The document discusses IP addressing and subnetting. It explains that an IP address consists of 32 bits and can be represented in dotted-decimal, binary, or hexadecimal notation. The 32-bit address is divided into four octets. Subnetting allows a network administrator to create multiple logical subnets within a single IP network by borrowing bits from the host field of the address and designating them as the subnet field. The document provides an example of how to determine the subnet mask size, create subnets, and calculate subnet, host, and broadcast addresses when subnetting a network.

1. The Hierarchical IP Addressing
Scheme
IP address consists of 32 bits of information.
You can depict an IP address using one of three methods:
Dotted-decimal, as in 172.16.30.56
Binary, as in
10101100.00010000.00011110.00111000
Hexadecimal, as in AC.10.1E.38
11/11/14 OIT,RMUTT. 1

2. Octets
• The 32-bit IP address is broken up into 4
octets, which are arranged into a dotted-decimal
notation scheme.
• An octet is a set of 8 bits
• Example of an IP version 4:
172.64.126.52

3. IP Address as a
32-Bit Binary Number

4. Binary and Decimal Conversion

5. IP Address Classes

6. IP Address Classes

7. IP Addresses as Decimal Numbers

8. Hosts for Classes of
IP Addresses
Class A (24 bits for hosts) 224 - 2* = 16,777,214 maximum hosts
Class B (16 bits for hosts) 216 - 2* = 65,534 maximum hosts
Class C (8 bits for hosts) 28 - 2* = 254 maximum hosts
* Subtracting the network and broadcast reserved address

9. IP Addresses as Decimal Numbers

10. Network IDs and Broadcast
Addresses
An IP address such as 176.10.0.0 that has all binary 0s in the host
bit positions is reserved for the network address.
An IP address such as 176.10.255.255 that has all binary 1s in the
host bit positions is reserved for the broadcast address.

11. Private Addresses

12. Reserved Address Space
• Network ID
• Broadcast address
• Hosts for classes of IP addresses

13. Basics of Subnetting
• Classical IP addressing
• Subnetworks
• Subnet mask
• Boolean operations: AND, OR, and NOT
• Performing the AND function

14. Subnetworks
To create a subnet address, a network administrator
borrows bits from the original host portion and
designates them as the subnet field.

15. Subnetworks

16. Subnet Mask
• Determines which part of an IP address is the network
field and which part is the host field
• Follow these steps to determine the subnet mask:
– 1. Express the subnetwork IP address in binary form.
– 2. Replace the network and subnet portion of the address
with all 1s.
– 3. Replace the host portion of the address with all 0s.
– 4. Convert the binary expression back to dotted-decimal
notation.

17. Subnet Mask
Subnet mask in decimal = 255.255.240.0

18. Boolean Operations:
AND, OR, and NOT
• AND is like multiplication.
• OR is like addition.
• NOT changes 1 to 0, and 0 to 1.

19. Range of Bits Needed to Create
Subnets

20. Subnet Addresses

21. Decimal Equivalents of 8-Bit Patterns

22. Creating a Subnet
• Determining subnet mask size
• Computing subnet mask and IP address
• Computing hosts per subnetwork
• Boolean AND operation
• IP configuration on a network diagram
• Host and subnet schemes
• Private addresses

23. Determining Subnet Mask Size
Class B address with 8 bits borrowed for the subnet
130.5.2.144 (8 bits borrowed for subnetting) routes to subnet
130.5.2.0 rather than just to network 130.5.0.0.

24. Determining Subnet Mask Size
Class C address 197.15.22.131 with a subnet mask of
255.255.255.224 (3 bits borrowed)
11000101 00001111 00010110 100 00011
Network Field SN Host
Field
The address 197.15.22.131 would be on the subnet
197.15.22.128.

25. Subnetting Example
with AND Operation

26. Host Subnet Schemes
The number of lost IP addresses with a Class C network depends on
the number of bits borrowed for subnetting.

27. Working with Addresses (The Easy
Way)
• The key is to work in octets, rather than trying to
work with the entire IP address at once!

28. Subnetting Exercise
• What would be the case if the Network Administrator were
given the following network address 192.12.8.0, and the
number of departments were 7.
• 1. What class is the network address?
• 2. How many subnets are needed?
• 3. How many bits are borrowed from the host part of the address?
• 4. How many subnets are defined and how many of these are useable?
• 5. What is the default subnet mask?
• 6. What is the new customised subnet mask?
• 7. What is the decimal value of each subnet?
• 8. What is the total number of hosts?

29. Subnetting
• 1. What class is the network address?
– Class C as it is above 191
• 2. How many subnets are needed?
– 7 subnets -why not use just 3 bits
• 3. How many bits are borrowed from the host part of the address?
– 4 bits are needed
• 4. How many subnets are defined and how many of these are useable?
– 2 x 2 x 2 x 2 = 16 are defined - 16 - 2 = 14 are useable
• 5. What is the default subnet mask?
– 255.255.255.0 class C
• 6. What is the new customised subnet mask?
– 255.255.255.240

30. Subnetting a Class C Network
• First you must determine the reason you
are subnetting a network.
• There are many reasons. We will choose
one.
• If we put all 254 hosts on this one major
network, and the bandwidth is 100 Mbps,
each host will have approximately 393,700
bps of bandwidth (~394 kbps)

31. Subnetting a Class C Network
• Suppose that we wish to give 4 Mbps of
bandwidth to each user,
• Then we will subnet the network and put a
maximum of 25 users on each subnet.

