

© McGraw Hill, LLC 38

 Figure 1.11 An internetwork made of two LANs and one WAN

Access the text alternative for slide images.

© McGraw Hill, LLC 39

 Figure 1.12 A heterogeneous network made of WANs and LANs

Access the text alternative for slide images.

© McGraw Hill, LLC 40

 1.3.3 The Internet

An internet (note the lowercase i) is two or more networks that can

communicate with each other. The most notable internet is called
the Internet (uppercase I) and is composed of millions of
interconnected networks. Figure 1.13 shows a conceptual (not
geographical) view of the Internet.

© McGraw Hill, LLC 41

 Figure 1.13 The Internet today

Access the text alternative for slide images.

© McGraw Hill, LLC 42

 1.3.4 Accessing the Internet

The Internet today is an internetwork that allows any user to

become part of it. The user, however, needs to be physically
connected to an ISP. The physical connection is normally done
through a point-to-point WAN.

© McGraw Hill, LLC 43

 Using Telephone Networks

Today most residences and small businesses have telephone

service, which means they are connected to a telephone network.
Since most telephone networks have already connected themselves
to the Internet, one option for residences and small businesses to
connect to the Internet is to change the voice line between the
residence or business and the telephone center to a point-to-point
WAN.

© McGraw Hill, LLC 44

 Using Cable Networks

More and more residents over the last two decades have begun
using cable TV services instead of antennas to receive TV
broadcasting. The cable companies have been upgrading their
cable networks and connecting to the Internet. A residence or a
small business can be connected to the Internet by using this
service.

© McGraw Hill, LLC 45

 Using Wireless Networks

Wireless connectivity has recently become increasingly popular. A

household or a small business can use a combination of wireless
and wired connections to access the Internet. With the growing
wireless WAN access, a household or a small business can be
connected to the Internet through a wireless WAN.

© McGraw Hill, LLC 46

 Direct Connection to the Internet

A large organization or a large corporation can itself become a

local ISP and be connected to the Internet. This can be done if the
organization or the corporation leases a high-speed WAN from a
carrier provider and connects itself to a regional ISP. For example,
a large university with several campuses can create an
internetwork and then connect the internetwork to the Internet.

© McGraw Hill, LLC 47

 1-4 PROTOCOL LAYERING

We defined the term protocol before. In data communication and

networking, a protocol defines the rules that both the sender and
receiver and all intermediate devices need to follow to be able to
communicate directly.

© McGraw Hill, LLC 48

 1.4.1 Scenarios

Let us develop two simple scenarios to better understand the need

for protocol layering.

© McGraw Hill, LLC 49

 First Scenario

A large organization or a large corporation can itself become a

local ISP and be connected to the Internet. This can be done if the
organization or the corporation leases a high-speed WAN from a
carrier provider and connects itself to a regional ISP.

© McGraw Hill, LLC 50

 Figure 1.14 A single-layer protocol

Access the text alternative for slide images.

© McGraw Hill, LLC 51

 Second Scenario

In the second scenario, we assume that Ann is offered a

higher-level position in her company, but needs to move to another
branch located in a city very far from Maria. They decide to
continue their conversion using regular mail through the post
office. However, they do not want their ideas to be revealed by
other people if the letters are intercepted. They use an
encryption/decryption technique.

© McGraw Hill, LLC 52

 Figure 1.15 A three-layer protocol

Access the text alternative for slide images.

© McGraw Hill, LLC 53

 1.4.2 Principles of Protocol Layering

Let us discuss two principles of protocol layering.

© McGraw Hill, LLC 54

 First Principle

The first principle dictates that we need to make each layer to

perform two opposite task in each direction.

© McGraw Hill, LLC 55

 Second Principle

The second principle dictates that two objects under each layer
should be identical.

© McGraw Hill, LLC 56

 1.4.3 Logical Connections

After following the above two principles, we can think about

logical connection between each layer as shown in Figure 1.16.

© McGraw Hill, LLC 57

 Figure 1.16 Logical connection between peer layers

Access the text alternative for slide images.

