The document discusses subnetting a large network with the IP address 200.1.2.0 into four smaller subnets. It provides the subnet mask and IP address range for each of the four subnets created. It also discusses the differences between fixed length and variable length subnetting. In another example, it shows how to calculate the subnet mask, block size, usable hosts, and network IDs when given the IP address 192.168.1.0/25.

1. Md.Mehedi Hassan
Programmer
Export Promotion Bureau
Ministry of commerce

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3. • The process of dividing a single network into multiple sub networks.
• It increases routing efficiency, which helps to enhance the security of
the network and reduces the size of the broadcast domain.
Big network Division of network into 4 subnets
Subnetting
Subnets

4. • The We have a big single network having IP Address: 200.1.2.0
• We want to do subnetting and divide this network into 4 subnets.
Subnetting
Division of network into 4 subnets
200.1.2.00000000 = 200.1.2.0
200.1.2.01000000 =
200.1.2.64
200.1.2.10000000 =
200.1.2.128
200.1.2.11000000 =
200.1.2.192
Big network

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7. • Fixed length subnetting also called
as classful subnetting
• All the subnets are of same size.
• All the subnets have equal number
of hosts.
• All the subnets have same subnet
mask
A=100
255.255.255.0
B=100
255.255.255.0
C=100
255.255.255.0
D=100
255.255.255.0

8. • Fixed length subnetting also called
as classless subnetting
• All the subnets are not same size.
• All the subnets do not have equal
number of hosts.
• All the subnets do not have same
subnet mask
A=4000
255.255.240.0
B=500
255.255.254.0
C=1000
255.255.252.0
D=200
255.255.255.0

9. Formula:
Requirement of Networks <=2𝑁 = 2𝑁𝑒𝑡𝑤𝑜𝑟𝑘 𝑏𝑖𝑡
Requirement of Host <=2ℎ-2= 2ℎ𝑜𝑠𝑡 -2
Block Size=2ℎ-2= 2ℎ𝑜𝑠𝑡
Example-
Ip address 192.168.1.0/25
Find the
a. Subnet mask
b. Block size
c. Network Id/subnet
d. Usable host each subnet
Big network
Subnetting

10. 255.255.255.128
11111111.11111111.11111111.1000000
192.168.1.0/25
Network bit=1 and host bit=7
Subnet Mask
1. Subnet Mask 255.255.255.128
2. Network 21
=2
3. Block Size 27
=128
4. Host 27
-2=128-2=126
Network
ID/Subnet
1st Host Last Host Broadcast ID
192.168.1.0 192.168.1.1 192.168.1.126 192.168.1.127
192.168.1.128 192.168.1.129 192.168.1.254 192.168.1.256
192.168.1.256
+128
+128

11. Example-
Ip address 192.16.0.0
Find the
a. Subnet mask
b. Block size
c. Network Id/subnet
Steps:
1. Host are ordered on decending
2. Find the host requirements
3. Find network and host bit
4. Find the block size
A=4000 B=500
C=1000
D=200

12. 255.255.240.0
11111111.11111111.11110000.0000000
Host bit 12
Host bit 12
1. Ordering host descending A=4000, D=1000,
B=500 and C=200
• Host A=4000
• Host requirements=𝟐𝟏𝟏
-2=2046≪ 𝟒𝟎𝟎𝟎
• Host requirements=𝟐𝟏𝟐
-2=4094≅ 𝟒𝟎𝟎𝟎
• Host bit is 12.
• Network id 172.16.0.0/20
• Subnet Mask 255.255.240.0
Network bit 20
Subnet

13. md.mehedi hassan
mehedi.ict08@gmail.com