ip addresses: classful addressing · •classful addressing •different network classes...
TRANSCRIPT
IP Addresses:
Classful Addressing
LECTURE -3 IP ADDRESSES
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CONTENTS
• INTRODUCTION
• CLASSFUL ADDRESSING
• Different Network Classes
• Subnetting
• Classless Addressing
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INTRODUCTION
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WHAT IS AN IP ADDRESS
A way to identify machines on a network
A unique identifier
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IP USAGE
Used to connect to another computer
Allows transfers of files and e-mail
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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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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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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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IP STRUCTURE
Class D are reserved for multicasting
Class E are reserved for future use
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IP STRUCTURE
Class A begins 1 to 126
Class B begins 128 to
191
Class C begins 192 to
223
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An IP address is a
32-bit
address.
What is an IP Address?
The IP addresses
are
unique. 11
Address Space
addr15addr1
addr2
addr41addr31
addr226
…………..…………..
…………..…………..
…………..
…………..…………..
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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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The address space of IPv4 is
232
or
4,294,967,296.
IPv4 address space
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01110101 10010101 00011101 11101010
Binary Notation
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Dotted-decimal notation
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0111 0101 1001 0101 0001 1101 1110 1010
Hexadecimal Notation
75 95 1D EA
0x75951DEA
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Example 1
Change the following IP address from
binary notation to dotted-decimal
notation.
10000001 00001011 00001011
11101111Solution
129.11.11.23918
Example 2
Change the following IP address
from dotted-decimal notation to
binary notation:
111.56.45.78
Solution
01101111 00111000 00101101 0100111019
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
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
Example 4
Solution
Change the following binary IP address
Hexadecimal notation
10000001 00001011 00001011 11101111
0X810B0BEF or 810B0BEF16 22
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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IP ADDRESSES
IP addresses are:
Unique
Global and Standardised
Essential
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SUBNETTING - WHY?
Division of local networks
Greater number of networks
Simplifies addressing
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SUBNETTING - HOW
Bits borrowed from host field
Network Network Host Host
Network Network Subnet Host
Network Network Subnet Subnet/Host
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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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Occupation of the address space
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In classful addressing the address space is
divided into 5 classes:
A, B, C, D, and E.
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Finding the class in binary notation
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Finding the address class
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Show that Class A has
231 = 2,147,483,648 addresses
Example 5
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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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Finding the class in decimal notation
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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
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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Netid and hostid
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Blocks in class A
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Millions of class A addresses
are wasted.
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Blocks in class B
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Many class B addresses
are wasted.
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Blocks in class C
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The number of addresses in
a class C block
is smaller than
the needs of most organizations.
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Class D addresses
are used for multicasting;
there is only
one block in this class.
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Class E addresses are reserved
for special purposes;
most of the block is wasted.
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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
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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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
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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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
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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IP addresses are designed with
two levels of hierarchy.
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A network with two levels of
hierarchy (not subnetted)
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A network with three levels of
hierarchy (subnetted)
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THE INTERNET PROTOCOL
Running out!!
Upgraded to IPv6
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QUESTIONS/COMMENTS?
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