SubNiting

Example 1 :

Device A: 172.16.17.30/20

Device B: 172.16.28.15/20

Determining the Subnet for Device A:

172.16.17.30  -   10101100.00010000.00010001.00011110

255.255.240.0 -   11111111.11111111.11110000.00000000

                  -----------------| sub|------------

subnet =          10101100.00010000.00010000.00000000 = 172.16.16.0

Determining the Subnet for Device B:

172.16.28.15  -   10101100.00010000.00011100.00001111

255.255.240.0 -   11111111.11111111.11110000.00000000

                  -----------------| sub|------------

subnet =          10101100.00010000.00010000.00000000 = 172.16.16.0

Example 2 :

Network ID:  192.168.1.0

SubNet MASK :  255.255.255.0

New SubNet MASK :  255.255.255.128

Bits Borrowed :   192.168.1.1|0000000

# Of possible networks: 2

Solution :

SubNetwork 1:  192.168.1.0

First valid IP:  192.168.1.1 

Last valid IP:  192.168.1.126 

Broadcast:  192.168.1.127

SubNetwork 2:  192.168.1.128 

First valid IP:  192.168.1.129 

Last valid IP:  192.168.1.254

Broadcast:  192.168.1.255