1. IP Addresses: Classful Addressing
Lecture -2 IP Addresses
IP Addresses:
Classful Addressing

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

3. INTRODUCTION

4. What is an IP address A way to identify machines on a network
A unique identifier

5. IP usage Used to connect to another computer
Allows transfers of files and
If you want to connect to another computer, transfer files to or from another computer, or send an message, you first need to know where the other computer is - you need the computer's "address." An IP (Internet Protocol) address is an identifier for a particular machine on a particular network; it is part of a scheme to identify computers on the Internet. IP addresses are also referred to as IP numbers and Internet addresses

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,
An IP address consists of four sections separated by dots.
Commonly written in decimal Each section contains a number ranging from 0 to 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
These four sections represent both the machine itself, or host, and the network that the host is on. The network portion of the IP address is allocated under authority of the Internet Assigned Numbers Authority (IANA). American Registry of Internetwork Numbers (ARIN) Network administrators then assign the host portion of the IP address to the machines on the networks that they operate

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
Which sections of the IP address represent the network and which sections represent the machine will depend on what "class" of IP address is assigned to a network.
There are 5 classes of IP addresses: Class A, Class B, Class C, Class D, and Class E.
Class A - supports 16 million hosts on each of 127 networks
Class B - supports 65,000 hosts on each of 16,000 networks
Class C - supports 254 hosts on each of 2 million networks

9. IP structure Class D are reserved for multicasting
Class E are reserved for future use

10. IP structure Class A begins 1 to 126 Class B begins 128 to 191
Class C begins 192 to 223
Classes correspond either to the size of the network (the number of hosts that the network can support) or are reserved for specific purposes, such as multicasting and experimentation.
The diagram shows Class A, Class B and Class C IP addresses. The blue numbers represent the network and the red numbers represent hosts on the network. As has been mentioned, a Class A network can support many more hosts than a Class C network.
You can determine which class any IP address is in by examining the first 4 bits of the IP address.
Class A addresses begin with 0xxx, or 1 to 126 decimal.
Class B addresses begin with 10xx, or 128 to 191 decimal.
Class C addresses begin with 110x, or 192 to 223 decimal.
Class D addresses begin with 1110, or 224 to 239 decimal.
Class E addresses begin with 1111, or 240 to 254 decimal.
Addresses beginning with , or 127 decimal, are reserved for loopback and for internal testing on a local machine. [You can test this: you should always be able to ping , which points to yourself] Class D addresses are reserved for multicasting. Class E addresses are reserved for future use. They should not be used for host addresses.

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

12. Address Space ………….. addr1 addr15 addr2 ………….. ………….. ………….. addr226

13. Address space rule 2N ………….. addr1 addr15 addr2 …………..
The address space in a protocol
That uses N-bits to define an
Address is: 2N
…………..
…………..
…………..
addr41
addr226
addr31
…………..
…………..

14. The address space of IPv4 is
IPv4 address space
The address space of IPv4 is
or 4,294,967,296.

15. Binary Notation

16. Dotted-decimal notation

17. Hexadecimal Notation
D EA
0x75951DEA

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

21. Example 3 (continued) Solution
Find the error in the following IP Address
Solution
In decimal notation each number <= 255
301 is out of the range

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

23. Reserved addresses
Addresses beginning 127 are reserved for loopback and internal testing
xxx reserved for network address
xxx reserved for broadcast
Loopback
Routers use the network address in the forwarding of data. Also, Hosts can only communicate directly with devices using the same network address.
Broadcast allows a message to be sent to all devices on a network

24. IP Addresses IP addresses are: Unique Global and Standardised
Essential
IP addresses are unique. No two machines can have the same IP number. IP addresses are also global and standardized. All machines connected to the Internet agree to use the same scheme for establishing an address.

25. Subnetting - Why? Division of local networks
Greater number of networks
Simplifies addressing

26. Subnetting - How Bits borrowed from host field Network Host Network
Subnet/Host

27. Subnetting -Example 130.5.0.0 - Network address
Host address
Subnet Mask
Subnet

28. Occupation of the address space

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

30. Finding the class in binary notation

31. Finding the address class

32. Example 5
Show that Class A has
231 = 2,147,483,648 addresses

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

34. Finding the class in decimal notation

35. Solution Example 7 Find the class of the following addresses
Solution
1st byte = 158 (128<158<191) class B
1st byte = 227 (224<227<239) class D

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

37. Netid and hostid

38. Blocks in class A

39. Millions of class A addresses are wasted.

40. Blocks in class B

41. Many class B addresses are wasted.

42. Blocks in class C

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

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

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

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

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

48. Solution Example 8 Given the network address 132.21.0.0, find the
class, the block, and the range of the addresses
Solution
The 1st 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

50. The network address is the beginning address of each block
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.

51. Default Mak Class A default mask is 255.0.0.0
Class B default mask is
Class C Default mask

52. SUBNETTING

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

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

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

56. The Internet Protocol
Running out!!
Upgraded to IPv6

57. Questions/Comments?