32. Subnetting a Class C Network
• Aim: maximum of 25 users or hosts
• Add 2 the the total number of users.
• Write this chart.
128 64 32 16 8 4 2 1
It is the same chart we used earlier for
number conversions.

33. Subnetting a Class C Network
• Locate between which two numbers where
27 is located.
128 64 32 16 8 4 2 1
^
27 is located between 16 and 32.
Note: After adding 2 to the number of workstations and the
result is 4, 16, 32, 64, etc, draw the line to the right of that
number.

34. Subnetting a Class C Network
• Draw a line between 16 and 32 as shown.
128 64 32 | 16 8 4 2 1
|
The three bits left of the vertical line will be
used for the subnetwork number.
The five bits to the right of the line will be
used for the host address.

35. Subnetting a Class C Network
• Place 1s below the three bots to the left of
the line
• Place 0s below the five bits to the right of
the line
128 64 32 | 16 8 4 2 1
1 1 1 | 0 0 0 0 0
Remember, this is the fourth octet.

36. Determining the Subnet Mask
• The default mask for a class C address is
255.255.255.0
• The 255.255.255 identifies the part of the
subnet mask used for identifying the
network portion of the IP address
• The .0 identifies the host portion of the IP
address.

37. Determining the Subnet Mask
• Start by writing the first three octets for the
subnet mask: 255.255.255.
• Now calculate the subnet mask number for
the fourth octet
128 64 32 | 16 8 4 2 1
1 1 1 | 0 0 0 0 0
128 + 64 + 32 = ?

38. Determining the Subnet Mask
• Start by writing the first three octets for the
subnet mask: 255.255.255.
• Now calculate the subnet mask number for
the fourth octet
128 64 32 | 16 8 4 2 1
1 1 1 | 0 0 0 0 0
128 + 64 + 32 = 224
Therefore the subnet mask is
255.255.255.224

39. Addresses
• The last steps.
• Calculate each subnet address
• Calculate the 1st host address
• Calculate the last host address
• Calculate the broadcast address for each
subnetwork

40. Addresses
• The first subnetwork address is always 0.
192.1.2.0
• For this example, the subnetwork address
will increment by 32. 32 is the smallest
part of the subnetwork address.
128 64 32 | 16 8 4 2 1
1 1 1 | 0 0 0 0 0

41. Subnet Addresses
128 64 32 | 16 8 4 2 1
1 1 1 | 0 0 0 0 0
Subnet Addresses
0- 192.1.2.0 4- 192.1.2.128
1- 192.1.2.32 5- 192.1.2.160
2- 192.1.2.64 6- 192.1.2.192
3- 192.1.2.96 7- 192.1.2.224

42. 1st Host Addresses
• The first host address is always the subnet
address plus 1.
• For example: 192.1.2.0 + 1 = 192.1.2.1
• Therefore the first host address is 192.1.2.1

43. 1st Host Addresses
128 64 32 | 16 8 4 2 1
x x x | 0 0 0 0 1
1st host Addresses
0- 192.1.2.1 4- 192.1.2.129
1- 192.1.2.33 5- 192.1.2.161
2- 192.1.2.65 6- 192.1.2.193
3- 192.1.2.97 7- 192.1.2.225

44. 1st Host Addresses
128 64 32 | 16 8 4 2 1
x x x | 0 0 0 0 1
1st host Addresses
0- 192.1.2.1 4- 192.1.2.129
1- 192.1.2.33 5- 192.1.2.161
2- 192.1.2.65 6- 192.1.2.193
3- 192.1.2.97 7- 192.1.2.225

45. Broadcast Addresses
• The broadcast address is always 1 less than
the next subnetwork address.
• For example, the broadcast address for
subnet 0 can be calculated by subtracting 1
from the next subnetwork address.
• 192.1.2.32 – 1 = ?
• Therefore the broadcast address for subnet
0 is 192.1.2.32 – 1 = 192.1.2.31

46. Broadcast Addresses
128 64 32 | 16 8 4 2 1
x x x | 1 1 1 1 1
1st host Addresses
0- 192.1.2.31 4- 192.1.2.159
1- 192.1.2.63 5- 192.1.2.191
2- 192.1.2.95 6- 192.1.2.223
3- 192.1.2.127 7- 192.1.2.255

47. Last Host Addresses
• The last set of addresses to calculate are
the the last available host addresses.
• Using the broadcast address for each
subnetwork, subtract 1 to obtain the last
host address.
• For example: broadcast address for subnet
0 is 192.1.2.31
• The last host address is 192.1.2.30

48. Last Host Addresses
128 64 32 | 16 8 4 2 1
x x x | 1 1 1 1 0
1st host Addresses
0- 192.1.2.30 4- 192.1.2.158
1- 192.1.2.62 5- 192.1.2.190
2- 192.1.2.94 6- 192.1.2.222
3- 192.1.2.126 7- 192.1.2.254

49. IPv4 versus IPv6
• IP version 6 (IPv6) has been defined and developed.
• IPv6 uses 128 bits rather than the 32 bits currently
used in IPv4.
• IPv6 uses hexadecimal numbers to represent the 128
bits.
IPv4