© McGraw Hill, LLC 58

 1-5 TCP/IP PROTOCOL SUITE

Now we can introduce the TCP/IP (Transmission Control Protocol /

Internet Protocol). This is the protocol suite used in the Internet
today.

© McGraw Hill, LLC 59

 Figure 1.17 Layers in the TCP/IP protocol suite

Access the text alternative for slide images.

© McGraw Hill, LLC 60

 1.5.1 Layered Architecture

To show how the layers in the TCP/IP protocol suite are involved in
communication between two hosts, we assume that we want to use
the suite in a small internet made up of three LANs (links), each
with a link-layer switch. We also assume that the links are
connected by one router, as shown in Figure 1.18.

© McGraw Hill, LLC 61

 Figure 1.18 Communication through an internet

Access the text alternative for slide images.

© McGraw Hill, LLC 62

 1.5.2 Brief Description of Layers

After the above introduction, we briefly discuss the functions and

duties of layers in the TCP/IP protocol suite. Each layer is
discussed in detail in the next five parts of the book. To better
understand the duties of each layer, we need to think about the
logical connections between layers. Figure 1.19 shows logical
connections in our simple internet.

© McGraw Hill, LLC 63

 Figure 1.19 Logical connections between layers in TCP/IP

Access the text alternative for slide images.

© McGraw Hill, LLC 64

 Figure 1.20 Identical objects in the TCP/IP protocol suite

Access the text alternative for slide images.

© McGraw Hill, LLC 65

 1.5.3 Description of Each Layer

After understanding the concept of logical communication, we are

ready to briefly discuss the duty of each layer. Our discussion in
this chapter will be very brief, but we come back to the duty of each
layer in next five parts of the book.

© McGraw Hill, LLC 66

 Physical Layer

We can say that the physical layer is responsible for carrying

individual bits in a frame across the link. The physical layer is the
lowest level in the TCP/IP protocol suite, the communication
between two devices at the physical layer is still a logical
communication because there is another, hidden layer, the
transmission media, under the physical layer. We discuss Physical
Layer in Chapter 2.

© McGraw Hill, LLC 67

 Data Link Layer

We have seen that an internet is made up of several links (LANs

and WANs) connected by routers. When the next link to travel is
determined by the router, the data-link layer is responsible for
taking the datagram and moving it across the link. We discuss
Data-Link Layer in Chapter 3.

© McGraw Hill, LLC 68

 Network Layer

The network layer is responsible for creating a connection between

the source computer and the destination computer. The
communication at the network layer is host-to-host. However, since
there can be several routers from the source to the destination, the
routers in the path are responsible for choosing the best route for
each packet. We discuss Network Layer in Chapter 4.

© McGraw Hill, LLC 69

 Transport Layer

The logical connection at the transport layer is also end-to-end.

The transport layer at the source host gets the message from the
application layer, encapsulates it in a transport-layer packet. In
other words, the transport layer is responsible for giving services to
the application layer: to get a message from an application
program running on the source host and deliver it to the
corresponding application program on the destination host.
transmits user datagrams without first creating a logical
connection. We discuss Transport Layer in Chapter 9.

© McGraw Hill, LLC 70

 Application Layer

The logical connection between the two application layers is

end-to-end. The two application layers exchange messages between
each other as though there were a bridge between the two layers.
However, we should know that the communication is done through
all the layers. Communication at the application layer is between
two processes (two programs running at this layer). To
communicate, a process sends a request to the other process and
receives a response. Process-to-process communication is the duty
of the application layer. We discuss Application Layer in Chapter
10.

© McGraw Hill, LLC 71

 1-6 OSI MODEL

Although, when speaking of the Internet, everyone talks about the

TCP/IP protocol suite, this suite is not the only suite of protocols
defined. Established in 1947, the International Organization for
Standardization (ISO) is a multinational body dedicated to
worldwide agreement on international standards. Almost
three-fourths of the countries in the world are represented in the
ISO. An ISO standard that covers all aspects of network
communications is the Open Systems Interconnection (OSI) model.
It was first introduced in the late 1970s.

