Azure Classroom notes 19/Oct/2023

Networking contd

• Expand CIDR

172.16.0.0/21
range:   172.      16.00000xxx.xxxxxxxx
start:   172.      16.00000000.00000000 = 172.16.0.0
end:     172.      16.00000111.11111111 = 172.16.7.255
SM: 11111111.11111111.11111000.00000000

• What is bigger network in this
  • A: 172.16.0.0/15 => 2 ^ (32-15) – 2 => 2^ 17
  • B: 192.168.0.0/17 => 2 ^ (32-17) – 2 => 2^15

Subnetting

• Subnet is smaller network.
• Subnetting is an activity of creating smaller networks from large network

Scenario – 1

• We need to create a network capable of 1000 devices and create 4 subnets with each capable of connecting 250 devices
  
• Network

2^n - 2 ~= 1000
n = 10
N = 32 - 10 = 22

cidr = 192.168.0.0/22

• Individual subnet

2^n - 2 ~= 250
n = 8
N = 32 - 8 = 24

• subnetting

SM (Network) = 11111111.11111111.11111100.00000000
SM (subnet)  = 11111111.11111111.11111111.00000000
      ---------------------------------------------
               11111111.11111111.111111xx.00000000
    Net ip          192.     168.00000000.       0 
    s1  ip          192.     168.00000000.        => 192.168.0.0/24
    s2  ip          192.     168.00000001.        => 192.168.1.0/24  
    s3  ip          192.     168.00000010.        => 192.168.2.0/24
    s4  ip          192.     168.00000011.        => 192.168.3.0/24

Scenario: Create a network with 2 subnets each of 5000 devices

• Overview
  
• Network

2^n - 2 ~= 10000
n = 14
N = 32 - 14 = 18

CIDR: 172.16.0.0/18

• Subnet

2^n-2 ~= 5000
n = 13
N = 32 - 13 = 19

• Subnetting

Network:  172.16.0.0/18
SM:    11111111.11111111.11000000.00000000
s-sm : 11111111.11111111.11100000.00000000
-------------------------------------------
                         00y00000.   
                         00000000      => 172.16.0.0/19
                         00100000      => 172.16.32.0/19

Scenario 3: Create 4 subnets with size to host 100 devices

• Problem
  
• Network

2^n ~= 400
n = 9
N = 32-9 = 23
10.0.0.0/23

• subnet

2^n -2 ~= 100
n = 7
N = 25

• Subnetting

ip:  10.0.0.0/23
N-SM: 11111111.11111111.11111110.00000000
s-SM: 11111111.11111111.11111111.10000000
      -----------------------------------
                        0000000y.y0000000
                        00000000.00000000 = 10.0.0.0/25
                        00000000.10000000 = 10.0.0.128/25
                        00000001.00000000 = 10.0.1.0/25
                        00000001.10000000 = 10.0.1.128/25

• Exercise: I need 8 subnets of 30,000 devices each i.e. total 2,40,000 devices