AWS Classroomnotes 27/Jul/2022

Networking Contd….

• If we consider only octets for network creations we have only few possibilities
  • 255.255.255.0 => 2^8-2 ~= 250
  • 255.255.0.0 => 2^16-2 ~= 65000
  • 255.0.0.0 => 2^24-2
• To Create networks, the older approach was to use Classful Networking.
  • Class A
  • Class B
  • Class C
  • Class D
  • Class E
    
• Lets consider subnet mask as a binary number

ip:   192.168.0.4
sm:   255.255.255.0
      11111111.11111111.11111111.00000000

• Now lets assume i want to create a network of size 500

2^n ~= 500
n (number of zeros) = 9
N (number of ones) = 32-9 = 23
sm: 11111111.11111111.11111110.00000000

• Lets find a subnet mask for a network of size 22

2^n ~= 22
n (number of zeros) = 5
N (number of ones) = 32-5 => 27
sm: 11111111.11111111.11111111.11100000
    255.255.255.224

x.x.x.x/27

• Lets find a subnet mask for
• 1,20,000 devices

2^n ~= 120000
n = 17
N = 32-17 = 15
SM: 11111111.11111110.00000000.00000000
    255.254.0.0
x.x.x.x/15

• 10 devices

2^n ~= 10
n = 4
N = 32-4 = 28 
SM: 11111111.11111111.11111111.11110000
    255.255.255.240
x.x.x.x/28

• 5000 devices

2^n ~= 5000
n = 13
N = 32 -13 = 19
SM: 11111111.11111111.11100000.00000000
    255.255.224.0
x.x.x.x/19

• CIDR Notation:

x.x.x.x/N 
 N = number of ones in subnet mask

• Lets expand a cidr notation

192.168.0.0/24
SM: 11111111.11111111.11111111.00000000

range => 192.168.0.0 - 192.168.0.255

192.168.0.0/22
SM: 11111111.11111111.11111100.00000000
    192.168.0.0 to 192.168.3.255

10.0.0.0/12
SM: 11111111.11110000.00000000.00000000
    10.0.0.0 to 10.15.255.255