© McGraw Hill, LLC 72

 Figure 1.21 The OSI model

Access the text alternative for slide images.

© McGraw Hill, LLC 73

 1.6.1 OSI versus TCP/IP

When we compare the two models, we find that two layers, session
and presentation, are missing from the TCP/IP protocol suite.
These two layers were not added to the TCP/IP protocol suite after
the publication of the OSI model. The application layer in the suite
is usually considered to be the combination of three layers in the
OSI model, as shown in Figure 1.22.

© McGraw Hill, LLC 74

 Figure 1.22 TCP/IP and OSI model

Access the text alternative for slide images.

© McGraw Hill, LLC 75

 1.6.2 Lack of OSI Model’s Success

The OSI model appeared after the TCP/IP protocol suite. Most
experts were at first excited and thought that the TCP/IP protocol
would be fully replaced by the OSI model. This did not happen for
several reasons, but we describe only three, which are agreed upon
by all experts in the field.

© McGraw Hill, LLC 76

Because learning changes everything. ®

www.mheducation.com

© 2022 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom.
No reproduction or further distribution permitted without the prior written consent of McGraw Hill, LLC.
 Accessibility Content: Text Alternatives for Images

© McGraw Hill, LLC 78

 Figure 1.1 Five components of data communication - Text
Alternative
Return to parent-slide containing images.

The communication system includes five major components: sender, receiver,

message to be communicated, medium of the communication, and protocol for
both sender and receiver. The protocols of both sender and receiver consists of 'n'
number of rules.

Return to parent-slide containing images.

© McGraw Hill, LLC 79

 Figure 1.2 Data flow (simplex, half-duplex, full-duplex) - Text
Alternative
Return to parent-slide containing images.

The simplex, half-duplex, and full-duplex modes of data flow are demonstrated.
The simplex mode (a) represents the transformation of data from a mainframe to
a monitor in one direction. The half-duplex mode (b) represents the
transformation of data from one laptop to another laptop in two-way directions in
which the data is send from the first laptop to the second laptop at time 1 and the
data is send from the second laptop to the first laptop at time 2. The full-duplex
mode (c) represents the transformation of data between two laptops in two-way
directions all the time.

Return to parent-slide containing images.

© McGraw Hill, LLC 80

 Figure 1.3 Types of connection - Text Alternative
Return to parent-slide containing images.

The point-to-point connections represents the direct link between two laptops.
The multipoint connection represents a common link from a mainframe that is
shared by three other laptops.

Return to parent-slide containing images.

© McGraw Hill, LLC 81

 Figure 1.4 A fully connected mesh topology - Text Alternative
Return to parent-slide containing images.

A schematic representation of a mesh topology shows five laptops connected in a

pentagonal shape. Each laptop is connected to all the other four laptops.

Return to parent-slide containing images.

© McGraw Hill, LLC 82

 Figure 1.6 A bus topology - Text Alternative
Return to parent-slide containing images.

A linear cable with three taps, arranged in series is shown. The cable has a cable
end on both sides. A laptop is connected to each tap with a drop line.

Return to parent-slide containing images.

© McGraw Hill, LLC 83

 Figure 1.7 A ring topology - Text Alternative
Return to parent-slide containing images.

A cyclic network with six repeaters is shown. A laptop is connected to each

repeater.

Return to parent-slide containing images.

© McGraw Hill, LLC 84

 Figure 1.8 An isolated LAN in the past and today - Text
Alternative
Return to parent-slide containing images.

Two L A N topologies are shown. The first one is a LAN with a common cable
(past). It shows eight host devices labeled as host 1, host 2, host 3, host 4, host 5,
host 6, host 7, and host 8, connected to eight taps on a common cable that has
cable ends on both sides. The second one is a L A N with a switch (today). It
shows each host devices labeled as host 1, host 2, host 3, host 4, host 5, host 6,
host 7, and host 8, connected to a switch through eight different connections. A
legend below lists the components and their names used in the topology. They
are as follows: a host (of any type), switch, cable tap, cable end, common cable,
and connection.

