CIDR Notation
x.x.x.x/N
N = number of network id bits
1. 10.10.0.0/24
N = 24 (24 bits for network id)
n = 32 -24 = 8 ( 8 bits for host id)
size = 2^n - 2 = 2^8 - 2 = 254
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2. 192.168.0.0/22
N = 22
n = 32 - 22 = 10
size = 2^10 - 2 = 1024 -2 = 1022
- Private ip ranges: Private ip ranges are fixed
- 192.168.0.0/16
192.168.0.0/16
N = 16
n = 32 -16 = 16
size = 2^16 -2 = 65534
ip = 192.168 .xxxxxxxx.xxxxxxxx
sip= 192.168 .00000000.00000000 = 192.168.0.0
eip= 192.168 .11111111.11111111 = 192.168.255.255
SM = 11111111.11111111.00000000.00000000
range = 192.168.0.0 to 192.168.255.255
10.0.0.0/8
N = 8
n = 32 - 8 = 24
size = 2^24 -2 = 16777214
ip = 10.xxxxxxxx.xxxxxxxx.xxxxxxxx/8
sip = 10.00000000.00000000.00000000 = 10.0.0.0
eip = 10.11111111.11111111.11111111 = 10.255.255.255
SM = 11111111.00000000.00000000.00000000
range = 10.0.0.0 to 10.255.255.255
172.16.0.0/12
N = 12
n = 32 - 12 = 20
size = 2^20 -2 = 1048574
ip = 172.16.0.0/12
172.0001xxxx.xxxxxxxx.xxxxxxxx
sip = 172.00010000.00000000.00000000 = 172.16.0.0
eip = 172.00011111.11111111.11111111 = 172.31.255.255
SM = 11111111.11110000.00000000.00000000
range = 172.16.0.0 to 172.31.255.255
- In any cloud we will be creating private networks
Examples
Scenario 1
- I want to create a network with 500 devices, create a private network
size = 500
2^n - 2 ~= 500
2^n ~= 500
n = 9 (number of host id bits)
N = 32 - 9 = 23
options: 172.16.0.0/12
192.168.0.0/16
10.0.0.0/8
ip = 192.168.0.0/23
= 192. 168.0000000x.xxxxxxxx
sip = 192. 168.00000000.00000000 = 192.168.0.0
eip = 192. 168.00000001.11111111 = 192.168.1.255
SM = 11111111.11111111.11111110.00000000
range = 192.168.0.0 to 192.168.1.255
Scenario 2
- I need a private network to connect 25 devices
size = 25
2^n - 2 ~= 25
n = 5
N = 32 -5 = 27
ip = 172.16.0.0/27
172. 16. 0.000xxxxx
sip 172. 16. 0.00000000 = 172.16.0.0
eip 172. 16. 0.00011111 = 172.16.0.31
SM = 11111111.11111111.11111111.11100000
- Exercise: Try creating private networks of sizes
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