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IP Addresses: Classful Addressing LECTURE -3 IP ADDRESSES 1

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Page 1: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

IP Addresses:

Classful Addressing

LECTURE -3 IP ADDRESSES

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Page 2: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

CONTENTS

• INTRODUCTION

• CLASSFUL ADDRESSING

• Different Network Classes

• Subnetting

• Classless Addressing

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Page 3: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

INTRODUCTION

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Page 4: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

WHAT IS AN IP ADDRESS

A way to identify machines on a network

A unique identifier

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Page 5: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

IP USAGE

Used to connect to another computer

Allows transfers of files and e-mail

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Page 6: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

IP STRUCTURE

IP addresses consist of four sections

Each section is 8 bits long

Each section can range from 0 to 255

Written, for example, 128.35.0.72

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Page 7: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

IP STRUCTURE

These four sections represent the machine itself

and the network it is on

The network portion is assigned.

The host section is determined by the network

administrator

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Page 8: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

IP STRUCTURE

5 Classes of IP address A B C D and E

Class A reserved for governments

Class B reserved for medium companies

Class C reserved for small companies

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Page 9: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

IP STRUCTURE

Class D are reserved for multicasting

Class E are reserved for future use

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Page 10: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

IP STRUCTURE

Class A begins 1 to 126

Class B begins 128 to

191

Class C begins 192 to

223

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Page 11: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

An IP address is a

32-bit

address.

What is an IP Address?

The IP addresses

are

unique. 11

Page 12: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Address Space

addr15addr1

addr2

addr41addr31

addr226

…………..…………..

…………..…………..

…………..

…………..…………..

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Page 13: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Address space rule

addr15addr1

addr2

addr41addr31

addr226

…………..…………..

…………..…………..

…………..

…………..…………..

The address space in a protocol

That uses N-bits to define an

Address is:

2N

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Page 14: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

The address space of IPv4 is

232

or

4,294,967,296.

IPv4 address space

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Page 15: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

01110101 10010101 00011101 11101010

Binary Notation

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Page 16: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Dotted-decimal notation

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Page 17: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

0111 0101 1001 0101 0001 1101 1110 1010

Hexadecimal Notation

75 95 1D EA

0x75951DEA

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Page 18: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Example 1

Change the following IP address from

binary notation to dotted-decimal

notation.

10000001 00001011 00001011

11101111Solution

129.11.11.23918

Page 19: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Example 2

Change the following IP address

from dotted-decimal notation to

binary notation:

111.56.45.78

Solution

01101111 00111000 00101101 0100111019

Page 20: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Example 3

Solution

Find the error in the following IP Address

111.56.045.78

There are no leading zeroes in

Dotted-decimal notation (045) 20

Page 21: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Example 3 (continued)

Solution

Find the error in the following IP Address

75.45.301.14

In decimal notation each number <= 255

301 is out of the range21

Page 22: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Example 4

Solution

Change the following binary IP address

Hexadecimal notation

10000001 00001011 00001011 11101111

0X810B0BEF or 810B0BEF16 22

Page 23: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

RESERVED ADDRESSES

Addresses beginning 127 are reserved for

loopback and internal testing

xxx.0.0.0 reserved for network address

xxx.255.255.255 reserved for broadcast

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Page 24: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

IP ADDRESSES

IP addresses are:

Unique

Global and Standardised

Essential

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Page 25: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

SUBNETTING - WHY?

Division of local networks

Greater number of networks

Simplifies addressing

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Page 26: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

SUBNETTING - HOW

Bits borrowed from host field

Network Network Host Host

Network Network Subnet Host

Network Network Subnet Subnet/Host

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Page 27: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

SUBNETTING -EXAMPLE

130.5.0.0 - Network address

130.5.2.144 - Host address

255.255.255.0 - Subnet Mask

130.5.2.0 - Subnet

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Page 28: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Occupation of the address space

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Page 29: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

In classful addressing the address space is

divided into 5 classes:

A, B, C, D, and E.

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Page 30: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Finding the class in binary notation

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Page 31: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Finding the address class

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Page 32: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Show that Class A has

231 = 2,147,483,648 addresses

Example 5

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Page 33: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Example 6

Solution

Find the class of the following IP addresses

00000001 00001011 00001011 11101111

11000001 00001011 00001011 11101111

•00000001 00001011 00001011 11101111

1st is 0, hence it is Class A

•11000001 00001011 00001011 111011111st and 2nd bits are 1, and 3rd bit is 0 hence, Class C

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Page 34: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Finding the class in decimal notation

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Page 35: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Example 7

Solution

Find the class of the following addresses

158.223.1.108

227.13.14.88

•158.223.1.108

1st byte = 158 (128<158<191) class B

•227.13.14.88

1st byte = 227 (224<227<239) class D 35

Page 36: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

IP ADDRESS WITH APPENDING PORT

NUMBER

158.128.1.108:25

the for octet before colon is the IP address

The number of colon (25) is the port number

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Page 37: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Netid and hostid

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Page 38: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Blocks in class A

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Page 39: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Millions of class A addresses

are wasted.

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Page 40: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Blocks in class B

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Page 41: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Many class B addresses

are wasted.

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Page 42: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Blocks in class C

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Page 43: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

The number of addresses in

a class C block

is smaller than

the needs of most organizations.

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Page 44: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Class D addresses

are used for multicasting;

there is only

one block in this class.

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Page 45: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Class E addresses are reserved

for special purposes;

most of the block is wasted.

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Page 46: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Network

Addresses

The network address is the first address.

The network address defines the network

to the rest of the Internet.

Given the network address, we can find the

class of the address, the block, and the

range of the addresses in the block 46

Page 47: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

In classful addressing,

the network address

(the first address in the block)

is the one that is assigned

to the organization.

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Page 48: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Example 8

Solution

Given the network address 132.21.0.0, find the

class, the block, and the range of the addresses

The 1st byte is between 128 and 191.

Hence, Class B

The block has a netid of 132.21.

The addresses range from

132.21.0.0 to 132.21.255.255.48

Page 49: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

Mask

• A mask is a 32-bit binary number.

• The mask is ANDeD with IP address to get

• The bloc address (Network address)

• Mask And IP address = Block Address

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Page 50: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

The network address is the

beginning address of each block.

It can be found by applying

the default mask to

any of the addresses in the block

(including itself).

It retains the netid of the block

and sets the hostid to zero. 50

Page 51: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

DEFAULT MAK

Class A default mask is 255.0.0.0

Class B default mask is 255.255.0.0

Class C Default mask 255.255.255.0

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SUBNETTING

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Page 53: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

IP addresses are designed with

two levels of hierarchy.

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Page 54: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

A network with two levels of

hierarchy (not subnetted)

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Page 55: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

A network with three levels of

hierarchy (subnetted)

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Page 56: IP Addresses: Classful Addressing · •CLASSFUL ADDRESSING •Different Network Classes •Subnetting •Classless Addressing 2. INTRODUCTION 3. WHAT IS AN IP ADDRESS A way to identify

THE INTERNET PROTOCOL

Running out!!

Upgraded to IPv6

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QUESTIONS/COMMENTS?

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