Example 1: Classless Inter-Domain Routing (CIDR) (Super-netting)

Question:

Example 1

v  In NITT Campus,

For Admin we need 100 Host (Vlan name – Vlan A)

For Security – 100 Host (Vlan B)

Dean – 100 Host (Vlan C)

So totally we need 300 Host

Answer:

v  If we choose Class C, Last bit only Host. So we can choose maximum 255 Host only, but we need 300 Host. So we choose Class-B or Class-A

v Now We Choose Class-B to Solve

Sub-netting

v  We Never Use 0^th Subnet

1^st Subnet: (Vlan A)

1st Subnet

N/w ID: 172.16.0.128

1^st Host ID: 172.16.0.129

Last Host ID: 172.16.0.254

Broadcast ID: 172.16.0.255

Subnet Mask: 255.255.255.128

2^nd Subnet: (Vlan B)

2nd Subnet

N/w ID: 172.16.1.0

 (Previous Vlan next broadcast IP is this Vlan network id)

1^st Host ID: 172.16.1.1

Last Host ID: 172.16.1.126

Broadcast ID: 172.16.1.127

Subnet Mask: 255.255.255.128

3^rd Subnet: (Vlan C)

3rd Subnet

N/w ID: 172.16.1.128

1^st Host ID: 172.16.1.129

Last Host ID: 172.16.1.254

Broadcast ID: 172.16.1.255

Subnet Mask: 255.255.255.128