MultiCloud Classroom notes 03/Dec/2025

subnetting

• private cidr ranges
  • 192.168.0.0/16
  • 10.0.0.0/8
  • 172.16.0.0/12

Example 3

• I need 4 subnets of 120 each
• Total nework ~= 500

2^n - 2 ~= 500
n = 9
N = 32 - 9 = 23

Network Range: 172.16.0.0/23
Network SM: 11111111.11111111.11111110.00000000

• subnet = 120

2^n  ~= 120
n = 7
N = 32 - 7 = 25
subnet SM: 11111111.11111111.11111111.10000000

• Combine

Network SM: 11111111.11111111.11111110.00000000
subnet SM:  11111111.11111111.11111111.10000000
------------------------------------------------------
                 172.      16.0000000x.x0000000/25
                 172.      16.00000000.00000000/25 = 172.16.0.0/25
                 172.      16.00000000.10000000/25 = 172.16.0.128/25
                 172.      16.00000001.00000000/25 = 172.16.1.0/25
                 172.      16.00000001.10000000/25 = 172.16.1.128/25

Example 4:

• I need 8 subnets of 12000 devices each
• Total devices = 12000 * 8 = 96000 ~= 1 lakh devices
• Network

2^n -2 ~= 100000
n = 17
N = 32 -17 = 15

range : 10.0.0.0/15
NSM: 11111111.11111110.00000000.00000000

• Subnet

2^n - 2 ~ = 12000
n = 14
N = 32 - 14 = 18

SSM: 11111111.11111111.11000000.00000000

• Combine

NSM: 11111111.11111110.00000000.00000000
SSM: 11111111.11111111.11000000.00000000
    ------------------------------------------
           10.0000000x.xx000000.0/18
           10.00000000.00000000.0/18  = 10.0.0.0/18
           10.00000000.01000000.0/18  = 10.0.64.0/18
           10.00000000.10000000.0/18  = 10.0.128.0/18
           10.00000000.11000000.0/18  = 10.0.192.0/18
           10.00000001.00000000.0/18  = 10.1.0.0/18
           10.00000001.01000000.0/18  = 10.1.64.0/18
           10.00000001.10000000.0/18  = 10.1.128.0/18
           10.00000001.11000000.0/18  = 10.1.192.0/18

Example 5: I want 16 subnets of size 50 each

• network:

2^n -2 ~= 16 * 50 = 800 = 10
n = 10
N = 22


192.168.0.0/22

• subnet

2^n - 2 ~ = 50
n = 6
N = 26

• combine:

NSM: 11111111.11111111.11111100.00000000
SSM: 11111111.11111111.11111111.11000000
-------------------------------------------
          192.     168.000000xx.xx000000/26
          192.     168.00000000.00000000/26 = 192.168.0.0/26
          192.     168.00000000.01000000/26 = 192.168.64.0/26
          192.     168.000000xx.xx000000/26 = 192.168.128.0/26
          192.     168.000000xx.xx000000/26 = 192.168.192.0/26
                                            = 192.168.1.0/26
          ...                               = 192.168.1.64.0/26
                                              ...