VLSM Subnet Planner
Allocate subnets of different sizes from a parent network block. The planner sorts them largest-first and allocates address space with zero waste.
Configuration
| Subnet Name | Required Hosts | |
|---|---|---|
Address Space Overview
Allocated Subnets
| Name | Network | Prefix | Subnet Mask | Wildcard | First Host | Last Host | Broadcast | Usable |
|---|
What is VLSM?
VLSM allows network engineers to divide an IP block into subnets of different sizes. Unlike classful subnetting, VLSM lets you allocate a /26 for 50 hosts, a /28 for 10 hosts, and a /30 for a WAN link — all from the same parent block.
VLSM formula
To find the prefix for N hosts: find the smallest n where 2^n − 2 ≥ N. The prefix is /(32−n).