Subnetting Calculation

In this project, students are required to suggest private addressing scheme used in Cobham College IT Center. Explain how you calculate the subnetting using FLSM based on the number of the faculties. Each faculty is given their network address. Assign IT Center as another subnet with their own network address. From this network address, assigned as the 4th available address as the address of the Online Learning System Server. 

Students are allowed to do the addressing by using any subnetting of any private address class, provided that the explanation and argument for the solution are stated and explained. 

 

SUBNETTING CALCULATION 

In this section, you are expecting to show the calculation on how to identify the IP address that was assigned for the Online Learning System Server based on the information given in the project scenario. Explain the concept and show the calculation to identify the IP address. 

196.168.0.0/24: Ranges between 196.168.0.0 and 196.168.0.255 with 254 possible hosts. 

The number following the IP address is the abbreviation for the subnet mask, and the number of ones in the subnet mask when expressed in the binary notation is equal to the number of the abbreviation. 

For example, the /8 subnet would have 8 ones in a row, and the rest of the numbers being zeros: 11111111.00000000.00000000.00000000, which equals to 255.0.0.0 when converted from binary into decimal. 

Subnet is a division of large IP Networks into multiple Small Logical Networks. Subnet mask is a 32-bit number used to identify the Network portion and the Host portion in the IP Address. There are 2 types of Subnetting, FLSM (Fixed Length Subnet Mask) and VLSM (Variable Length Subnet Mask). In our project we are using FLSM to calculate the subnetting based on the number of faculties. 

FLSM 

• The Binary to Decimals. 
• Formula 2^n = N. 
• Dividing an IP Network of the same size. 
• The Subnet remains with its boundary class.

                        

                  Each CIDR increment doubles the number of networks 

Private addressing scheme used in Cobham College campus network: 

196.168.0.0 /24 

The number of the faculties: 

4 faculties = subnet 

Step 1 

If I start with a /24, how many sub-networks could I create for 8 IP addresses? 

There are 8 /28 networks inside a /24 

 

/24 --> /25 (x2)

 

/24 --> /26 (x4)

 

/24 --> /27 (x8)

 

/24 --> /28 (x16) 

 

 /28 - /24 = 4 

To calculate the number of possible subnets, use the formula 2^n, where n equals the number of host bits borrowed. If there have 4 host bits borrowed, the n=4. 2^4=16, so sixteen subnets are possible if there have 4 host bits borrowed. 

Step 2 

Possible Number of Hosts per Subnets 

To calculate the number of possible hosts per subnet, use the formula 2^n -2, where h equals the number of host bits. The reason two addresses must be subtracted is because of the network address and the broadcast address. 

Determine the number of remaining host bits based on the class of address and the number of host bits borrowed. 

              Where did 240 come from? 

             225.225.225.240 

                             The last octet for the IP address 

                             Calculation for the last octet in IP address: 128 + 64 + 32 + 16 = 240

STEP 3 

To complete the fourth step of the subnetting process, calculating the decimal and prefix values of the new subnet mask. 

The 4th available address of the Cobham College IT Centre is 196.168.0.72, which is also the IP address of the server. We do not start from 196.168.0.65 since it will be assigned to router IP address as we need to identify the 4th accessible address. So, it will begin at 196.168.0.66 and so on.