Difference Between Subnetting and Supernetting

Subnetting is the technique of partitioning a large network into smaller networks. On the other hand, the supernetting is the method used for combining the smaller ranges of addresses into larger space. Supernetting was devised to make the routing process more convenient. Additionally, it reduces the size of routing table information so that it could consume less space in the router’s memory. The well-defined method for the subnetting is FLSM and VLSM while for supernetting CIDR is used.

Subnetting and supernetting are the techniques invented for resolving the problem of address depletion. Although, the techniques were not able to eliminate the problem, but certainly decreased the rate of address depletion. Supernetting is inverse process of subnetting.

Content: Subnetting Vs Supernetting

1. 1. Comparison Chart
   2. Definition
   3. Key Differences
   4. Advantages
   5. Disadvantages
   6. Conclusion

Comparison Chart

Basis for comparison	Subnetting	Supernetting
Basic	A process of dividing a network into subnetworks.	A process of combining small networks into a larger network.
Procedure	The number of bits of network addresses is increased.	The number of bits of host addresses is increased.
Mask bits are moved towards	Right of the default mask.	Left of the default mask.
Implementation	VLSM (Variable-length subnet masking).	CIDR (Classless interdomain routing).
Purpose	Used to reduce the address depletion.	To simplify and fasten the routing process.

Definition of Subnetting

Subnetting is a technique of partitioning an individual physical network into several small-sized logical sub-networks. These subnetworks are known as subnets. An IP address is made up of the combination of the network segment and a host segment. A subnet is constructed by accepting the bits from the IP address host portion which are then used to assign a number of small-sized sub-networks in the original network.

The Subnetting basically convert the host bits into the network bits. As mentioned above the subnetting strategy was initially devised for slowing down the depletion of the IP addresses.

The subnetting permits the administrator to partition a single class A, class B, class C network into smaller parts. VLSM (Variable Length Subnet Mask) is a technique which partitions IP address space into subnets of different sizes and prevent memory wastage. Furthermore, when the number of hosts is same in subnets, that is known as FLSM (Fixed Length Subnet Mask).

Definition of Supernetting

Supernetting is inverse process of subnetting, in which several networks are merged into a single network. While performing supernetting, the mask bits are moved toward the left of the default mask. The supernetting is also known as router summarization and aggregation. It results in the creation of more host addresses at the expense of network addresses, where basically the network bits are converted into host bits.

The supernetting is performed by internet service provider rather than the normal users, to achieve the most efficient IP address allocation. CIDR (Classless Inter-Domain Routing) is scheme used to route the network traffic across the internet. CIDR is a supernetting technique where the several subnets are combined together for the network routing. In simpler words, CIDR allows the IP addresses to be organized in the subnetworks independent of the value of the addresses. 

Advantages of Subnetting

• Minimizes the network traffic through decreasing the volume of broadcasts.
• Increases addressing flexibility.
• Increases the number of allowed hosts in local area network.
• The network security can be readily employed between subnets rather than employing it in the whole network.
• Subnets are easy to maintain and manage.

Advantages of Supernetting

• The size of the router memory table is minimized by summarizing several routing information entries into a single entry.
• It also increases the speed of routing table lookup.
• Provision for the router to isolate the topology changes from the other routers.
• It also reduces the network traffic.

Disadvantages of Subnetting

• However, it is quite expensive.
• It requires trained administrator to perform subnetting.

Disadvantages of Supernetting

• The combination of blocks should be made in power 2; alternatively, if the three blocks are required, then there must be assigned four blocks.
• The whole network should exist in the same class.
• When merged, it lacks covering different areas.

Conclusion

Subnetting and supernetting both the terms have inverse meaning where subnetting is used to separate the smaller subnetworks form each other by dividing a larger network. Conversely, supernetting is used to combine the smaller range of addresses into a larger one to make routing process more easy and fast. Ultimately, both techniques are used to increase the availability of the IP addresses and reduce the depletion of IP addresses.