AWS Classroom Series – 20/Mar/2021

Networking contd

• Lets create a private network of size 10000 devices

2^n ~= 10000
number of zeros = 14
number of ones = 32-14 = 18
subnet mask : 11111111.11111111.11000000.00000000
subnet mask: 255.255.192.0

• My private network can be from any of the cidr ranges
  • 10.0.0.0/8
  • 172.16.0.0/12
  • 192.168.0.0/16
• So the private network will be

192.168.0.0/18
or
10.0.0.0/18
or
172.16.0.0/18

• Lets create a private network of size 100000 devices

2^n ~= 100000
number of zeros => 17
number of ones => 32-17 = 15
to choose a range
10.0.0.0/15
or
172.16.0.0/15

• Now since we know how to create a network, we should also look into how to break the network into smaller networks called as subnets

Scenario-1: So lets start with the following scenario

• network
• network range

2^n ~= 1000
number of zeros = 10
number of ones = 32-10 =22
since this is private network
ip: 192.168.0.0/22
sm: 11111111.11111111.11111100.00000000
sm: 255.255.252.0

• Now we need to create subnets in this network. Each subnet size is 250 devices

2^n ~= 250
number of zeros = 8
number of ones = 32-8 = 24
sm: 11111111.11111111.11111111.00000000 
sm: 255.255.255.0

subnet sm : 11111111.11111111.11111111.00000000 
network sm: 11111111.11111111.11111100.00000000

for subnets we have two bits
xx
00
01
10
11

subnet1
00 => 192.168.0.0/24

subnet 2 =>
01 => 192.168.1.0/24

subnet 3 => 
10 => 192.168.2.0/24

subnet 4 =>
11 => 192.168.3.0/24

Scenario 2

• Network requirements
• network size is 4000

2^n ~= 4000
number of zeros (n) = 12
number of ones => 32-12 => 20

sm: 11111111.11111111.11110000.00000000
sm: 255.255.240.0

• Each subnet should have 1000 devices

2^n ~=1000
number of zeros (n) = 10
number of ones => 32-10 = 22
sm: 11111111.11111111.11111100.00000000

• Lets compare subnet mask of subnet and network

subnet:  11111111.11111111.11111100.00000000
network: 11111111.11111111.11110000.00000000
so positons
xx00

• Lets choose a private range for network

10.10.0.0/20

• Now lets try to come up with cidr ranges for the subnets

xx00
first subnet => 0000
subnet 1: 10.10.0.0/22

subnet2 => 0100 => 10.10.4.0/22

subnet3 => 1000 => 10.10.8.0/22

subnet4 => 1100 => 10.10.12.0/22

Scenario 3:

• Networking requirements
• network size is 300 devices

2^n ~= 300
number of zeros (n) = 9
number of 1's will be 32-9 => 23

• network cidr range and subnet mask

ip: 192.168.0.0/23
sm: 11111111.11111111.11111110.00000000
sm: 255.255.254.0

• each subnet should be of size 50

2^n ~= 50
n = 6 => 
number of ones => 32-6 => 26

• subnet mask of each subnet will be

sm: 11111111.11111111.11111111.11000000

• now lets compare subnet mask of network and subnet

subnet : 11111111.11111111.11111111.11000000
network: 11111111.11111111.11111110.00000000
x.xx000000

• if we have 3 positions

xxx
000
001
010
011
100
101
110
111

• lets find cidr ranges for subnets

x.xx000000 
subnet 1 => 000=> 0.00000000 => 0.0 => 192.168.0.0/26
x.xx000000
subnet2=> => 001 =>0.01000000 => 0.64 => 192.168.0.64/26
x.xx000000
subnet 3 => 010 => 0.10000000 => 0.128 => 192.168.0.128/26
x.xx000000
subnet 4 => 011 => 0.11000000 => 0.192 => 192.168.0.192/26
x.xx000000
subnet 5 => 100 => 1.00000000 => 1.0 => 192.168.1.0/26
x.xx000000
subnet 6 => 101 => 1.01000000 => 1.64 => 192.168.1.64/26

Scenario 4: Exercise

• Network requirements