VXLAN VNI Calculator
Work out how much of the 16.7 million VNI space a multi-tenant VXLAN design consumes.
About VXLAN VNI Calculator
VXLAN replaces the 4094 usable VLAN IDs with a 24-bit identifier, giving 16.7 million segments. Each tenant consumes one VNI per L2 segment plus one per routed VRF, and infrastructure VNIs are normally carved out of a reserved block. The VNI space is effectively unlimited, but the practical limits — VNIs per switch ASIC and per EVPN control plane — are much lower, so the real value is knowing the design's shape before you hit a platform ceiling.
Formula
VXLAN VNI
VXLAN carries a 24-bit VNI, so the space is 2^24 = 16 777 216; VNIs required = tenants × (L2 segments + L3 VNIs).
- VNI
- 24-bit VXLAN Network Identifier that replaces the 12-bit VLAN ID
- L3 VNI
- Transit VNI used per VRF for symmetric IRB routing
Worked example
With the default values below, VXLAN VNI Calculator returns VNIs Required of 3,250. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Tenantsaccepts 1–200,000 tenants
- 250 tenants
- L2 segments per tenantaccepts 1–4,096 segments
- 12 segments
- L3 VNIs per tenant (VRFs)accepts 0–64 VNIs
- 1 VNIs
- VNIs reserved for infrastructureaccepts 0–1,000,000 VNIs
- 4,096 VNIs
Results
- VNIs Required
- 3,250
- Total VNI Space
- 16,777,216
- Usable VNIs
- 16,773,120
- VNI Space Consumed
- 0.0194%
- VNIs Remaining
- 16,769,870
- Tenants This Space Supports
- 1,290,240
Step by step
- 1Values used
- 2VXLAN VNI
- 3VNIs Required= 3,250
- 4Total VNI Space= 16,777,216
- 5Usable VNIs= 16,773,120
- 6VNI Space Consumed= 0.0194
- 7VNIs Remaining= 16,769,870
- 8Tenants This Space Supports= 1,290,240
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is VXLAN VNI calculated?
VXLAN carries a 24-bit VNI, so the space is 2^24 = 16 777 216; VNIs required = tenants × (L2 segments + L3 VNIs). VXLAN replaces the 4094 usable VLAN IDs with a 24-bit identifier, giving 16.7 million segments. Each tenant consumes one VNI per L2 segment plus one per routed VRF, and infrastructure VNIs are normally carved out of a reserved block.
Why does VXLAN VNI matter?
The VNI space is effectively unlimited, but the practical limits — VNIs per switch ASIC and per EVPN control plane — are much lower, so the real value is knowing the design's shape before you hit a platform ceiling.
What values do I need to enter?
This calculator takes 4 inputs: Tenants, L2 segments per tenant, L3 VNIs per tenant (VRFs), VNIs reserved for infrastructure. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.