VLSM Planner
Plan variable-length subnet allocations from a base CIDR.
VLSM Planner allocates variable-length subnets from a parent CIDR block based on host requirements. Variable Length Subnet Masking allows different subnets inside the same address space to use different prefix lengths, so a network needing 200 hosts can receive a larger block while a point-to-point link receives a much smaller one. Good VLSM design sorts larger requirements first, rounds each host count up to the next valid block size, and leaves room for growth. The result is an address plan that reduces wasted IP space compared with equal-size subnetting. Use this planner for documentation and change review, then validate assignments against existing routes, VLANs, DHCP scopes, cloud networks, and reserved address policies.