1. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 1 Chapter 4 Objectives Upon completion you will be able to: IP Addresses: Classful Addressing Understand IPv4 addresses and classes Identify the class of an IP address Find the network address given an IP address Understand masks and how to use them Understand subnets and supernets

2. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 2 CONTENTS INTRODUCTION CLASSFUL ADDRESSING OTHER ISSUES SUBNETTING AND SUPERNETTING

3. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 3 4.1 INTRODUCTION The identifier used in the IP layer of the TCP/IP protocol suite to identify each device connected to the Internet is called the Internet address or IP address. An IP address is a 32-bit address that uniquely and universally defines the connection of a host or a router to the Internet. IP addresses are unique. They are unique in the sense that each address defines one, and only one, connection to the Internet. Two devices on the Internet can never have the same address. The topics discussed in this section include: Address Space Notation

4. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 4 An IP address is a 32-bit address. Note: 4.1 INTRODUCTION

5. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 5 The IP addresses are unique. Note: 4.1 INTRODUCTION

6. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 6 RULE: If a protocol uses N bits to define an address, the address space is 2 N because each bit can have two different values (0 and 1) and N bits can have 2 N values. The address space of IPv4 is 2 32 or 4,294,967,296. Note: 4.1 INTRODUCTION

7. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 7  표기법  2 진 표기법 (Binary Notation)  10 진 표기법 (Dotted-decimal notation) 01110101 10010101 00011101 11101010 4.1 INTRODUCTION

8. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 8 The binary, decimal, and hexadecimal number systems are reviewed in Appendix B. Note: 4.1 INTRODUCTION

9. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 9 Change the following IP addresses from binary notation to dotted-decimal notation. a. 10000001 00001011 00001011 11101111 b. 11000001 10000011 00011011 11111111 c. 11100111 11011011 10001011 01101111 d. 11111001 10011011 11111011 00001111 Example 1 Solution We replace each group of 8 bits with its equivalent decimal number (see Appendix B) and add dots for separation: a. 129.11.11.239 b. 193.131.27.255 c. 231.219.139.111 d. 249.155.251.15

10. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 10 Change the following IP addresses from dotted-decimal notation to binary notation. a. 111.56.45.78b. 221.34.7.82 c. 241.8.56.12d. 75.45.34.78 Example 2 Solution We replace each decimal number with its binary equivalent: a. 01101111 00111000 00101101 01001110 b. 11011101 00100010 00000111 01010010 c. 11110001 00001000 00111000 00001100 d. 01001011 00101101 00100010 01001110

11. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 11 Find the error, if any, in the following IP addresses: a. 111.56.045.78b. 221.34.7.8.20 c. 75.45.301.14d. 11100010.23.14.67 Example 3 Solution a. There are no leading zeroes in dotted-decimal notation (045). b. We may not have more than four numbers in an IP address. c. In dotted-decimal notation, each number is less than or equal to 255; 301 is outside this range. d. A mixture of binary notation and dotted-decimal notation is not allowed.

12. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 12 Change the following IP addresses from binary notation to hexadecimal notation. a. 10000001 00001011 00001011 11101111 b. 11000001 10000011 00011011 11111111 Example 4 Solution We replace each group of 4 bits with its hexadecimal equivalent (see Appendix B). Note that hexadecimal notation normally has no added spaces or dots; however, 0X (or 0x) is added at the beginning or the subscript 16 at the end to show that the number is in hexadecimal. a. 0X810B0BEF or 810B0BEF 16 b. 0XC1831BFF or C1831BFF 16

13. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 13 4.2 CLASSFUL ADDRESSING IP addresses, when started a few decades ago, used the concept of classes. This architecture is called classful addressing. In the mid-1990s, a new architecture, called classless addressing, was introduced and will eventually supersede the original architecture. However, part of the Internet is still using classful addressing, but the migration is very fast. The topics discussed in this section include: Recognizing Classes Netid and Hostid Classes and Blocks Network Addresses Sufficient Information Mask CIDR Notation Address Depletion

14. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 14  주소 공간 할당  클래스 주소 갯수 4.2 CLASSFUL ADDRESSING

15. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 15  이진 표기법으로 클래스 찾기 4.2 CLASSFUL ADDRESSING

16. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 16  클래스 주소 찾기 4.2 CLASSFUL ADDRESSING

17. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 17 How can we prove that we have 2,147,483,648 addresses in class A? Example 5 Solution In class A, only 1 bit defines the class. The remaining 31 bits are available for the address. With 31 bits, we can have 2 31 or 2,147,483,648 addresses.

18. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 18 Find the class of each address: a. 00000001 00001011 00001011 11101111 b. 11000001 10000011 00011011 11111111 c. 10100111 11011011 10001011 01101111 d. 11110011 10011011 11111011 00001111 Example 6 Solution See the procedure in Figure 4.4. a. The first bit is 0. This is a class A address. b. The first 2 bits are 1; the third bit is 0. This is a class C address. c. The first bit is 0; the second bit is 1. This is a class B address. d. The first 4 bits are 1s. This is a class E address..

19. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 19  10 진 표기법으로 클래스 찾기 4.2 CLASSFUL ADDRESSING

20. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 20 Find the class of each address: a. 227.12.14.87b.193.14.56.22c.14.23.120.8 d. 252.5.15.111e.134.11.78.56 Example 7 Solution a. The first byte is 227 (between 224 and 239); the class is D. b. The first byte is 193 (between 192 and 223); the class is C. c. The first byte is 14 (between 0 and 127); the class is A. d. The first byte is 252 (between 240 and 255); the class is E. e. The first byte is 134 (between 128 and 191); the class is B.

21. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 21 In Example 5 we showed that class A has 2 31 (2,147,483,648) addresses. How can we prove this same fact using dotted- decimal notation? Example 8 Solution The addresses in class A range from 0.0.0.0 to 127.255.255.255. We need to show that the difference between these two numbers is 2,147,483,648. This is a good exercise because it shows us how to define the range of addresses between two addresses. We notice that we are dealing with base 256 numbers here. Each byte in the notation has a weight. The weights are as follows (see Appendix B):

22. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 22 256 3, 256 2, 256 1, 256 0 Example 8 Last address: 127 × 256 3 + 255 × 256 2 + 255 × 256 1 + 255 × 256 0 = 2,147,483,647 First address: = 0 Now to find the integer value of each number, we multiply each byte by its weight: If we subtract the first from the last and add 1 to the result (remember we always add 1 to get the range), we get 2,147,483,648 or 2 31.

23. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 23  Netid 와 Hostid 주소 4.2 CLASSFUL ADDRESSING

24. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 24  클래스 A 의 블록 4.2 CLASSFUL ADDRESSING

25. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 25 Millions of class A addresses are wasted. Note: 4.2 CLASSFUL ADDRESSING

26. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 26  클래스 B 의 블록 4.2 CLASSFUL ADDRESSING

27. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 27 Many class B addresses are wasted. Note: 4.2 CLASSFUL ADDRESSING

28. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 28  클래스 C 의 블록 4.2 CLASSFUL ADDRESSING

29. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 29 The number of addresses in class C is smaller than the needs of most organizations. Note: 4.2 CLASSFUL ADDRESSING

30. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 30 Class D addresses are used for multicasting; there is only one block in this class. Note: 4.2 CLASSFUL ADDRESSING

31. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 31 Class E addresses are reserved for future purposes; most of the block is wasted. Note: 4.2 CLASSFUL ADDRESSING

32. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 32 In classful addressing, the network address (the first address in the block) is the one that is assigned to the organization. The range of addresses can automatically be inferred from the network address. Note: 4.2 CLASSFUL ADDRESSING

33. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 33 Given the network address 17.0.0.0, find the class, the block, and the range of the addresses. Example 9 Solution The class is A because the first byte is between 0 and 127. The block has a netid of 17. The addresses range from 17.0.0.0 to 17.255.255.255.

34. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 34 Given the network address 132.21.0.0, find the class, the block, and the range of the addresses. Example 10 Solution The class is B because the first byte is between 128 and 191. The block has a netid of 132.21. The addresses range from 132.21.0.0 to 132.21.255.255.

35. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 35 Given the network address 220.34.76.0, find the class, the block, and the range of the addresses. Example 11 Solution The class is C because the first byte is between 192 and 223. The block has a netid of 220.34.76. The addresses range from 220.34.76.0 to 220.34.76.255.

36. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 36  마스크 A mask is a 32-bit binary number that gives the first address in the block (the network address) when bitwise ANDed with an address in the block. 4.2 CLASSFUL ADDRESSING

37. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 37  마스킹 개념 4.2 CLASSFUL ADDRESSING

38. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 38  AND 연산 4.2 CLASSFUL ADDRESSING

39. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 39  디폴트 마스크 4.2 CLASSFUL ADDRESSING

40. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 40 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. Note: 4.2 CLASSFUL ADDRESSING

41. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 41 Given the address 23.56.7.91, find the beginning address (network address). Example 12 Solution The default mask is 255.0.0.0, which means that only the first byte is preserved and the other 3 bytes are set to 0s. The network address is 23.0.0.0.

42. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 42 Given the address 132.6.17.85, find the beginning address (network address). Example 13 Solution The default mask is 255.255.0.0, which means that the first 2 bytes are preserved and the other 2 bytes are set to 0s. The network address is 132.6.0.0.

43. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 43 Given the address 201.180.56.5, find the beginning address (network address). Example 14 Solution The default mask is 255.255.255.0, which means that the first 3 bytes are preserved and the last byte is set to 0. The network address is 201.180.56.0.

44. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 44 Note that we must not apply the default mask of one class to an address belonging to another class. Note: 4.2 CLASSFUL ADDRESSING

45. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 45 4.3 OTHER ISSUES In this section, we discuss some other issues that are related to addressing in general and classful addressing in particular. The topics discussed in this section include: Multihomed Devices Location, Not Names Special Addresses Private Addresses Unicast, Multicast, and Broadcast Addresses

46. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 46  멀티홈드 장치  서로 다른 네트워크에 연결된 하나의 컴퓨터 4.3 OTHER ISSUES

47. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 47  특수주소 4.3 OTHER ISSUES

48. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 48  네트워크 주소 4.3 OTHER ISSUES

49. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 49  직접 브로드캐스트 주소  direct broadcast address  hostid 가 모두 “1” 인 주소  라우터가 특정 네트워크에 있는 모든 호스트에 패 킷을 보낼 때 사용  IP 패킷에서 목적지 주소로만 사용 4.3 OTHER ISSUES

50. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 50  직접 브로드 캐스트 주소 예 4.3 OTHER ISSUES

51. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 51  제한된 브로드캐스트 주소  limited broadcast address  현재 네트워크내에서 브로드캐스트 주소  로컬 네트워크내의 모든 호스트에게 메시지 전달 때 사용  다른 네트워크로 가는 것을 라우터가 제한함  클래스 E 주소 4.3 OTHER ISSUES

52. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 52  제한된 브로드 캐스트 주소 예 4.3 OTHER ISSUES

53. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 53  현재 네트워크에 있는 호스트  IP 주소가 모두 “0” 인 주소  this host on this network  IP 주소를 모르는 호스트가 bootstrap 시 사용  발신지 주소로만 이용  목적지 주소는 제한된 브로드캐스트 주소 이용  항상 클래스 A 주소 4.3 OTHER ISSUES

54. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 54  현재 네트워크에 있는 호스트 예 4.3 OTHER ISSUES

55. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 55  현재 네트워크에 있는 특정 호스트  netid 가 모두 “0” 인 주소  같은 네트워크에 있는 다른 호스트에게 메시지 보낼 때 사용 4.3 OTHER ISSUES

56. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 56  루프백 주소  loopback address  첫 번째 바이트가 “127” 인 IP 주소  컴퓨터에 설치된 소프트웨어를 시험하기 위해 사용  클라이언트 프로세스가 동일한 시스템상에 있는 서 버 프로세스에게 메시지 전송시 사용  IP 패킷의 목적지 주소로만 사용 4.3 OTHER ISSUES

57. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 57  루프백 주소의 예 4.3 OTHER ISSUES

58. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 58  사설 주소  사설 네트워크 주소 A number of blocks in each class are assigned for private use. They are not recognized globally. These blocks are depicted in Table 4.4 4.3 OTHER ISSUES

59. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 59  유니캐스트, 멀티캐스트, 브로드 캐스트 주소 Unicast communication is one-to-one. Multicast communication is one-to-many. Broadcast communication is one-to-all. 4.3 OTHER ISSUES

60. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 60 Multicast delivery will be discussed in depth in Chapter 15. Note: 4.3 OTHER ISSUES

61. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 61  범주 주소 (Category address) 4.3 OTHER ISSUES

62. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 62  회의용 주소 (Address for Conferencing) 4.3 OTHER ISSUES

63. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 63 4.3 OTHER ISSUES  인터넷 예

64. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 64 4.4 SUBNETTING AND SUPERNETTING In the previous sections we discussed the problems associated with classful addressing. Specifically, the network addresses available for assignment to organizations are close to depletion. This is coupled with the ever-increasing demand for addresses from organizations that want connection to the Internet. In this section we briefly discuss two solutions: subnetting and supernetting. The topics discussed in this section include: SubnettingSupernetting Supernet Mask Obsolescence

65. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 65  하나의 네트워크를 자신의 서브네트워크 주소 를 가진 여러 개의 서브넷 (Subnet) 으로 나눌 수 있다. IP addresses are designed with two levels of hierarchy. Note: 4.4 SUBNETTING AND SUPERNETTING

66. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 66  두 단계 계층 구조를 갖는 네트워크 4.4 SUBNETTING AND SUPERNETTING

67. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 67  3 단계 계층구조를 갖는 네트워크 ( 서브넷 ) 4.4 SUBNETTING AND SUPERNETTING

68. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 68  서브넷을 갖는 네트워크와 갖지 않는 네트워크 주소 지정 4.4 SUBNETTING AND SUPERNETTING

69. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 69  3 단계 계층 구조 4.4 SUBNETTING AND SUPERNETTING

70. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 70  마스킹 (Masking)  IP 주소중에서 네트워크 주소를 알아내기 위해 마스크 이용 (1- netid, 0-hostid) 4.4 SUBNETTING AND SUPERNETTING

71. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 71 Finding the Subnet Address Given an IP address, we can find the subnet address the same way we found the network address in the previous chapter. We apply the mask to the address. We can do this in two ways: straight or short-cut. 4.4 SUBNETTING AND SUPERNETTING

72. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 72 Straight Method In the straight method, we use binary notation for both the address and the mask and then apply the AND operation to find the subnet address. 4.4 SUBNETTING AND SUPERNETTING

73. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 73 What is the subnetwork address if the destination address is 200.45.34.56 and the subnet mask is 255.255.240.0? Example 15 Solution We apply the AND operation on the address and the subnet mask. Address ➡ 11001000 00101101 00100010 00111000 Subnet Mask ➡ 11111111 11111111 11110000 00000000 Subnetwork Address ➡ 11001000 00101101 00100000 00000000.

74. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 74 Short-Cut Method ** If the byte in the mask is 255, copy the byte in the address. ** If the byte in the mask is 0, replace the byte in the address with 0. ** If the byte in the mask is neither 255 nor 0, we write the mask and the address in binary and apply the AND operation. 4.4 SUBNETTING AND SUPERNETTING

75. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 75 Example What is the subnetwork address if the destination address is 19.30.80.5 and the mask is 255.255.192.0? Solution See Next Page 4.4 SUBNETTING AND SUPERNETTING

76. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 76  예제의 서브넷 4.4 SUBNETTING AND SUPERNETTING

77. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 77  디폴트 마스크와 서브넷 마스트 비교 4.4 SUBNETTING AND SUPERNETTING

78. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 78  슈퍼네트워크 4.4 SUBNETTING AND SUPERNETTING

79. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 79 In subnetting, we need the first address of the subnet and the subnet mask to define the range of addresses. In supernetting, we need the first address of the supernet and the supernet mask to define the range of addresses. Note: 4.4 SUBNETTING AND SUPERNETTING

80. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 80 Figure4.27 Comparison of subnet, default, and supernet masks 4.4 SUBNETTING AND SUPERNETTING

81. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 81 The idea of subnetting and supernetting of classful addresses is almost obsolete. Note: 4.4 SUBNETTING AND SUPERNETTING

82. HANNAM UNIVERSITY Http://netwk.hannam.ac.kr 82 연습문제 풀이해서 Report 로 다음주까지 ( 일주일 후 ) 제출해 주세요 ! 알림