Subnet masking in networking: Workings, Types, Importance, Drawbacks and more

The subnet mask, or subnet masking, is the process of differentiating networks into smaller and manageable subnetworks, dividing the large city into smaller districts. This is crucial and delineates the network portion of the IP address from the host portion and enabling the device to reside within a small local network to a different one. To better understand subnet masking or network masks, unlock the ability to design secure, scalable, and high-performance networks to ensure smooth data flow and efficient resource utilization. 

In this blog, explore what a subnet mask is, how it works, its benefits and drawbacks, and much more. 

What is a Subnet Mask?

A subnet mask is a 32-bit address that segregates an IP address into network bits that identify the network and host bits, which identify the host device operating on the network. It encapsulates the range of IP addresses that the subnet uses, wherein the subnet is a smaller network within a more extensive network. Subnetting, or dividing the network into small pieces, is used to make the network easy to maintain.

The subnets and subnetting offer various benefits, processes that require additional hardware such as routers, which potentially cost extra to implement. Subnetting helps to improve the network performance and experience for easy maintenance, advanced network security to not access the other network, minimum network traffic, and much more. 

How does Subnet Mask Work?

Subnetting is the key to creating a fast and efficient computer network. Subnets allow the network traffic to pass through a minimum number of routers, so data packets need to traverse short distances using mini-routes to reach the target audience within the more extensive network.

The process of subnetting includes breaking down the IP address into smaller units, which are assigned to individual network units within the original network. This is done by using various techniques, and subnetting divides the IP address into two parts, which are the network address and the host address. Then, using the subnet mask technique, you can further divide the address into units and assign them to various devices in the network. 

For example, the IP address with a /24 subnet mask can be divided into two sub-networks of /25. 

Importance of Subnet Masking in Networking

Oops! Traffic on your network is increasing rapidly, causing it to run slower. Then, it’s high time to consider subnetting your network. The subnetting needs proper planning and is time-consuming, but trust us, it’s all worth the effort. 

Below are the various benefits of subnet masking in networking to enhance performance and growth. 

Improved Network Performance and Speed

A single broadcast packet is sent for information, which reaches every device connected to the network, as each device has an entry point into the network. The large number of entry points negatively affects the internetwork switching to device performance and improves overall performance. Subnetting ensures information remains in the subnetted network, which allows other subnets to increase speed and efficiency. It also divides the network broadcast domain to better control traffic flow and enhance network performance. 

Boost Network Security

You might be wondering, “What if a device in my network gets compromised?” Splitting the network into subnets allows the control flow of traffic using QoS, ACLs, or route maps, which help to identify threats, close points of entry, and target the response easily. You can also split the network using a router to connect subnets using the configuration of ACLs on the router and switches. As a result, the device uses subnets, which are unable to access the entire network. The other option is to limit access to resources on wireless clients, ensuring the sharing of valuable information to remote locations. 

Reduce Network Congestion

Subnetting ensures that traffic is destined for the device within the subnet and reduces congestion. The strategic placement of subnets helps to reduce the network load and work efficiently on the routing traffic. But what happens to large networks with no subnets? Every system will broadcast packets from all computers and servers in the network and resulting in switches that move all the traffic to the right ports. But using the router to move traffic with subnets will result in no broadcast traffic, and information will not be routed to other subnets. 

Control Network Growth

When you are planning and designing the network, size is the main factor to consider. The key benefit of subnetting is to enable you to control the growth of your network. You can even use the popular host formula to know the size of the network. Take the number of zeros in the mask of the subnet and convert it to binary, and take two to the power of the network minus two, and voila, you will have the number of hosts for the subnet mask. In the next step, figure out the growth of the network, and in most cases, it will be based on the physical size of your building. 

Ease Administration

Are you the network admin? Subnetting has no barrier, as it makes your job a lot easier. Subnetting creates networks that have logical host limits as opposed to the limitation of IP addressing classes: Eight bits for Class A, 16 bits for Class B, and 24 bits for Class C. If the Internet were limited to three classes, every network would have only 16 million IP addresses for host devices. In the absence of subnets, a network with more than 254 devices needs a Class B allocation, which wastes thousands of IP addresses.

Drawbacks of Subnet Masking

Using subnetting to design the network channel does not always prove to be efficient, but in some cases, it affects the overall communication channel of the network, so it’s important to remember some points when applying subnetting to the network. 

Complex Connection

Subnetting introduces complexity in network design and management, which requires careful planning and configuration to ensure smooth and proper subnet functionality. It also involves managing multiple levels of addressing, such as subnets, networks, hosts, etc., which can be highly challenging for some users to understand. Each subnet requires its own routing table entry, at least on the local router, which increases the size and complexity of routing tables. 

Increased Cost

Subnetting uses the necessary additional hardware, such as switches, routers, and other network devices, which can increase the network infrastructure cost. Managing the multiple subnets needs extra administrative overhead, which includes managing IP addresses, routing, and security policies. The need for additional network equipment adds to the overall infrastructure expenses and increases the hardware cost, especially in a network with various subnets. 

