SUBNETTING CALCULATION

What is a subnet? 

A subnet, or subnetwork, is a network inside a network. Subnets make networks more efficient. Through subnetting, network traffic can travel a shorter distance without passing through unnecessary routers to reach its destination.


CALCULATION

The UTEM network uses private address class C which is 192.168.4.0 /24.

In UTEM, there are 5 faculties and 1 IT Center. Each faculty is given their network address respectively. Also, IT Center in UTEM is assigned as another subnet with its own network address. From this network address, the 4th available address is assigned as the address of the Online Learning System Server

In order to do subnetting, we must primarily know the total number of networks we need to subnet. In this scenario, the UTEM must have 6 subnets to fulfill the 5 faculties and 1 IT Center. To begin the calculation, the minimum number of subnets that satisfies the requirement must be chosen. It is the powers of 2 where it starts with 1, and keeps doubling the values. For an instance, 1, 2, 4, 8, 16, … etc.

In our case, the minimum number of subnets that satisfies the requirement is 8. Thus, we will be using 8 as the number of subnets for the calculation. Although only 6 subnets were needed for UTEM, we choose 8 because it is the nearest number of subnets to 6 and could fulfill the requirement needed.


 2n ≥ N,              where N is the requirement

 8 ≥ 6

 23 ≥ 6       →     condition satisfied ü

               As 8 = 23,                ]

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power of the 2 which is 3 refers to the number of bits that will be borrowed from the host portion of the IP address to the network portion of the IP address.

                                                                                                       :Default


   192.168.4.0/24 

Mask:                                      

255.255.255.224

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Now, the network address 192.168.4.0 is subdivided into 8 subnets. Each subnet has 32 host addresses which includes 1 network address, 1 broadcast address and 30 usable addresses.

Quantity of host per subnet = 2^h-2= 2^5-2=30 hosts


No.

Network ID

Usable host ID range

no. of usable host ID

Broadcast ID

1.

192.168.4.0

192.168.4.1 – 192.168.4.30

30

192.168.4.31

2.

192.168.4.32

192.168.4.33 – 192.168.4.62

30

192.168.4.63

3.

192.168.4.64

192.168.4.65 – 192.168.4.94

30

192.168.4.95

4.

192.168.4.96

192.168.4.97 – 192.168.4.126

30

192.168.4.127

5.

192.168.4.128

192.168.4.129 – 192.168.4.158

30

192.168.4.159

6.

192.168.4.160

192.168.4.161 – 192.168.4.190

30

192.168.4.191

7.

192.168.4.192

192.168.4.193 – 192.168.4.222

30

192.168.4.223

8.

192.168.4.224

192.168.4.225 – 192.168.4.254

30

192.168.4.255


As listed above in the table, these are the addresses which have been subdivided into 8 subnets with network IDs, usable host IDs and broadcast IDs. The IT Center in UTEM is assigned in the 6th subnet which ranges from 192.168.4.160 – 192.168.4.191. In these range of addresses, the first address (192.168.4.160) is used as the network ID and the last address (192.168.4.191) is used as the broadcast ID. There are 30 more usable host IDs within this range. The Online Learning System Server is assigned as the 4th address in the 30 usable host IDs.

Hence, the Online Learning System Server address is 192.168.4.164 /27.

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