Updated May 31, 2023
Introduction to Subnetting and Supernetting
The process of dividing a network into subnetwork is called as subnetting, and the process of combining small networks into a large network is called supernetting. In subnetting, the numbers of bits of network addresses are increased, and in supernetting the number of bits of host addresses is increased. Supernetting is designed to make the routing process more convenient. It reduces the size of routing table information; therefore, it consumes less space in the router’s memory. FLSM and VLSM methods are used for subnetting, and for supernetting, CIDR is used.
What is Subnetting?
- Subnetting is a technique that is used to divide the individual physical network into a smaller size called sub-networks. These sub-networks are called a subnet. An internal address is made up of a combination of the small networks segment and host segment. A subnetwork is designed by accepting the bits from the IP address host portion; then, they are uses to assign a number of small-sized sub-networks in the original network.
- In the subnetting process, network bits are converted into host bits. Subnetting process is performed to slow down the depletion of the IP addresses. It allows the administrator to divide the single class A, class B and class C into small segments. Subnetting makes use of VLSM (Variable Length Subnet Mask) and FLSM (Fixed Length Subnet Mask). The process of partitioning the IP address space into a subnet of different size is called a Variable Length Subnet Mask. VLSM reduces the wastage of memory. The process of partitioning the IP address space into a subnet of the same size is called a Fixed Length Subnet Mask.
Advantages and Disadvantages of Subnetting:
Below are some advantages and disadvantage of subnetting:
- Subnetting increases the number of allowed hosts in the local area network.
- Subnetting decreases the volume of broadcast, hence minimize the number of network traffic.
- Sub networks are easy to maintain and manage.
- Subnetting increases the flexibility of address.
- Network security can be readily employed between sub networks rather than employing it in the whole network.
- The process of subnetting is quite expensive.
- To perform subnetting process, we need a trained administrator.
What is Supernetting?
Supernetting is the process that is used to combine several sub networks into a single network. Its process is inverse of the subnetting process. In supernetting, mask bits are moved towards the left of the default mask; network bits are converted into hosts bits. Supernetting is also called router summarization and aggregation. It creates a more number of host addresses at the expense of network addresses. The Internet service provider performs the supernetting process to achieve the most efficient IP address allocation.
It uses the CIDR method, i.e. Classless inter-domain routing method, to route the network traffic across the internet. CIDR combines several sub networks and combined them together for routing network traffic. In other words, we can say that CIDR organizes the IP Addresses in the sub networks independent of the value of the Addresses.
Advantages and Disadvantages of Supernetting:
Below are some advantages and disadvantage of supernetting:
- Supernetting reduces the traffic of the network over the internet.
- Supernetting increases the speed of routing table lookup.
- As it is summarized the number of routing information entries into a single entry, the size of the router’s memory table decreased, hence saving the memory space.
- Provision for the router to isolate the topology changes from the other routers.
- The combination of blocks should be made in power 2 alternatively; if the three blocks are required, then there must be assigned four blocks.
- While merging several entries into one, it lacks covering different areas.
- The whole network must exist in the same class.
Difference Between Subnetting and Supernetting
- Subnetting divides the whole network into sub networks while supernetting combines the sub network and merge it as a whole network.
- Subnetting converts the bits of a host to bits of network hence increase the number of network bits, while supernetting converts the bits of a network to bits of the host, hence increase the number of host bits.
- Subnetting reduces the depletion of address, while supernetting increases the routing process.
- Subnetting uses VLSM and FL techniques, while supernetting uses CIDR.
- In subnetting, mask bits are moved towards the right of the default mask, whereas in supernetting, the mask bits are moved towards the left of the default mask.
Here in this article, we have seen the process of subnetting and supernetting. We have also seen its advantages and disadvantages. Both are inverse of each other. Subnetting and supernetting, both techniques are used to increase IP address availability and decrease the depletion of IP address. We have also seen the difference between these two techniques.
This is a guide to Subnetting and Supernetting. Here we discuss what is subnetting and supernetting with advantages & disadvantages, and difference. You may also have a look at the following articles to learn more –