Unused IP Address

Each subnet needs a network address and broadcasts the address, which cannot be assigned to individual hosts. This results in certain degrees of IP address waste, which is particularly true in small subnets. The inefficient subnetting can exacerbate the issue, which leads to a shortage of usable IP addresses. Each subnet needs dedicated IP addresses for subnet ID, which leads to IP address wastage if not planned correctly.

Potential for Misconfiguration

The wrong or incorrect subnet mask calculation or overlapping subnet range causes network connectivity problems. The misconfiguration led to routing errors, communication failure, and IP address conflicts. Troubleshooting these issues is time-consuming and challenging, and the wrong subnet mask results in a device being assigned to the wrong network, which leads to communication failure. Overlapping the subnet range occurs when two or more subnets are assigned to the same IP address space. 

What is the Subnet Mask Calculator?

The subnet mask calculator is a tool or software that automates the process of subnetting. It helps the network administrator determine the network information with the network address as the base address of the subnet. The broadcast address sends data to all devices within the subnet and the usable host range of IP addresses that are assigned to the devices. 

The usable host number functions as a key element for determining subnet masks while determining the maximum device count on the subnet. The subnet mask definition includes both CIDR notation and decimal format together with network and host portion definitions. The process of subnet calculation involves understanding binary format and determining the required number of subnets and hosts while knowing the subnet mask followed by performing computations for network and broadcast addresses and usable host range and numbers.

Types of Subnet Masks and Their Applications

The subnet masks play an important role in networking and host portions of IP addresses, which enable efficient network segmentation. 

The following are the various types of subnet masks and their applications. 

Default Subnet Masks

The default subnet masks are automatically related to the IP address classes. The Class A (255.0.0.0 or /8) is used for very large networks with a wide number of hosts and provides a large host range, but a limited number of networks are used in large enterprises, national networks, and companies that need extensive host allocation. The Class B (255.255.0.0 or /16) is suitable for medium-sized networks and offers a balance between a number of hosts and networks. 

Variable Length Subnet Masking (VLSM)

Variable-length subnet masking allows for the use of different subnet masks within the same network. It also enables efficient address space allocation by creating subnets of different sizes. These network masks optimize the IP address allocation in the complex networks and create subnets with specific host requirements. 

Custom Subnet Masks

The custom subnet masks are used to create subnets that match the specific network requirements. This also offers flexibility in network design and optimizes the host allocation. These network subnets divide the network into small and more manageable subnets and allow the creation of subnets with specific host requirements. It optimizes the IP addresses’ utilization and implements the network security policies. 

Classless Inter-Domain Routing (CIDR)

Classless inter-domain routing uses slash notation to showcase the subnet masks like /24, /16, etc. It eliminates the traditional IP address classes, allows flexible address allocation, and enables supernetting, which combines multiple networks into large networks. These subnets are used for multiple applications for internet routing and address allocation, and route aggregation to reduce the routing table size. 

Emerging Technologies in Subnet Masking

The subnet masking principles may remain consistent, but the emerging technologies are influencing how subnetting is managed and implemented. 

Explore some of the emerging technologies in subnet masking for better network performance.

Cloud computing

The subnet mask uses cloud platforms that rely on subnetting to isolate the virtual network and resources. The virtual private cloud (VPC) uses subnetting to create isolated virtual network environments for cloud tenants. The cloud provider offers various tools and services to automate subnet creation and management. The cloud-based subnetting allows for easy scaling of networks and integration with other cloud services. 

Network Automation

The network automation tools and scripts help to streamline the subnet creation, IP address allocation, and network configuration. This technology helps to reduce the risk of human error and enhance network security and efficiency. Infrastructure as Code (IaC) tools allow the management of network infrastructure, which includes subnets, using code. 

IPv6 Subnetting

The IPv6 subnetting is the whole transition, as it drives changes in the subnet practices. IPv6 uses long addresses and different subnetting schemes like prefix length and offers great flexibility, and it also addresses the space compared to IPv4. There is stateless address autoconfiguration (SLAAC), which simplifies the IPv6 address assignments. Also, this technology offers various security features for a safe network. 

Software-Defined Networking (SDN)

The SDN helps to separate the network control plane from the data plane, which enables centralized network management. The SDN controllers use the automated subnet creation, IP address allocation, and network segmentation. This simplifies the subnet management and allows for dynamic network configuration, and allows for more granular control of network traffic based on the subnets. SDN allows demand subnetting, which changes the network configuration in real time. 

Network Virtualization

The network virtualization technology, like virtual routing, virtual LANs, etc., works in conjunction with subnetting. VLANs segment the physical network into multiple logical networks, which enhances security and network performance. This also enables the creation of virtual subnets and networks, which provide great scalability and flexibility. The network virtualization allows for the creation of an overlay network, which can span across multiple physical networks. 

Conclusion

Subnet masking is a crucial concept of networking, which is the backbone of efficient IP addressing management and network organization. It divides the large networks into small, manageable subnets to achieve optimized resource allocation, enhance security, and improve overall network performance. From basic binary operations to complex network subnet masks, it empowers the network administration to design a robust, secure, and scalable network infrastructure.