VLSM Super netting

VLSM (Variable Length Subnet Mask)
Dividing the subnet into small subnet for efficiently utilize of address is called a VLSM or super netting, in one major network we have more than one subnet mask, inter department routing is not possible. 
* Subnetting a subnet is called as Variable Length Subnet Mask.
* VLSMs provide the capability to include more then one subnet mask within a major network.

Scenario:
* freetest hub is having 100 PC
    freetest hub - 192.168.1.0/24
`   -MCSE
    -CISCO
    -FIREWALL
    -SOLARIS
    -TRAINING
    Administrator's requirement: Inter-department cpmmunication should not be possible?
    Best Solution is : FLSM (i.e. Subnetting)
* Now we are also having sub department
1 MCSE 
2 CISCO
   a. CCNA
    b. CCNP
 3 FIREWALL
   a.  ISA
    b. Checkpont
    c. NetASQ
    d. Clavister
    e. Cisco PIX 
 4 SOLARIS   
    a. Linux
    b. Unix
    c. Solaris
5 TRAINING
Administrator does not want inter-department communication in the sub department?
ANSWER:
You  will use the subnet range to futher divide it nto smaller ranges, this time its Subnetting of a  Subnet i.e. VLSM.
Class C : N.N.N.H
Class C 192.168.1.0
No. of subnet
     = 2ⁿ-2 > Req. of subnet
     = 2³-2 > 2 (-2 is for First & Subnet Range)
     = 8-2
     =6 Subnet
No. of Host
     = 2^h-2 (-2 is for Network ID & Broadcast ID)
     = 2⁵-2
     = 32-2
     = 30 Host/Subnet
Customized subnet mask
255.255.255.224
Host Range
1 MCSE           =>192.168.1.32 - 1.63/27
2 CISCO           =>192.168.1.64 - 1.95/27
    ccna
    ccnp
3 FIREWALL =>192.168.1.96 - 1.127/27
         ISA    
         Checkpont
         NetASQ 
         Clavister 
          Cisco PIX 
4 SOLARIS    =>192.168.1.128 - 1.159/27
       Linux
       Unix
        Solaris
5 TRAINING =>192.168.1.160 - 1.191/27
Calculation of VLSM for CISCO Dept.
Class C : N.N.N.H
Class C 192.168.1.64
No. of subnet
     = 2ⁿ > Req. of subnet
     = 2¹ > 2
     = 2
     = 2 Subnet
No. of Host
     = 2^h-2 (-2 is for Network ID & Broadcast ID)
     = 2⁴-2
     = 16-2
     = 14 Host/Subnet
Customized subnet mask
255.255.255.240
Host Range
1 MCSE           =>192.168.1.32 - 1.63/27
2 CISCO           =>192.168.1.64 - 1.95/27
    ccna =>192.168.1.64 - 1.79/28
    ccnp =>192.168.1.80 - 1.95/28
3 FIREWALL =>192.168.1.96 - 1.127/27
4 SOLARIS    =>192.168.1.128 - 1.159/27
5 TRAINING =>192.168.1.160 - 1.191/27

Calculation of VLSM for Firewall Dept.
Class C : N.N.N.H
Class C 192.168.1.96
No. of subnet
     = 2ⁿ > Req. of subnet
     = 2³ > 5
     = 8
     = 8 Subnet
No. of Host
     = 2^h-2 (-2 is for Network ID & Broadcast ID)
     = 2²-2
     = 4-2
     = 2 Host/Subnet
Customized subnet mask
255.255.255.252
Host Range
1 MCSE  =>192.168.1.32 - 1.63/27
2 CISCO  =>192.168.1.64 - 1.95/27
                ccna =>192.168.1.64 - 1.79/28
                ccnp =>192.168.1.80 - 1.95/28
3 FIREWALL =>192.168.1.96 - 1.127/27
                      ISA          =>192.168.1.96 - 1.99/30
                     Checkpont=>192.168.1.100 - 1.103/30
                     NetASQ    =>192.168.1.104 - 1.107/30
                     Clavister    =>192.168.1.108 - 1.111/30
                     Cisco PIX  =>192.168.1.112 - 1.115/30
4 SOLARIS    =>192.168.1.128 - 1.159/27
5 TRAINING =>192.168.1.160 - 1.191/27

Calculation of VLSM for Solaris Dept.
Class C : N.N.N.H
Class C 192.168.1.128
No. of subnet
     = 2ⁿ > Req. of subnet
     = 2² > 3
     = 4
     = 4 Subnet
No. of Host
     = 2^h-2 (-2 is for Network ID & Broadcast ID)
     = 2³-2
     = 8-2
     = 6 Host/Subnet
Customized subnet mask
255.255.255.248
Host Range
1 MCSE  =>192.168.1.32 - 1.63/27
2 CISCO  =>192.168.1.64 - 1.95/27
                ccna =>192.168.1.64 - 1.79/28
                ccnp =>192.168.1.80 - 1.95/28
3 FIREWALL =>192.168.1.96 - 1.127/27
                      ISA          =>192.168.1.96 - 1.99/30
                     Checkpont=>192.168.1.100 - 1.103/30
                     NetASQ    =>192.168.1.104 - 1.107/30
                     Clavister    =>192.168.1.108 - 1.111/30
                     Cisco PIX  =>192.168.1.112 - 1.115/30
4 SOLARIS    =>192.168.1.128 - 1.159/27
                    Linux =>192.168.1.128 - 1.135/29
                    Unix =>192.168.1.136 - 1.143/29
                    Solaris =>192.168.1.144 - 1.151/29
5 TRAINING =>192.168.1.160 - 1.191/27