Subnet and VLAN Provisioning Planner

Give the planner your site's container prefix, any existing allocations, and the VLANs you need (name plus size). It carves non-overlapping subnets with next-fit allocation, assigns the first usable address as the gateway, and renders IOS XE configuration you can paste straight into the switch: VLAN and name, SVI, DHCP excluded address range, and a DHCP pool with network, default router, DNS, and lease.

When you need it: standing up a new branch site and carving its /21 into per-VLAN subnets, adding a VLAN to a site where earlier allocations already dot the container block, or producing consistent switch config for every new segment without hand-typing SVIs and DHCP pools.

What it does

• Next-fit subnet allocation inside your container prefix
• No overlaps with existing allocations, natural alignment respected
• Size by host count (100) or explicit prefix (/24)
• Gateway at first usable, static range excluded from DHCP
• Rendered IOS XE config: vlan, SVI, ip dhcp pool, exclusions
• Pro: plan a whole site from CSV, export ZIP, saved plans

Frequently asked questions

What does the planner take as input?

A container prefix for the site, any subnets already in use, and the VLANs you need, each with a name and a size.

How are the subnets chosen?

Next-fit allocation inside the container, with no overlaps and natural alignment respected. Size each VLAN by host count or by an explicit prefix length.

What config does it produce?

Ready-to-paste IOS XE: the VLAN and name, the SVI with the first usable address as the gateway, a DHCP excluded range for the static block, and a DHCP pool with network, default router, DNS, and lease.

Open Subnet and VLAN Planner in the app

All tools: CiscoTools.dev · Config Diff · IOS to NX-OS Translator · Config Sanitizer · Template Manager · Config Compliance Checker · BGP Best-Path Explainer · Interface Cleanup Auditor · Network Script Builder · SanitizeDrop (Desktop) · Network Configurator (download) · NetOps Widgets (download) · Pro