Return to parent-slide containing images.

© McGraw Hill, LLC 85

 Figure 1.9 A point-to-point WAN - Text Alternative
Return to parent-slide containing images.

A connecting device is connected to another connecting device through a

connecting medium. The connecting medium extends to another network at both
ends. A legend lists the components and their names: a connecting device and
connecting medium.

Return to parent-slide containing images.

© McGraw Hill, LLC 86

 Figure 1.10 A switched WAN - Text Alternative
Return to parent-slide containing images.

A network topology with four switches, two on the top and top on the bottom is
shown. All the four switches are connected via connecting medium. The network
resembles a rectangle with switches on the four corners. Two connections are
established on the free ends of the four switches and these connections lead to
another network. A legend lists the components and their names: switch and
connecting medium.

Return to parent-slide containing images.

© McGraw Hill, LLC 87

 Figure 1.11 An internetwork made of two LANs and one WAN -
Text Alternative
Return to parent-slide containing images.

A network topology shows a local area network labeled as West coast office on
the left and another local area network labeled as East coast office on the right. In
each L A N, several host devices are connected to a switch through separate
connections. The switch on the West coast office L A N is connected to a router
labeled as R 1 and the switch on the East coast office L A N is connected to a
router labeled as R 2. The R 1 and R 2 are connected and this represents a
point-to-point wide area network.

Return to parent-slide containing images.

© McGraw Hill, LLC 88

 Figure 1.12 A heterogeneous network made of WANs and LANs -
Text Alternative
Return to parent-slide containing images.

A heterogenous internetwork topology is shown, where a local area network with

four host devices connected to a switch is connected to a point-to-point wide area
network that has two routers connected each other. Similarly, another local area
network with three host devices connected to a connecting device is connected to
a point-to-point wide area network that has two routers connected each other.
The routers from the two wide area networks are connected to the separate
connecting devices in a switched wide area network. The switched wide area
network has four switches connected in a diamond shape. One of the other two
switches in the switched wide area network connects to a modem. This modem is
connected to another modem, which in turn is connected to a resident host
device. The connection between the two modems represent a point-to-point wide
area network.

Return to parent-slide containing images.

© McGraw Hill, LLC 89

 Figure 1.13 The Internet today - Text Alternative
Return to parent-slide containing images.

A network topology representing the internet shows several backbones connected

to several provider networks and peering points. The peering points connect to
the provider networks. The provider networks connect to multiple customer
networks. The provider networks establish connections between them. Similarly,
the customer networks have connections between them.

Return to parent-slide containing images.

© McGraw Hill, LLC 90

 Figure 1.14 A single-layer protocol - Text Alternative
Return to parent-slide containing images.

In single layer protocol, the two persons named Maria on one side and Ann on
another side communicates (listen or talk) through air medium. The listen or talk
actions on both sides are represented as layer 1.

Return to parent-slide containing images.

© McGraw Hill, LLC 91

 Figure 1.15 A three-layer protocol - Text Alternative
Return to parent-slide containing images.

In three layer protocol, the communication between Maria and Ann is shown in
three layers. The layer 1 is sending mail or receiving mail. The layer 2 is
encrypting or decrypting the mail to a Ciphertext. The layer 3 is listening or
talking where the ciphertext is converted to a plaintext. Each peer layers share
identical objects that is the mail, ciphertext, and plaintext in both sides (Maria
and Ann) are identical objects.

Return to parent-slide containing images.

© McGraw Hill, LLC 92

 Figure 1.16 Logical connection between peer layers - Text
Alternative
Return to parent-slide containing images.

A three layer protocol communication between Maria and Ann is shown is

demonstrated. The layer 1 is sending mail or receiving mail. The layer 2 is
encrypting or decrypting the mail to a Ciphertext. The layer 3 is listening or
talking where the ciphertext is converted to a plaintext. Each peer layer
establishes a logical connection between the objects they share to the successive
layers

Return to parent-slide containing images.

