IPv6 planner for sites and VLANs
IPv6 tool to expand/compress addresses, plan prefixes per site/VLAN, visualize space, compare scenarios, and export tables.
Plan IPv6 for sites and VLANs without overlaps
IPv6 planner: convert, plan, and compare
Convert IPv6 addresses, calculate prefixes per site/VLAN, and export a neutral plan with space visualization. Designed for desktop and mobile.
Advanced
Bits per hextet
The prefix is highlighted with a border.
Enter a valid IPv6 to see the results.
Network (CIDR)
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Expanded
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Compressed
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/64 prefix
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Interface ID
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1) Mode
Select “Convert” to expand and compress IPv6 with strict validation.
2) Input
Enter the address with or without a prefix; the system shows warnings if it is not valid.
3) Results
Copy the network (CIDR), expanded or compressed with one tap.
Complete the base prefix and sites to generate the plan.
Space visualization
Site zoom
Tap a site to see the zoom or the VLAN list.
Table by site
| Site | Assigned prefix | /64 capacity | Used | Free | Range | Waste | |
|---|---|---|---|---|---|---|---|
| Add sites and generate the plan to see results. | |||||||
VLAN detail
The copy block uses a neutral format: SITE;VLAN;PREFIX;GATEWAY_SUGGESTED;NOTES.
1) Mode
Use “Plan” to assign prefixes per site and VLANs.
2) Inputs
Enter the base prefix and define VLANs or lists per site.
3) Results
Review the table, cards, and space visualization.
4) Export
Export CSV or copy the neutral plan for documentation.
5) Steps
Check the step-by-step mode at the end to understand each calculation.
Scenario A
Copy plan A
Scenario B
Copy plan B
Shared sites
The comparison uses the same sites/VLANs for both scenarios.
Comparison A vs B
Scenario A
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/64 capacity: 0
Waste: 0
Free: 0
Scenario B
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/64 capacity: 0
Waste: 0
Free: 0
How the IPv6 plan is built
Base prefix normalization
We convert the IPv6 to 128 bits, apply the mask, and validate that the prefix is aligned. If it is not, we offer to correct it to the network prefix.
From VLANs to /64
Each VLAN consumes a /64. Reservations add extra capacity within the site block.
Minimum prefix per site (powers of 2)
We calculate the next power of 2 to cover VLANs + reservations and obtain the minimum prefix: /64 - k.
Nibble alignment (optional)
When enabled, we round the prefix to the next wider multiple of 4 (for example /58 → /56) and record the extra waste.
Sequential allocation and gaps
We assign blocks per site in order, respecting prefix alignment. The free gaps are stored for visualization and summary.
Visual example of bits
/48 → /56 → /64 means the change happens in hextets 4 and 5:
2001:0db8:1234:0000:0000:0000:0000:0000 (/48)
2001:0db8:1234:ab00:0000:0000:0000:0000 (/56)
2001:0db8:1234:ab12:0000:0000:0000:0000 (/64)
Frequently asked questions about the IPv6 planner
Why is /64 per VLAN recommended?
IPv6 defines /64 as the standard size for LAN subnets because it enables SLAAC and simplifies design. The planner assumes /64 by default for each VLAN.
What is the difference between ULA and GUA?
ULAs (fc00::/7) are unique local addresses intended for internal networks. GUAs (2000::/3) are global and routable on the Internet.
How does :: compression work?
:: compression replaces the longest sequence of zero hextets. It can appear only once and the leftmost sequence is chosen in case of a tie.
What is nibble alignment?
It is a strategy that rounds the prefix to multiples of 4 bits (/48, /52, /56, /60, /64) to make reading and documentation easier.
How is the block per site calculated?
VLANs and reservations are added and the next power of 2 is computed. That value yields the site's minimum prefix.
What happens if a site does not fit?
The planner indicates which site does not fit and suggests expanding the base prefix or reducing reservations/alignment.
What is link-local?
Link-local addresses (fe80::/10) only work on the local link and are not routed between networks.
