1. IP Subnetting

2. IP Addressing Introduction
IPv4 addresses are 32 bits in length.
IPv4 broken into four bytes (called octets), with a dot between each byte.
Classes of Addresses
Used for network
Class A
Class B
Class C
Multicast
Class D
Future
Class E

3. Decimal to Binary Numbers

4. IP Address Components
IP address has two part, the first part is the network which identifies the network where the system is connected, and a second part is the Host which identifies that particular system on the network.

5. Subnet Mask

6. Guidelines for IP Addressing
You must not use 127 for the first octet of the network ID. This value is reserved for diagnostic purposes.
You must not use all 1s (binary) for the host ID. If all bits are set to 1, the address is interpreted as a broadcast address.
You must not use all 0s for the host ID. If host bits are set to 0, some TCP/IP implementations interpret this as a subnetwork address.
You must not duplicate host IDs within a network segment.

7. Identifying IP Addresses
Determine which of the following IP addresses is valid or invalid
Invalid (256)
Valid
Invalid (127)
Invalid (Broadcast)

8. What Is a Subnet?
A subnet is a physical segment of a network that is separated from the rest of the network by a router or routers.
A network of multiple subnets connected by routers is often referred to as an internetwork.

9. Creating a Subnet How many subnets? How many hosts per subnet?
2X = number of subnets you need (X represents subnet bits)
How many hosts per subnet?
2Y - 2 = number of hosts (Y represents host bits)
What are the valid subnets?
256 – subnet mask
What’s the broadcast address for each subnet?
What are the valid hosts? Valid hosts are the numbers between the subnets, omitting all the 0s and all 1s.

10. Example 1 192.168.10.0 = Network address 255.255.255.192 = Subnet mask
How many subnets? Since 192 is 2 bits on ( ), the answer would be 22.
How many hosts per subnet? We have 6 host bits off ( ), so the equation would be 26 – 2 = 62 hosts.
What are the valid subnets? 256 – 192 = 64. Remember, we start at zero and count in our block size, so our subnets are 0, 64, 128, and 192.
What’s the broadcast address for each subnet? The number right before the value of the next subnet is all host bits turned on and equals the broadcast address.

11. Example 1 192 128 64 The subnets 193 129 65 1 The first host 254 190
What are the valid hosts?
192
128 64
The subnets
193
129 65 1
The first host
254
190
126 62
The last host
255
191
127 63
The broadcast address

12. Example 2 192.168.10.0 = Network address 255.255.255.224 = Subnet mask
How many subnets? 224 is , so our equation would be 23 = 8.
How many hosts? 25 – 2 = 30.
What are the valid subnets? 256 – 224 = 32. We just start at zero and count to the subnetmask value in blocks (increments) of 32: 0, 32, 64, 96, 128, 160, 192, 224.
What’s the broadcast address for each subnet (always the number right before the next subnet)?
What are the valid hosts (the numbers between the subnet number and the broadcast address)?

13. Example 2 The subnets The first host The last host The broadcast
What are the valid hosts?
224
192
160
128 96 64 32
The subnets
225
193
161
129 97 65 33 1
The first host
254
222
190
158
126 94 62 30
The last host
255
223
191
159
127 95 63 31
The broadcast
address

14. Exercise 1
You are given a Class C network ( ) and you have 4 segments in your network, where the largest segment has 50 hosts. What subnet mask should you use and what is the layout of your addresses?

15. Answer 1 Subnet Mask = 255.255.255.192 192 128 64 The subnets 193 129
The subnets
193
129 65 1
The first host
254
190
126 62
The last host
255
191
127 63
The broadcast address

16. Exercise 2
You are given the following address: /29. What type of address is this network, broadcast, or host?
Answer: -
This is a broadcast address.

17. Exercise 3
You are given the following address: /22. What type of address is this network, broadcast, or host?
Answer: -
This is a host address.

18. VLSM