VXLAN VNI Calculator
Work out how much of the 16.7 million VNI space a multi-tenant VXLAN design consumes.
Inputs
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
Values used
Tenants = 250 tenants; L2 segments per tenant = 12 segments; L3 VNIs per tenant (VRFs) = 1 VNIs; VNIs reserved for infrastructure = 4,096 VNIs
VXLAN VNI
VXLAN carries a 24-bit VNI, so the space is 2^24 = 16 777 216; VNIs required = tenants × (L2 segments + L3 VNIs).
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
How it works
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
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.