© McGraw Hill, LLC 93

 Figure 1.17 Layers in the TCP/IP protocol suite - Text Alternative
Return to parent-slide containing images.

The five layers in the TCP or IP protocol are shown from bottom to top and are
as follows. Layer 1 - physical, layer 2 - data link, layer 3 - network, layer 4 -
transport, and layer 5 - application.

Return to parent-slide containing images.

© McGraw Hill, LLC 94

 Figure 1.18 Communication through an internet - Text
Alternative
Return to parent-slide containing images.

Two figures depict the communication through an internet. The first figure shows the data
flow between the source A and destination B via the different protocol layers. From the
application layer of source A, the data flows downward transport layer, network layer,
data link layer, and physical layer. From the physical layer, the data flows through the
physical and data link layer of a switch. From the data link layer of the switch, the data
again flows back to the physical layer. From which, the data flows through the physical,
data, and network layers of a router. From the network layer, the data flows through
another data link and physical layer of the router and reaches another switch. Here it flows
through the physical and data link layer and returns back in the same path and reaches the
physical layer of the TCP or IP protocol. Then the data flows upward through the data
link, network, transport, and reaches the application layer of destination B. The second
figure shows a network topology depicting the communication between two host devices
(A and B). A connects to a link 1 (a connecting device). Link 1 connects to a router. The
router connects to link 2. Link 2 connects to B. The router also connects to link 3, which
in turn connects to a host device (C).

Return to parent-slide containing images.

© McGraw Hill, LLC 95

 Figure 1.19 Logical connections between layers in TCP/IP - Text
Alternative
Return to parent-slide containing images.

The first part shows source host has physical, data link, network, transport, and
application. The destination has physical, data link, network, transport, and
application. The physical source host connects to a switch to the router to switch
to the physical destination host. The data link of the source host connects to
switch to the router to switch to the data link of the destination host. The network
of source hosts connects to the router to a network of the destination host. The
transport of the source host connects to the transport of the destination host. The
application of the source host connects to the application of the destination host.
The second part shows a laptop labeled as source host connects to link 1 of L A
N to the router to link 2 of L A N to a laptop labeled as destination host. The
router connects to link 3.

Return to parent-slide containing images.

© McGraw Hill, LLC 96

 Figure 1.20 Identical objects in the TCP/IP protocol suite - Text
Alternative
Return to parent-slide containing images.

An illustration shows that the first laptop and the second laptop have physical
data link, networks, transport, and application. Reversible communication
between the first and second laptops is shown. The application of first and
second laptops shares identical objects (messages). The transport of first and
second laptops shares identical objects (segments or user datagrams). The
network of first and second laptops shares identical objects (datagrams) through
the router. The data link of the first and second laptops shares identical objects
(frames) through the router. The physical of first and second laptops share
identical objects (bits) through the router. Notes: We have not shown switches
because they don’t change objects.

Return to parent-slide containing images.

© McGraw Hill, LLC 97

 Figure 1.21 The OSI model - Text Alternative
Return to parent-slide containing images.

The seven layers of the OSI model are shown from bottom to top and are as
follows. Layer 1 - physical, Layer 2 - data link, Layer 3 - network, Layer 4 -
transport, Layer 5 - session, Layer 6 - presentation, and Layer 7 - application.

Return to parent-slide containing images.

© McGraw Hill, LLC 98

 Figure 1.22 TCP/IP and OSI model - Text Alternative
Return to parent-slide containing images.

The O S I model has seven layers: physical, data link, network, transport,
session, presentation, and application layers (from bottom to top). The T C P/I P
protocol suite has five layers (from bottom to top): physical, data link, network,
transport, and application. The physical and data link layers represent underlying
L A N and W A N technology, the network layer represents internet protocol and
some helping protocols, transport layer represents several transport protocols,
and application layer represents several application protocols.

Return to parent-slide containing images.

© McGraw Hill, LLC 99