LECTURE -4 IP ADDRESSES. IP Addresses: Classful Addressing

Transcription

1 LECTURE -4 IP ADDRESSES IP Addresses: Classful Addressing 1

2 CONTENTS INTRODUCTION CLASSFUL ADDRESSING Different Network Classes Subnetting Classless Addressing 2

3 INTRODUCTION 3

4 WHAT IS AN IP ADDRESS A way to identify machines on a network A unique identifier 4

5 IP USAGE Used to connect to another computer Allows transfers of files and 5

6 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,

7 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

8 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

9 IP STRUCTURE Class D are reserved for multicasting Class E are reserved for future use 9

10 IP STRUCTURE Class A begins 1 to 126 Class B begins 128 to 191 Class C begins 192 to

11 What is an IP Address? An IP address is a 32-bit address. The IP addresses are unique. 11

12 Address Space.. addr1.. addr15 addr addr41 addr226 addr

13 Address space rule.. addr1.. addr15 The addr2 address.. space in a protocol.. That.. uses N-bits to define an Address is: addr41 addr226 addr N.. 13

14 IPv4 address space The address space of IPv4 is 2 32 or 4,294,967,

15 Binary Notation

16 Dotted-decimal notation 16

17 Hexadecimal Notation D EA 0x75951DEA 17

18 Example 1 Change the following IP address from binary notation to dotted-decimal notation Solution

19 Example 2 Change the following IP address from dotted-decimal notation to binary notation: Solution

20 Example 3 Find the error in the following IP Address Solution There are no leading zeroes in Dotted-decimal notation (045) 20

21 Example 3 (continued) Find the error in the following IP Address Solution In decimal notation each number <= is out of the range 21

22 Example 4 Change the following binary IP address Hexadecimal notation Solution 0X810B0BEF or 810B0BEF16 22

23 RESERVED ADDRESSES Addresses beginning 127 are reserved for loopback and internal testing xxx reserved for network address xxx reserved for broadcast 23

24 IP ADDRESSES IP addresses are: Unique Global and Standardised Essential 24

25 SUBNETTING - WHY? Division of local networks Greater number of networks Simplifies addressing 25

26 SUBNETTING - HOW Bits borrowed from host field Network Network Host Host Network Network Subnet Host Network Network Subnet Subnet/Host 26

27 SUBNETTING -EXAMPLE Network address - Host address - Subnet Mask - Subnet 27

28 Occupation of the address space 28

29 In classful addressing the address space is divided into 5 classes: A, B, C, D, and E. 29

30 Finding the class in binary notation 30

31 Finding the address class 31

32 Example 5 Show that Class A has 2 31 = 2,147,483,648 addresses 32

33 Example 6 Find the class of the following IP addresses Solution st is 0, hence it is Class A st and 2 nd bits are 1, and 3 rd bit is 0 hence, Class C 33

34 Finding the class in decimal notation 34

35 Example 7 Find the class of the following addresses Solution st byte = 158 (128<158<191) class B st byte = 227 (224<227<239) class D 35

36 IP ADDRESS WITH APPENDING PORT NUMBER :25 the for octet before colon is the IP address The number of colon (25) is the port number 36

37 Netid and hostid 37

38 Blocks in class A 38

39 Millions of class A addresses are wasted. 39

40 Blocks in class B 40

41 Many class B addresses are wasted. 41

42 Blocks in class C 42

43 The number of addresses in a class C block is smaller than the needs of most organizations. 43

44 Class D addresses are used for multicasting; there is only one block in this class. 44

45 Class E addresses are reserved for special purposes; most of the block is wasted. 45

46 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

47 In classful addressing, the network address (the first address in the block) is the one that is assigned to the organization. 47

48 Example 8 Given the network address , 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 The addresses range from to

49 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

50 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

51 DEFAULT MAK Class A default mask is Class B default mask is Class C Default mask

52 SUBNETTING 52

53 IP addresses are designed with two levels of hierarchy. 53

54 A network with two levels of hierarchy (not subnetted) 54

55 A network with three levels of hierarchy (subnetted) 55

56 THE INTERNET PROTOCOL Running out!! Upgraded to IPv6 56

57 QUESTIONS/COMMENTS? 57