If you’re new to VLSM (Variable Length Subnet Masking) or struggling to solve VLSM problems, you’re in the right place. In this article, we’ll break down the process of solving VLSM problems step by step using scratch paper. You don’t need any fancy tools or software, just a pen and paper!
Introduction
VLSM is a technique used to allocate IP addresses more efficiently by subnetting a network into smaller subnetworks. It allows for better utilization of IP address space, saving valuable resources. While it may seem intimidating, with a systematic approach and the right tools, solving VLSM problems becomes much easier.
Breaking Down the Problem
Let’s start by understanding the problem we’re trying to solve. We have a network topology with several networks, each requiring a specific number of IP addresses. Our goal is to find the appropriate subnet size for each network, ensuring efficient IP address allocation.
Assigning Network Sizes
To begin, we need to determine the appropriate size for each network. We’ll use a cheat sheet that provides the number of IP addresses for each subnet size. Based on the requirements for each network, we can identify the right subnet size.
For example, if a network needs 12 IP addresses, we can use a /28 subnet, which provides 14 total IP addresses and 12 usable IP addresses. Similarly, for a network requiring 4 IP addresses, a /29 subnet, offering 6 total IP addresses and 4 usable IP addresses, would suffice.
Continuing this process for each network, we assign the appropriate subnet size based on the number of IP addresses required.
Assigning Network IDs
Once we have determined the subnet sizes, we can assign network IDs to each subnet starting from a predetermined IP address. This starting IP address can be chosen arbitrarily or provided in the problem statement. In our case, we’ll use 9.9.9.0 as the starting address.
Starting from the largest subnet size, we allocate the network IDs by incrementing the appropriate values determined by the subnet size. For example, if the subnet size is /28, the increment would be 16, meaning each subsequent network ID would be 16 more than the previous one.
We repeat this process for each subnet size until we have allocated network IDs for all subnets.
Conclusion
And that’s it! By following the steps outlined above, you can effectively solve VLSM problems using just scratch paper. The key is to break down the problem, determine the appropriate subnet sizes, and systematically assign network IDs. With practice, you’ll become more proficient and be able to solve VLSM problems more quickly.
Remember, VLSM is an essential skill for network engineers and anyone working with IP address allocation. It allows for efficient use of IP address space, ultimately saving resources. So, keep practicing and mastering VLSM to enhance your networking skills.
If you want to dive deeper into VLSM and enhance your understanding of network security, cryptography, or SSL/TLS, check out our course on Practical Networking at PracNet.net.
