1. 21-IP addressing Dr. John P. Abraham Professor UTPA

2. Chapters 19, 20 I have already covered these concepts elsewhere.

3. Addressing Physical Logical

4. IP address 32 bits –Hierarchy – prefix and suffix –Prefix identifies the network – given by IANA 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. –Suffix identifies the computer –given locally –No two computers can have the same public IP

5. Classful IP addressing Divided IP address space into three primary classes A, B, C and also there exist class D (multicasting) and E. First four (MSB) bits will determine its class

6. Class Lea ding Bits Size of Network Number Bit field Size of Rest Bit field Number of Networks Addresse s per Network Start addres s End address Class A 0 8 24 128 (2 7 ) 16,777, 216 (2 24 ) 0.0.0.0127.255. 255.255 Class B 01 16 16,384 (2 14 ) 65,536 (2 16 ) 128.0.0. 0 191.255. 255.255 Class C 110 24 8 2,097,1 52 (2 21 ) 256 (2 8 )192.0.0. 0 223.255. 255.255 Class D (multicast)multicast 1110 not defined 224.0.0. 0 239.255. 255.255 Class E (reserved) 1111 not defined 240.0.0. 0 255.255. 255.255

7. Finding the address class

8. Figure 4.5 Finding the class in decimal notation

9. 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 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.

10. Subnet Addressing 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.

11. 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.

12. 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.

13. Figure 4.25 Comparison of a default mask and a subnet mask

14. Table 4.3 Special addresses Private IPs

15. CIDR notation Classless Inter-Domain routing (CIDR)

16. CIDR CIDR is an alternative to traditional IP subnetting that organizes IP addresses into subnetworks independent of the value of the addresses themselves. CIDR is also known as supernetting as it effectively allows multiple subnets to be grouped together for network routing. Ddd.ddd.ddd.ddd/m 192.5.48.69/26

17. CIDR Prefix length is given after the slash 230.8.24.56/16 gives block of 230.8.0.0 to 230.8.255.255 To find the first address AND the mask. To find the last address, find the complement of the mask, then OR.

18. CIDR example One of the address in a block is 17.63.110.114/24. Find the number of address, the first address, and the last address of the block. 17 63 110 114 255 255 255 0 AND 17 63 110 0 IS THE FIRST ADDRESS --- 17 63 110 114 0 0 0 255 OR 1763 110 255 IS THE LAST ADDRESS

19. CIDR example 110.23.120.14.20. Find the first and last address 110 23 120 14 255 255 240 0 AND 110 23 112 0 110 23 120 14 0 0 15 255 OR 110 23 127 255 LAST ADDRESS