📉 VLSM Calculator
⚡ Output
ℹ️ About VLSM Calculator
The VLSM Calculator is a specialized network design tool that implements Variable Length Subnet Masking. VLSM allows network engineers to divide an IP address space into subnets of different sizes, matching the specific host requirements of each segment. This is far more efficient than traditional "classful" subnetting, as it prevents the waste of precious IP addresses.
This tool takes your base network range and a list of your required host counts. It automatically calculates the optimal CIDR prefix for each subnet, ensuring that larger requirements are handled first to maximize the use of available space. It provides a detailed breakdown for each subnet, including the network address, usable IP range, and broadcast address.
📖 How to use VLSM Calculator
- 1. Enter your starting base network in CIDR notation (e.g., <code>172.16.0.0/16</code>).
- 2. List the number of hosts needed for each of your subnets, separated by commas (e.g., <code>100, 50, 25, 2</code>).
- 3. Click 'Run Tool' to generate the allocation plan.
- 4. Review the 'Calculated Subnets' table to find the specific configuration for each network segment.
❓ Frequently Asked Questions
Why are subnets sorted by size?
To maximize address efficiency and prevent fragmentation, VLSM best practices require allocating the largest subnets first.
Does it account for the Network and Broadcast addresses?
Yes. The tool automatically adds 2 to your 'Requested Hosts' to ensure the subnet is large enough to include the mandatory network and broadcast identifiers.
What happens if my requirements exceed the base network?
The tool will process subnets until the space is exhausted, and then provide an error for any remaining requirements that don't fit.
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