1. IP Subnetting (Week 4, Wednesday 1/31/2007) © Abdou Illia, Spring 2007

2. 2 Structure of IP addresses Network Part (n) Local Part (h) Class Annnnnnnn.hhhhhhhh.hhhhhhhh.hhhhhhhh10.0.0.1 – 126.255.255.255 Class Bnnnnnnnn.nnnnnnnn.hhhhhhhh.hhhhhhhh128.0.0.1 – 191.255.255.255 Class Cnnnnnnnn.nnnnnnnn.nnnnnnnn.hhhhhhhh192.0.0.1 – 223.255.255.255 Sgmt. partHost part

3. 3 Reserved IP addresses ClassRange A10.0.0.0 – 10.255.255.255 B172.16.0.0 – 172.31.255.255 C192.168.0.0 – 192.168.255.255 IP addresses reserved for private use. AddressUse 255.255.255.255 Example: 10.255.255.255 Local broadcast to LAN computers Broadcast to network 10.0.0.0/8 127.0.0.1Loopback address (for self addressing) 0.0.0.0Prohibited 169.254.x.xAutomatic Private IP Addressing Special IP addresses.

4. 4 Structure of IP addresses The division between Network part, Segment part, and Host part is determined by a computer or a router by using a network mask. Network Part Segment Part Host Part

5. 5 Network mask A 32 bit number, just like an IP address, where all bits in the Network Part and the Segment Part are set to 1, and all bits in the Host Part are set to 0. Example: 11111111 11111111 11111111 00000000 (or 255.255.255.0 in decimal notation) Computers use Network mask, along with the IP address, to determine whether or not a destination IP address is on the same logical network.

6. 6 Two Virtual LANs 192.168.1.1 255.255.255.0 192.168.1.2 255.255.255.0 192.168.1.3 255.255.255.0 192.168.2.1 255.255.255.0 192.168.2.2 255.255.255.0 192.168.2.3 255.255.255.0 Switch

7. 7 Two interconnected LANs

8. 8 The ADDing technique Are the following three Class C IP addresses from the same network? 192.168.1.1, 192.168.1.50 and 192.168.2.1 IP:110000001010100000000001 192.168.1.1 Mask:11111111 00000000255.255.255.0 Network:11000000101010000000000100000000192.168.1.0/24 IP:11000000101010000000000100110010192.168.1.50 Mask:11111111 00000000255.255.255.0 Network:11000000101010000000000100000000192.168.1.0/24 IP:11000000101010000000001000000001192.168.2.1 Mask:11111111 00000000255.255.255.0 Network:11000000101010000000001000000000192.168.2.0/24 128 64 32 16 8 4 2 1 Network 1: 192.168.1.0/24, i.e network starting at 192.168.1.0 with network mask 255.255.255.0. Network 2: 192.168.2.0/24, i.e network starting at 192.168.2.0 with network mask 255.255.255.0.

9. 9 Subnetting a class C network Suppose the 192.168.1.0/24 network You want to divide that network into two segments  You can decide to use the first bit of the fourth octet as dividing point between your network segments. So, your network mask would be: 11111111 11111111 11111111 10000000 And you will have about 2 7 = 128 hosts in each segment. 128 64 32 16 8 4 2 1 Segment 1: 192.168.1.0 to 192.168.1.127Segment 2: 192.168.1.128 to 192.168.1.255 How to determine the two segments using the ADDing technique?

10. 10 Subnetting a class C network IP:110000001010100000000001 192.168.1.1 Mask:11111111 10000000255.255.255.128 Network:11000000101010000000000100000000192.168.1.0/25........................ IP:11000000101010000000000101111111192.168.1.127 Mask:11111111 10000000255.255.255.128 Network:11000000101010000000000100000000192.168.1.0/25 128 64 32 16 8 4 2 1 Segment 1: 192.168.1.0 to 192.168.1.127

11. 11 Subnetting a class C network IP:11000000101010000000000110000000192.168.1.128 Mask:11111111 10000000255.255.255.128 Network:11000000101010000000000110000000192.168.1.128/25........................ IP:11000000101010000000000111111110192.168.1.254 Mask:11111111 10000000255.255.255.128 Network:11000000101010000000000110000000192.168.1.128/25 128 64 32 16 8 4 2 1 Segment 2: 192.168.1.128 to 192.168.1.255

12. 12 Question 1 Network A is IP network 192.168.1.x/24 (i.e a Class C network with a default 24-bit mask). Using the IP Subnet Calculator, determine the maximum number of hosts (computers) in each of the Network A’s subnets assuming that there are two subnets. You answer: ________. Using the IP Subnet Calculator, determine the maximum number of subnets for a Class B network assuming that the four first bits of the third octet in each IP address are used as subnet bits. Your answer: _____. What is the maximum number of computers for each subnet? Your answer: ______.

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