Modified on 20 September 2024
Imagine a giant apartment complex with thousands of residents. Delivering mail would be a nightmare for the postal worker! In networking, large, unmanaged networks can be just as chaotic. That’s where subnetting comes in.
What is Subnetting?
Subnetting is the process of dividing a large network into smaller, logical subnetworks. It’s like creating smaller apartment buildings within the complex, making it easier to manage and deliver information (packets) to specific devices.
Why Subnet?
There are several reasons to subnet your network:
- Efficiency: Large networks can become congested with broadcast traffic, slowing everything down. Subnetting reduces broadcast domains, keeping traffic local and improving overall network performance.
- Security: By segmenting your network, you can restrict access to certain devices or groups of devices. This adds an extra layer of security, preventing unauthorized users from accessing sensitive information.
- Scalability: As your network grows, you can easily add new devices to specific subnets without affecting the entire network.
Do You Need to Subnet?
Here are some scenarios where subnetting is beneficial:
- Large network size: If you have a large network with hundreds or even thousands of devices, subnetting becomes increasingly important. A large number of devices on a single network can lead to congestion, broadcast storms, and security vulnerabilities. Subnetting helps to alleviate these problems by dividing the network into smaller, more manageable segments.
- Departmental separation: Do you have different departments within your organization, such as sales, marketing, and finance? Subnetting allows you to create separate subnets for each department. This can improve security by restricting access to sensitive information and resources. For example, the marketing department might not need access to the financial data stored on the finance department’s subnet.
- Security requirements: If you have devices with varying security requirements on your network, subnetting can be a valuable tool. You can create separate subnets for high-security devices (like servers) and low-security devices (like guest printers). This helps to isolate any security breaches and prevent them from spreading to other parts of the network.
- Network growth planning: Even if you have a small network today, subnetting can be a wise decision if you anticipate future growth. By subnetting from the outset, you’ll have a more scalable network foundation that can easily accommodate additional devices as your needs evolve.
In contrast, subnetting might be less necessary for a small home network with just a handful of devices, like a personal computer, laptop, tablet, and smartphone. However, as your home network expands to include smart home devices, gaming consoles, and devices used by guests, subnetting can become a way to organize your network for better performance and security.
Subnetting Step-by-Step (The nitty-gritty)
Subnetting involves working with IP addresses and subnet masks. IP addresses are like street addresses for devices on your network, consisting of four sets of numbers separated by periods (e.g., 192.168.1.1). Subnet masks, also written with four sets of numbers separated by periods, define which part of the IP address identifies the network and which part identifies the specific device (host) within that network.
Here’s a step-by-step guide to subnetting:
- Define your needs: The first step is to assess your network requirements. How many devices do you need to accommodate on your network? How many subnets would be ideal for managing these devices efficiently? You can expect to have a varying number of devices per subnet, depending on your specific needs. For example, you might create a separate subnet for guest users with limited access, while another subnet could house all the servers on your network.
- Choose a network address: This is the main IP address assigned to your larger network. It will be similar to a standard IP address but will likely have a few zeros at the end to represent the subnet portion that will be defined later.
- Select a subnet mask: The subnet mask is a critical element in subnetting. It determines how many IP addresses are available within each subnet. Subnet masks are written in the same format as IP addresses (four sets of numbers separated by periods), but they use ones (1) to indicate the network part of the IP address and zeros (0) to indicate the host part. The more ones in the subnet mask, the larger the network portion and the fewer usable IP addresses within each subnet. There are online subnet calculators available to help you choose the most appropriate subnet mask for your needs based on the number of desired subnets and devices per subnet.
- Calculate subnet addresses and broadcast addresses: Once you have your network address and subnet mask, you can calculate the subnet address and broadcast address for each subnet. The subnet address is the starting IP address for a particular subnet, while the broadcast address is the last usable IP address within that subnet. Devices within the same subnet will share the same network address in the first part of their IP addresses, but they will have different host addresses assigned by the latter part of the IP address.
- Assign IP addresses to devices: Finally, you can assign unique IP addresses to your devices within the usable range of each subnet. Remember to avoid using the subnet address and broadcast address for device assignments, as these addresses have special purposes within the subnet.
Pros and Cons of Subnetting
Pros:
- Improved network performance
- Enhanced security
- Increased scalability
- More manageable network
Cons:
- Requires planning and configuration
- Adds complexity to network management
- May require additional hardware (routers)
Conclusion
Subnetting is a valuable tool for network administrators. By understanding its benefits and following a step-by-step approach, you can create a more efficient, secure, and scalable network for your needs. If you’re unsure whether you need to subnet, consider the size and complexity of your network, and its future growth potential. Remember, a well-planned subnetted network is a happy network!
Also have a look at our guide on DNS for further information on setup of your home/office network
