LECTURE -4 IP ADDRESSES IP Addresses: Classful Addressing 1
CONTENTS INTRODUCTION CLASSFUL ADDRESSING Different Network Classes Subnetting Classless Addressing 2
INTRODUCTION 3
WHAT IS AN IP ADDRESS A way to identify machines on a network A unique identifier 4
IP USAGE Used to connect to another computer Allows transfers of files and e-mail 5
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 6
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 7
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 8
IP STRUCTURE Class D are reserved for multicasting Class E are reserved for future use 9
IP STRUCTURE Class A begins 1 to 126 Class B begins 128 to 191 Class C begins 192 to 223 10
What is an IP Address? An IP address is a 32-bit address. The IP addresses are unique. 11
Address Space.. addr1.. addr15 addr2...... addr41 addr226 addr31.... 12
Address space rule.. addr1.. addr15 The addr2 address.. space in a protocol.. That.. uses N-bits to define an Address is: addr41 addr226 addr31.. 2 N.. 13
IPv4 address space The address space of IPv4 is 2 32 or 4,294,967,296. 14
Binary Notation 01110101 10010101 00011101 11101010 15
Dotted-decimal notation 16
Hexadecimal Notation 0111 0101 1001 0101 0001 1101 1110 101 75 95 1D EA 0x75951DEA 17
Example 1 Change the following IP address from binary notation to dotted-decimal notation. 10000001 00001011 00001011 Solution 11101111 129.11.11.239 18
Example 2 Change the following IP address from dotted-decimal notation to binary notation: Solution 111.56.45.78 19 01101111 00111000 00101101 0100111
Example 3 Find the error in the following IP Address 111.56.045.78 Solution There are no leading zeroes in Dotted-decimal notation (045) 20
Example 3 (continued) Find the error in the following IP Address 75.45.301.14 Solution In decimal notation each number <= 255 301 is out of the range 21
Example 4 Change the following binary IP address Hexadecimal notation 10000001 00001011 00001011 11101111 Solution 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 23
IP ADDRESSES IP addresses are: Unique Global and Standardised Essential 24
SUBNETTING - WHY? Division of local networks Greater number of networks Simplifies addressing 25
SUBNETTING - HOW Bits borrowed from host field Network Network Host Host Network Network Subnet Host Network Network Subnet Subnet/Host 26
SUBNETTING -EXAMPLE 130.5.0.0 130.5.2.144 255.255.255.0 130.5.2.0 - Network address - Host address - Subnet Mask - Subnet 27
Occupation of the address space 28
In classful addressing the address space is divided into 5 classes: A, B, C, D, and E. 29
Finding the class in binary notation 30
Finding the address class 31
Example 5 Show that Class A has 2 31 = 2,147,483,648 addresses 32
Example 6 Find the class of the following IP addresses 00000001 00001011 00001011 11101111 11000001 00001011 00001011 11101111 Solution 00000001 00001011 00001011 11101111 1 st is 0, hence it is Class A 11000001 00001011 00001011 11101111 1 st and 2 nd bits are 1, and 3 rd bit is 0 hence, Class C 33
Finding the class in decimal notation 34
Example 7 Find the class of the following addresses 158.223.1.108 227.13.14.88 Solution 158.223.1.108 1 st byte = 158 (128<158<191) class B 227.13.14.88 1 st 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 36
Netid and hostid 37
Blocks in class A 38
Millions of class A addresses are wasted. 39
Blocks in class B 40
Many class B addresses are wasted. 41
Blocks in class C 42
The number of addresses in a class C block is smaller than the needs of most organizations. 43
Class D addresses are used for multicasting; there is only one block in this class. 44
Class E addresses are reserved for special purposes; most of the block is wasted. 45
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. 47
Example 8 Given the network address 132.21.0.0, find the class, the block, and the range of the addresses Solution The 1 st 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 49
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 51
SUBNETTING 52
IP addresses are designed with two levels of hierarchy. 53
A network with two levels of hierarchy (not subnetted) 54
A network with three levels of hierarchy (subnetted) 55
THE INTERNET PROTOCOL Running out!! Upgraded to IPv6 56
QUESTIONS/COMMENTS? 57